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Linux Essentials for Ethical Hackers - Full InfoSec Course — Transcript

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0:00this linux course will teach you the
0:02basics you need to know as a penetration
0:04tester it was created by hackersploit
0:07who has one of the most popular cyber
0:09security channels on youtube hey guys
0:11hackersploit here back again with
0:13another video and welcome to the linux
0:15essentials for hackers the 20 you need
0:18to know and uh first of all let me
0:20explain to you what this series is about
0:22before we actually take a look at what
0:24we'll be covering and the various issues
0:27that uh you know uh
0:28beginners in infosec
0:30and ethical hacking usually face when
0:33dealing with the topic of linux so uh it
0:36comes as no surprise that linux is very
0:38very important uh to learn if you are
0:40going to get into infosec because uh you
0:42will be
0:43using various linux based uh offensive
0:47distributions like kali linux or parrot
0:49os and it's it's imperative that you
0:51understand how to use the system to your
0:53advantage how to become efficient at it
0:56and that's primarily what this course is
0:58focused on now if you are a system
1:00administrator then it is uh worth also
1:03going through this course because we'll
1:05be covering a various aspects that you
1:07might not have known about but again if
1:10you're a beginner this is perfect for
1:11you this will cover exactly what you
1:13need to know to be efficient and
1:16effective with linux uh when it comes
1:18down to pen testing or ethical hacking
1:21getting started is very simple if you
1:22are a pen tester or you're a beginner to
1:25linux uh you can install linux from
1:27scratch or run it in a virtual machine i
1:30prefer running you know installing it
1:32from scratch on a physical machine
1:34however if you are interested in you
1:36know delving into the various
1:38distributions that exist you can check
1:40out distrowatch.com and you can start
1:42playing around with them uh you know in
1:44a vm
1:45or you could opt to set up a linux
1:47server all right so that's pretty much
1:49all that i wanted to talk about in
1:51regards to an introduction to this
1:53course and without further ado let's get
1:55cracking
2:00in this video we're going to get started
2:02with taking a look at the various
2:03keyboard shortcuts that will help you
2:06navigate around the system much easier
2:08and work with the terminal at a much
2:10more efficient rate all right so let's
2:12get started now i'm currently using
2:14ubuntu you can be using any other linux
2:17distribution that you want
2:19and we're going to be primarily working
2:21with the terminal first before we
2:23actually delve into desktop environments
2:26uh and you know various other
2:28distributions so we're going to be using
2:30debian and again ubuntu is based off
2:32debian and for our package manager we'll
2:35be taking a look at the aptitude package
2:37manager but as i said we'll be delving
2:39into all of that later on all right so
2:41with ubuntu uh getting opening up a
2:44terminal with your keyboard is very
2:46simple you have your control alt n t key
2:49or you have your super and t if you're
2:51running debian or any other distribution
2:53so on ubuntu it's ctrl alt n t
2:56or your super nt and you can customize
2:58your keyboard shortcuts uh however you
3:01want all right so
3:02let me just uh let me just minimize this
3:04now uh the other interesting thing that
3:07you can do or very helpful thing that
3:09you can do when working with various
3:11windows it doesn't have to be a
3:13a terminal window is you can perform
3:16tiling and that is by using the super
3:17key and your arrow keys to direct the
3:20location of the windows and you can tile
3:22them appropriately right so as you can
3:25see i've used the super and up key and
3:27that maximizes it and of course i can
3:29take it to the left or i can take it to
3:31the right and i can you know leave it
3:33where where it was previously right so
3:35let me just expand it now let me talk
3:37about a font size right so font size is
3:40very easy to change and to actually
3:42increase and reduce so if i wanted to
3:44increase my font size i would use the
3:46control shift and the plus key on my
3:49keyboard and that would increase the
3:50font size right
3:52i can then minimize it by using the
3:54control and the minus key on my keyboard
3:56and that will reduce the font size so
3:58again increasing it is ctrl shift and
4:01and the plus key
4:03and reducing the font size is control
4:05and the minus key on your keyboard right
4:08so
4:09that is how to increase and reduce your
4:12font size now let's talk about
4:14actually clearing your screen which is
4:16very very simple so i'll just use a
4:18generic command here you don't have to
4:20worry about what that command is so if i
4:22wanted to clear my terminal i would
4:24simply say clear and that will get rid
4:26of all the content that was currently on
4:28the terminal however
4:30i can also use a keyboard
4:33keyboard shortcut so again if i just
4:36list the same command here i can use the
4:38control and l key and that will clear
4:40the terminal for me without me having to
4:42type the clear command all right so
4:44let's talk about some uh some other
4:46keyboard shortcuts that you should be
4:48aware of right so uh if we are working
4:51with a particular process so for example
4:54i can say
4:55nmap i can run a quick nmap scan here
4:58and i can just say sv
5:00192.168.1.1
5:02and we can hit enter i can use the
5:04control c key
5:06to actually end the currently running
5:09process and it will return you back to
5:11your uh to your shell uh in this case
5:14we're using the bash shell so if i want
5:16to end a process that's currently
5:18running like the one i was running which
5:20was nmap i use the control and c
5:22keyboard shortcut right now if i wanted
5:25to suspend or to pause this
5:27or to pause a particular task or a
5:30process i can use the control and z key
5:33right so if i was running nmap s v the
5:36same key or the same command i can type
5:39that out however here are other useful
5:41keyboard shortcuts that you can use so i
5:44can cycle through my previously used
5:46commands by using the up arrow key and
5:49that will again cycle through all my all
5:51my previously used commands so again i
5:53can just go to this previous command and
5:55hit enter and then i can use ctrl and z
5:58to actually uh pause and suspend that
6:00process uh in memory and remember it
6:03hasn't stopped it you have just
6:04suspended it all right now let's talk
6:06about tab uh
6:08let's talk about the tab key and auto
6:10completion right so uh we can use the
6:13tab key uh to auto complete file and
6:16directory names so let me just clear
6:18this out and i can use the control and l
6:20key so if i go to my uh well i can
6:22actually work from my home directory but
6:25let's say i wanted to cat a particular
6:28file so let me just list all the files
6:30in here so let's say i wanted to cat my
6:33let's see or let's say i wanted to get
6:35my my password file so again i can say
6:38cat
6:39etsy
6:40and i can say password right now
6:43if i wanted to auto complete this i
6:45could use the tab key and again it'll if
6:48i use it two times it will give me the
6:50various suggestions here so a single tab
6:52will auto complete it if it has an
6:55accurate uh id of of the particular file
6:58or directory you're referring to so
7:00again if i said uh if i give it a bit
7:02more information in regards to the file
7:04or directory i was looking for i would
7:07simply just hit tab and it gives me the
7:09file there however i can hit double tab
7:12and that again gives me the files that
7:14are related to the particular data that
7:17have entered here so again if i reduced
7:18it just to ap and i hit tab twice it
7:21will give us the recommendations as to
7:24uh in in reference to the to to the
7:27to the particular files that uh that
7:29begin with the word p and again if i can
7:31increase that uh probability or the
7:34specification of the file i'm looking
7:36i'm looking for by increasing the amount
7:38of letters so again
7:40again i can tap it twice and now you can
7:41see the results are more fine-tuned so
7:43again i can
7:45i can use tab to auto complete it to
7:47password and i can hit enter and that
7:49displays the contents of the password
7:50file so that is how to use uh the tab
7:53key and those are the various uh you
7:55know commands that uh or keyboard
7:57shortcuts that you can use while working
7:59in the terminal and hopefully those will
8:00make your life a whole lot easier so
8:02again control and l that clears
8:04everything for me
8:06now let's talk about how to close your
8:08terminal so again closing your terminal
8:10is very simple you can use the control
8:13shift and w key so again i can say
8:15control shift and w here
8:18right over here and that works pretty
8:20universally among all distributions so
8:22again control alt d that opens up your
8:25terminal uh increasing the font size
8:27control shift and the plus key and so on
8:30and so forth and you can tile your
8:32terminal or any window in your system by
8:34using the super key and your arrow keys
8:37or your directional keys here
8:39all right so those are all uh the basic
8:43keyboard shortcuts that i wanted to
8:44start off with i'll be referencing
8:46others throughout the series uh let me
8:48know which ones are i missed and i'll be
8:50seeing you in the next video in this
8:52series
8:56in this video we're going to be taking a
8:58look at file management and file
9:00manipulation uh in linux so let's get
9:03started so i'm just going to open up my
9:05terminal here and let's just expand this
9:08and let's increase the font size so we
9:10can see what's going on all right so
9:12let's start off with a bit of directory
9:15navigation and understanding uh what
9:18files exist within a directory right so
9:21the first question any beginner to linux
9:24has is when the in the terminal is how
9:26do i know where i am or how do i know
9:29what directory i'm in right so they want
9:31to know where where they actually exist
9:34in the linux file system so by default
9:37if you are logged in as a user uh you
9:39know that a user is not the root user uh
9:42so you know a normal user account for
9:44example i'm logged in as a lexis
9:47so i'm going to be in my current home
9:50directory now you can confirm this by
9:53typing in pwd all right pwd means print
9:57current working directory or print
9:59working directory and that is
10:01self-explanatory it prints the current
10:03directory that you are in and that you
10:06uh will be working in or any commands
10:08that you actually run will be executed
10:10within this directory right so i'm going
10:12to hit enter
10:14and as you can see it tells you i'm in
10:16the home alexis directory now user
10:18accounts are usually sorted out this way
10:21so the root account usually has its own
10:24folder in the root directory
10:26of the file system of the linux file
10:29system whereas other users like alexis
10:32here
10:33will be found within the home directory
10:35and then furthermore their own
10:36individual directories based on their
10:38usernames and this is where all their
10:40files will be stored all right which
10:42brings us to the next question which is
10:44how do i list the files within a
10:46particular directory and this is very
10:48simple we use the ls command which means
10:50list all right so i'm going to hit enter
10:53and this will list the files and the
10:56directories within the current directory
10:58right so i'm going to enter and as you
11:00can see it tells us within this current
11:02directory we we have the desktop
11:04directory uh the documents directory
11:07downloads etc etc right so
11:10this is the simple way of listing files
11:12now the ls command has the ability to be
11:15run with other arguments or commands or
11:18options that allow you to increase or to
11:21modify the way the output is
11:24or the way the files are displayed to
11:26you right so a quick example of this is
11:29by using the ls hyphen or dash l command
11:33all right so this will list all the
11:35files and directories in this directory
11:39uh in the format of a list or a table
11:42which makes it easier to read for users
11:45right so i'm going to hit enter and
11:46immediately you can see it gives you a
11:49vital information like the total
11:51right of here the permissions the owner
11:54the ownership of these files and
11:56directories
11:57you have the date modified and the name
11:59of the file uh of the files and
12:01directories
12:02all right so
12:04that is how to use ls in combination
12:06with another command now you can also
12:08get more output by combining the ls
12:11command with other options so again if
12:13we wanted to list all the files that are
12:15all the files and directories that are
12:17currently in this working directory i
12:19can use the a command which essentially
12:22is an abbreviation for all now when i
12:24say all in the context of a linux it
12:26means all hidden files all files within
12:29this directory will be displayed all
12:31right so if i list the files again here
12:33you can see that it only displays the
12:36the files and directories that are
12:38visible to users if we want to display
12:41all the files and directories including
12:43hidden files and directories we can say
12:44ls and we can say a
12:47all right and this again will give us
12:49all files and directories including
12:51hidden files and directory so you can
12:52see the hidden files in linux have the
12:55dot or the full stop
12:57before the file name here so again the
12:59bash aliases file is a file that is used
13:02in configuration of your bash profile so
13:05again it allows you to configure aliases
13:07when working with bash again so the
13:09hidden files in nx typically are used
13:12for configuration of various system uh
13:15system environment variables or various
13:18system tools uh you know so on and so
13:20forth we'll be working with this later
13:22on and it will all make sense shortly
13:25now the great thing about the list
13:26command is that i can use it in
13:28combination with the previous command so
13:30if i wanted to list this in a way that
13:32was much easier to read i can say ls a l
13:36and this will list all the files and
13:37directories including the hidden files
13:39and directories in the format of a list
13:42or a table and i hit enter and there you
13:44are you can see
13:46it displays all the files and
13:47directories in the form of a list here
13:49and again it gives you information in
13:51regards to the ownership and the
13:52permissions more of which we'll touch
13:54upon later on in the course all right so
13:57i'm just going to clear the terminal
13:58here and let's take a look at the ls
14:00command a little bit more all right so
14:02let's say i wanted to um to actually
14:05list the files um in a more
14:08readable format for users so again i can
14:11just type in ls
14:13l and i can use the h command all right
14:15so if i hit enter again this displays it
14:18in a much easier way for uh for users to
14:21understand what's going on and the
14:22context i'm referring to is more to do
14:26with the size all right so if i say ls l
14:28you can see that the data here or the
14:31size of the files is in bytes right now
14:34when we use the ls h or the h where the
14:37h stands for human readable format you
14:39can see it displays the actual size in
14:41kilobytes a much easier way for you to
14:44understand the sizes of files
14:46etc etc all right so let me just clear
14:49the terminal here
14:51and
14:52let's take a look at one more uh command
14:55that we can use with ls and that is if
14:58we wanted to uh show uh subdirectories
15:01right so remember when we show when we
15:03use the ls command
15:05it shows us the directories within this
15:07current working directory but let's say
15:09we had other directories within um let's
15:12see
15:13within pictures right so we could have
15:15other directories within pictures or
15:17documents or the downloads folder etc so
15:20again we can say
15:22uh if i wanted to list
15:24the the the subdirectories within the
15:26desktop folder i can say
15:29ls
15:30l and we'll use the capital r command
15:33and this again means recursively so we
15:36can then specify the folder we want
15:38which is going to be desktop or the
15:40directory we want again it's going to be
15:41desktop and we hit enter and again it
15:44will list for us the files that exist on
15:47the desktop first of all and again it
15:49shows us that we have
15:51a directory called c
15:53and a txt file called todo.txt
15:57all right within the c folder or the c
15:59directory we have three files we have a
16:02temp dot c
16:03we have a test binary and a test.c file
16:06so again it's displayed to us what is on
16:09the desktop and then what is uh what is
16:12in the directory c on the desktop so
16:14again it's used for recursive a listing
16:16of the of files and directories and sub
16:19directories that way all right so i hope
16:22that makes sense now let's talk about uh
16:24some directory navigation all right
16:27which is quite important here
16:29uh before we actually talk about uh file
16:31manipulation um and copying files etc so
16:36as i said we are currently in the home
16:38alexis directory now if i wanted to move
16:41a step back or to move to a parent
16:43directory i can say cp all right so cd
16:47will change directory to the actual home
16:49directory uh so again if i type in pwd
16:52you can see it will not do anything now
16:54if i wanted to go a step back i can type
16:57in cd
16:58and i can follow that or yes i can
17:01follow that up with two full stops and
17:03that will take me a step back and
17:06immediately on your bash shell you'll be
17:08given the current directory that you're
17:10in now so again it's telling us we are
17:12in the home directory and we can confirm
17:14this by typing in pwd right so if we
17:17list the files within the home directory
17:19you can see that the only directory that
17:21exists is the alexis folder and that's
17:23because that's the only use on the
17:25system so let's take a step back right
17:27so i can take a step back and i hit
17:30enter and now we are currently in the
17:32root directory the root file system
17:34directory for the off for linux right so
17:37again i can list all the files in here
17:39and i can hit enter and as you can see
17:41we are now in the root this is the
17:44actual root directory of the linux file
17:46system not the root folder or the root
17:48user directory just the root
17:51of the file system so
17:53you can now see all the various folders
17:55that the linux file system is comprised
17:57of all right so that is how to actually
18:00navigate a step back now if i wanted to
18:02navigate into any one of these
18:04directories i could say cd and then i
18:07specify cd is an abbreviation for change
18:11directory and i can specify the
18:12directory i want to move into so i can
18:15say cd home
18:16right and again that will take me into
18:18my home directory and then i can list
18:20the files in here and this tells me oh
18:22we have a directory called alexisd
18:24and then i can say change directory into
18:27the directory alexis and that will take
18:28me into the uh the directory alexis
18:32all right now i can also use um i can
18:36also use the forward slash to refer to a
18:39directory that is currently not in this
18:41particular directory so let's say i
18:44wanted to move into the um let's see
18:47i wanted to move into the
18:50um let's try the etsy folder i can say
18:54cd
18:56forward slash etsy and this refers to a
18:59directory that is currently not in this
19:01directory but at the root at the root of
19:04the linux file system so i hit enter and
19:07that takes us into the etsy folder so
19:09again i can confirm this by typing in
19:11pwd and again it tells me i'm currently
19:13in the etsy folder
19:15right now if i want to navigate back to
19:18my user home directory so i'm currently
19:21logged in as the user alexis if i want
19:24to go back to alexis home directory i
19:26can simply do this by typing
19:29home alexis right that's very very
19:31simple but if i want to even make this
19:33shorter i can use
19:35the command right over here and again i
19:38can hit enter
19:40and
19:41i can
19:42easily just navigate back to my home
19:43directory so if i hit enter you see and
19:46i type in pwd it's going to take me into
19:48my home directory right over here all
19:51right now that we have taken a look at
19:52you know directory navigation and moving
19:55around directories let's take a look at
19:57uh creating files copying etc all right
20:00so i'm currently on my in my home
20:02directory so let's talk about
20:05actually copying a file
20:07now before we actually do that we need
20:09to actually understand how to create
20:11files really really quickly right so
20:13the first thing i want to do is i'll go
20:16into my desktop here and i'll say cd
20:18desktop and i'm going to hit enter and
20:20i'm in my desktop now all right so if i
20:23wanted to create a file really easily i
20:26can use touch all right so touch is a
20:29is a tool or a utility that allows you
20:31to you know easily create files again
20:33let me show you a command that will help
20:35you understand what various commands and
20:37tools are so if i want to know uh
20:40i want information about a particular
20:42command i can use the what is
20:44the what is command so i can type in
20:46what is and then i can say what is touch
20:49and i can hit enter and again it tells
20:52me change the file timestamps all right
20:54or so i can also say what is
20:56uh let's see what is nano right nano is
20:59a text editor so i can hit enter and
21:02it's going to tell nano is another
21:03editor etc so it gives you information
21:05about a particular command or tool all
21:07right so i can use touch to create a
21:09file remember without any content right
21:11so i can say touch
21:13and i can say the file name is going to
21:15be test.txt
21:17all right i can hit enter and if i list
21:20all the files in the desktop you can see
21:22i have the test.txt file right over here
21:25all right so
21:27i can now
21:28direct data into this file so again i
21:30can use the ech command and if we want
21:33to learn more about the echo command i
21:34can type in what is and i can say echo
21:37and i can hit enter and it's going to
21:39say display a line of text right so we
21:41can say echo
21:43alexis is
21:46alexis is
21:47you can say alexis is not cool i know
21:51something like that
21:52and i can just hit enter and again it
21:54will display on our terminal alexis is
21:56not cool all right so it simply just
21:58displays a line of text however we can
22:00redirect this data into a particular
22:03file and in this case we want to dis we
22:06want to redirect this data into the
22:08test.txt file right so i can say echo
22:12we can say hello
22:14and we'll just use this simple string of
22:16text here and i can say
22:20redirect to this and we use the greater
22:22than sign to redirect data to a
22:25particular file or to a particular
22:27command so i can say test dot txt all
22:30right and i hit enter and now this file
22:34should have the words or the string
22:36hello now if you want to easily just
22:39display the context uh or the content of
22:41a file i can use the cat command all
22:43right now again we can use the what is
22:45command to find uh to find out more
22:48about what the
22:49cat command does so i can hit enter and
22:51it's going to tell us it concatenates
22:53files and prints on the standard output
22:55so again it gives us the output of all
22:57the content it prints out the content of
22:59a particular file uh so again i can say
23:01cat test dot txt and hit enter and again
23:05it prints out what we had redirected
23:07into it
23:09all right so that is how to use the cat
23:11command now again i can redirect a lot
23:13of text into this uh so let's say i
23:15wanted to edit this uh this file or i
23:18wanted to remove this file which is a
23:20much better way of actually taking a
23:21look at you know file manipulation
23:24technique so again i've shown you how to
23:25create a file a very simple file
23:27redirecting output
23:28we can also
23:30use cat to redirect output so for
23:32example if i wanted to redirect the
23:34contents of the password file i can say
23:37cat hc password and i'm using the
23:39relative directory you can see here so
23:41the the the contents of the password
23:44file i want to redirect into the
23:47test.txt file however if i wanted to
23:50create another file i could easily do it
23:52directly from here i could say password
23:54dot txt and i hit enter and now we can
23:57display the contents of the password.txt
24:00file and again i can use the tab
24:02autocompletion here and i hit enter and
24:04again it gives us all the content was
24:06redirected into this new txt file
24:09excellent so now let's talk about
24:11actually you know create removing files
24:14copying them etc so if i wanted to
24:16remove this file here the test.txt file
24:20i use the rm command which stands for
24:22remove right again you can use the what
24:24is command and again use it again it
24:26tells you this is used to remove files
24:28and directories so let's talk about
24:30removing files first
24:33all right so we can say remove uh test
24:35dot txt all right and again we use tab
24:39auto completion and i hit enter and this
24:41will have removed the file over here
24:44right so um
24:46that is essentially how to remove a file
24:48now
24:50uh if i want to remove a directory uh i
24:53can now i need to specify that it is a
24:56recursive action but before we do that
24:58let's talk about creating a directory
25:00first because that that's quite
25:02important as well so if i want to create
25:04a directory i use the make directory
25:06command which is abbreviated into mkdir
25:09so make a directory and i give it a name
25:12so i can say test all right so this is
25:13going to create a folder or id or a
25:16directory called test
25:18right once i hit enter and i list all
25:20the files here you can see we have the
25:21test directory over here uh so what i
25:24can do is
25:26i can you know i can navigate into it i
25:28can copy files into it so let's say i
25:31wanted to copy a file into this uh
25:33directory so again i can say
25:36let's say i wanted to say touch um or we
25:39can do the same thing so i can say cat
25:41etsy
25:43password and i want to redirect this
25:45into a file called
25:47password.txt and once that is done i
25:50want to copy the file so i want to say
25:52cp that means copy and i want to specify
25:54the file that i want to copy which is
25:56going to be password dot txt and i want
25:59to copy that into the test directory so
26:01i specify the directory i want to copy
26:03in i want to copy it into
26:05in this case the test directory is
26:07within the current working directory so
26:09i don't have to specify a relative path
26:11if i was specifying a relative path i
26:13would use the forward slash here so i
26:15can just say test
26:17and i hit enter and now if i remember if
26:20i wanted to list the contents of the sub
26:22directories recursively i could say ls
26:25lr and i hit enter and you can see the
26:27contents of the test directory uh
26:30password.txt
26:32excellent so again if i want to remove
26:34the the password file i can say
26:36removepassword.txt
26:38if i want to remove a directory and the
26:40directory what we want to remove is the
26:42test directory i can say remove and i
26:44use the capital r which means
26:47recursively remove and i say test and i
26:50use the tab autocompletion and i hit
26:52enter and now if we list the files in
26:54the on the desktop you can see we've
26:56gotten rid of all of these folders and
26:59files
27:00all right so
27:01now that we know how to actually create
27:04a directory we can actually um
27:07let me talk about removing a directory i
27:09actually covered it with the remove
27:11command however we can also use um
27:14another command called remove directory
27:16which is abbreviated into rmdir
27:20this will only allow you to remove a
27:22directory if you do not have any files
27:24within that directory right so let's say
27:26i uh
27:28by the way you can cycle through your
27:30previously used commands using your
27:31arrow keys in this case you can use the
27:34uh the up arrow key so let's say i
27:36wanted to catch i wanted to you know
27:38redirect output of the password file
27:40into a file called password.txt and i
27:42wanted to copy this file or let's
27:45actually talk about
27:46moving files so if i wanted to move a
27:48file i would say mv and again you can
27:51use the what is command so what is mv
27:54so i can say mv i want to move the
27:57password txt file into the test
28:00directory here i'm going to hit enter
28:02and now you can see that the
28:04the password file has been moved into
28:06the test directory so again i can
28:09i can list all the files within the test
28:11directory here and that again it tells
28:13me that we only have the password.txt
28:15file in here so if i use the rm dir
28:19command which means remove directory and
28:21i say test remove directory test you can
28:24see it's going to tell me that this
28:26directory is not empty so as a result we
28:28need to specify remove
28:30recursively
28:32test and we're going to hit enter and
28:33now it gets rid of the test directory
28:36for us all right so those are uh very
28:39very simple ways of
28:41you know creating copying and of of
28:43course deleting commands now uh
28:45before we actually end this video which
28:47i know has been going on for quite a
28:49while i'm going to be covering file
28:50directory permissions later but i want
28:53to talk
28:53i want to talk about file manipulation a
28:56little bit more uh so we've talked about
28:58uh you know using the cat command
29:00redirecting output uh using touch as
29:02well moving files let's talk about you
29:05know renaming files
29:07uh and also taking a look at the content
29:09of particular files here so what i want
29:12to do now is
29:13let's actually take a look at um
29:16at actually renaming files all right so
29:18i'm going to again use the similar
29:20command that we had used i'm just going
29:21to you know
29:23i'm going to redirect the output of the
29:25password file into a file called
29:26password.txt
29:28and now if i wanted to rename the
29:30filepassword.txt
29:32into something else i would use the mv
29:34command right so there isn't a command
29:36to rename files in linux you use the mv
29:40command which means move
29:42in this case it's very simple the syntax
29:44is uh you specify the file that you want
29:47to change the name of which is going to
29:48be password.txt and i changed the file
29:51name to let's say
29:53test
29:54dot txt
29:56and hit enter and now if we list all the
29:58files in the directory you can see that
29:59it changes it to test.txt and indeed if
30:03we actually uh if we actually
30:06display the contents of the file you can
30:08see that the the content is preserved
30:10while we've changed the name and we can
30:12also change the extension of the file so
30:15i could say move
30:16test.txt into test
30:19let's say test.c we can we can change
30:22the contents into a c file right and now
30:24if i say uh cat test dot c
30:27i can hit enter and there you are now
30:29let's talk about uh editors and then
30:31i'll talk about the content of the files
30:33uh before we actually end this video so
30:37um
30:38there are two uh standard editors that
30:40are pretty much the standard when it
30:42comes to linux and working within the
30:44terminal i'm not talking about graphical
30:46uh gui based editors like uh g edit and
30:50stuff so if i wanted to edit this file
30:52within the terminal i have two options i
30:54have nano so again i can use the what is
30:57command and say what is nano and again
30:59that's an editor and i have we have vim
31:02which is pretty much the most popular
31:04option and i'll be making independent
31:06videos on this editors and how to
31:07configure them so again if i want to
31:10edit the test.txt file i can say nano
31:13test.tx
31:15test.c
31:16let's actually rename it back to
31:18test.txt
31:20dot txt and we say nano test
31:23dot txt and we're hit enter and that
31:26takes us into nano now exiting nano is
31:28very simple again you can navigate
31:30around make changes uh exiting it we use
31:32control and x and that's it now with v
31:35vim or vi we simply type in vi or vim
31:38and we say test.txt hit enter and again
31:42with them the syntax is very different
31:43if i want to make changes or i want to
31:45add content i type in i to insert text
31:48and again i can play around with it and
31:50once i'm done i hit escape and then i
31:52can write changes to this file or i can
31:54quit and discard any changes by typing
31:56in q
31:57and the exclamation mark and hit enter
32:00and that's how to use the various
32:01editors i'm not covering them uh you
32:03know to their full to their fullest
32:05extent and that's because we have
32:06various videos that will be actually
32:09focused on editors themselves so um
32:12that's pretty much all that i wanted to
32:13cover in this video there's quite a bit
32:15hopefully you guys can actually learn a
32:17lot from this video
32:22in this video we're going to be talking
32:23about file and directory permissions and
32:26ownership all right so again there's
32:28quite a bit to cover and hopefully i'll
32:30explain the various ways of doing it and
32:32i hopefully i can explain it as best as
32:34i can all right so let me just open up a
32:37terminal here and we can get started
32:38immediately right so
32:40let's just expand this and there we are
32:42all right so the first thing i'm going
32:44to do is i'm just going to go on to my
32:45desktop or change my directory onto my
32:48desktop and i'm just going to clear this
32:50now one thing i want to talk about
32:51before i actually get started if i list
32:53all the files in here you can see that
32:55directories will typically be
32:57highlighted in blue and to keep this on
33:00a standardized basis you want the color
33:02scheme for your terminal to be the linux
33:05console or you can use xterm if you want
33:07and again that will just keep it really
33:09standardized but for the purpose of this
33:11video i'm just going to stick to the
33:13linux console again just so directories
33:16and
33:17your directories are highlighted blue
33:19and again executable files are
33:21highlighted green all right so that'll
33:23keep things uh more simple and very easy
33:25to understand all right so let's get
33:27started so again if i list all the files
33:30in this directory uh you can see that um
33:34typically when i list it in the form of
33:36a list or a table we have various bits
33:38of information right so again i can also
33:41you know
33:42type this in and print it out print it
33:44out in human readable format but again
33:47that doesn't explain
33:49a lot of the information that already is
33:51here all right so we have the first
33:53column which is your file permissions
33:55file and directory permissions um you
33:58then have the user and the group all
34:01right so this is to do with ownership
34:03these two are to do with ownership you
34:05then have the file size uh and the date
34:07modified and of course you have the the
34:10file or the directory name
34:12as is
34:13as as is and as was created all right so
34:17what i'm going to do is the first thing
34:18i want to do is i'm just going to create
34:20a simple file i'm just going to call it
34:21test
34:23test dot sh because i know many of you
34:25don't like me sticking with one type of
34:27file
34:28and what i'm going to do is i'm just
34:29going to cut the contents of the
34:31password file
34:32into the test dot sh file right
34:36and i can just hit enter and we can
34:37clear this out and let me also create a
34:39directory here and we'll just call it
34:41test and let's clear this out all right
34:43so now if i list all the files here
34:45you can see that
34:47we have the new files that we just
34:49created test.sh and the test directory
34:52so
34:53if we take a look at the permissions for
34:55the sh file which is a shell file and is
34:58potentially executable however in this
35:00current state it isn't and you might be
35:02asking well why isn't it executable and
35:05that's where file and directory
35:07permissions come into play now
35:10permissions in linux are very very
35:11simple to understand now many people
35:14usually you know complicate it quite a
35:16bit and there isn't a need for this uh
35:19again there are two ways of handling it
35:21which is where most of the confusion
35:23starts that is the symbolic mode format
35:26and the uh the octal mode or the binary
35:29mode as it's so referred to as all right
35:32and these basically deal with various
35:34techniques as to which you can ascertain
35:36or set
35:37uh you know their various permissions
35:40for files and directories but the first
35:41thing you need to understand first of
35:43all if you're a beginner is there three
35:45types of permissions that you can apply
35:47to a file or directory in linux those
35:50are read which is represented by r as
35:53you can see right over here uh the the
35:55second one is the w or the right
35:58permissions and the last one is the x
36:01permission which stands for executable
36:03so these basically mean read this allows
36:06this means that you're allowed to read
36:08the file uh the right permission means
36:11you're allowed to write changes to the
36:13file and the x permission means you're
36:15allowed to execute the file now you
36:17might be saying well we have various uh
36:20various
36:21sequences of these permissions appearing
36:24here how is it sorted out and that's a
36:26very good question so let's take a
36:28simple example of the test.sh file right
36:31over here all right so first of all uh
36:34as you'll see right over here each of
36:36these is sorted into
36:38six uh into six columns however they're
36:41really not separated but that's how you
36:43have to understand them so you have your
36:44first one here you have your second one
36:47here and you have your third one here
36:49now this initial prefix here is
36:52is there to tell you the type of file
36:55you're dealing with in this case we're
36:56dealing with a file so it leaves that
36:58blank in the case of if of a directory
37:01it will be annotated by a d and that
37:04tells you that you're dealing with a
37:06directory all right so let's let's talk
37:08about the other columns here so the
37:10first uh the first one here is for the
37:13owner of the file alright so these are
37:16the owner permissions now when we're
37:18talking about ownership for this
37:19particular file we can see that the
37:21owner of the file and the group that it
37:23belongs to
37:25is alexis all right now if it belonged
37:27to another user that means that these
37:29permissions were specific to that
37:31particular user or the owner of the file
37:34the second column here is in uh these
37:37are the permissions for the group all
37:39right so again these are group
37:40permissions and the last one are for all
37:43other users on the system so let's say i
37:46created a file and i'm currently in the
37:48alexis uh the home alexis desktop
37:51directory here
37:52uh let's say i was logged in as another
37:55user and i navigated into this directory
37:59and i tried to execute this file over
38:01here well given that i would be i was
38:04using another user
38:06the permissions for this file
38:08explicitly state that i can read the
38:11file however i cannot execute it or i
38:14cannot write any particular changes to
38:16it so hopefully that makes sense now
38:19let's talk about changing these
38:20permissions or setting these permissions
38:22for these files now this is where the
38:24chmod command comes into place all right
38:28so the chmod commands allows you to
38:30change the mode for files and
38:32directories and allows you to change
38:34permissions for the file and directories
38:36so again i can say i can use the what is
38:38command with chmod and you can see it
38:41allows you to change the file mode bits
38:43and change the permissions of a file or
38:45directory right quite simple
38:48now let's talk about this for a second
38:49it's very easy to use we say chmod
38:52and then we specify the options that we
38:55want and finally after the options we
38:57specify the file to which we want to
39:00apply these permissions to all right so
39:02very very simple syntax however as i
39:04mentioned there are two ways of doing
39:05this many people are comfortable with
39:07their own way and i recommend that you
39:09find your own way of going about this
39:11but i will make a recommendation to make
39:14things a whole lot easier and maybe uh
39:16one way that you can understand it you
39:18know a whole lot better all right so
39:20that the the first way is by using the
39:23symbolic mode format all right and the
39:25second way is by using the octal
39:28or the binary mode all right so let's
39:31start off with the symbolic mode format
39:34all right so let's say i wanted to
39:36change the permissions
39:38for the file
39:39the file test dot sh right over here all
39:42right so you can see that we we
39:45currently cannot execute it so uh what
39:47i'm going to do is let me just remove or
39:50i can just
39:51what i can do is just
39:53get etsy or we can just say dev null and
39:56don't worry what i'm doing here i just
39:58want to
40:01dot sh and we can actually just say echo
40:05um we can say
40:07echo hello world and we can just use
40:10this and we can pipe that into the file
40:13test.sh and now if we try and execute
40:16this file
40:17you can see that we hit enter we can see
40:20that we do not have the particular or
40:22the necessary permissions to execute
40:24this so that will be our goal here our
40:26goal is to set uh or to provide uh the
40:29user lexis with executable permissions
40:32all right so let me just list this one
40:34more time and we can take a look at the
40:35permission so for the owner alexis he
40:38can only read and write changes to the
40:41file which we we pretty much did already
40:43uh for the group they can only read the
40:45file uh and for all other users they can
40:49only read it all right so let's talk
40:50about the symbolic mode format
40:52so the symbolic mode format is very
40:55simple to understand of course i've
40:56mentioned it has to do with the various
40:58permissions so read write and execute
41:01and it is done in conjunction with the
41:03chmod command all right so now with the
41:06chmod command i can now specify
41:10the specification in regards to the
41:12uh to the user the group uh
41:16the uh the other or for all users all
41:18right so what this means is
41:20if i wanted to specify permissions or
41:23set permissions for uh for the current
41:25user i would do that by typing in chmod
41:28u
41:29and then i can add permissions i can say
41:32you um i can say i can add permissions
41:36by using the plus sign or i can say u is
41:39equal to and then i would set the
41:41permission so i can say user
41:44the current user is going to be
41:46read write and execute
41:48we're going to provide this user with
41:50the read write and execute permissions
41:52and then we specify the file that we
41:54want to apply these permissions to so i
41:56can say test dot sh all right and i can
41:59hit enter now if i list all the files
42:01here again you can now see that the the
42:04user alexis or the owner alexis has read
42:08write an executable permissions which
42:09means we can now execute this file and
42:12we just entered a simple piece of uh
42:14code here so again we can say test.sh
42:17and again we we cannot we can actually
42:19just modify this sorry uh we can say
42:21just going to test.sh and we can just
42:23say
42:24echo
42:25so that whenever we print it out we can
42:27actually get those
42:29this little string of text here again so
42:31let me just write and exit there and you
42:34can see that that was successful so
42:36again if we execute the file here you
42:38can see it prints out the string hello
42:40world excellent so now we have set the
42:42permissions for the user using the
42:44symbolic mode format all right so we can
42:47also remove permissions
42:49uh and again i've shown you how to
42:51explicitly set the permission so again
42:53let's go over that one more second one
42:55more time so chmod and now let's say we
42:58wanted to apply uh these same
43:00permissions for all the users on the
43:03system all right and for for for for the
43:06group all right so to do this we use the
43:09group
43:10uh and the o sign uh or we can also use
43:13the a sign all right
43:15and that will mean a group and all other
43:18users on the system so group and all of
43:20these users on the system so again the
43:23standard definition is
43:25for use the current user or the owner of
43:27the file g is for the group uh and again
43:30o is for other and a is for all all
43:33right so that will set for all so we can
43:35say group and we can then say group and
43:37other
43:38uh is will have read write and
43:41executable permissions and then we
43:43specify the file here and we hit enter
43:46and then that will set the permissions
43:47explicitly so again if we list all the
43:49files now you can see that the the the
43:52current user uh the group and all other
43:55users have read write and executable
43:57permissions which means i can now
43:59execute this file if i was logged in as
44:01another user that belongs to any other
44:04group on the system which is not
44:06recommended so let's talk about how to
44:08remove these permissions all right so i
44:10can say chmod
44:13and let's say i wanted to remove the uh
44:16the right and executable permissions for
44:19for the groups and other users on the
44:21system so again we say go and now we say
44:25minus
44:26wx so the right and executable
44:29permissions and we say test dot sh and
44:31we hit enter and now if we list all the
44:34files here you can see that now we have
44:36removed all these permissions so the
44:39only the current user is only allowed to
44:41read write and execute the file however
44:43the group and the other users on the
44:45system are only able to read it so that
44:48is essentially how to use the symbolic
44:50mode format so you can see it's a very
44:52simple system to use let me just go over
44:54it one more time we use the chmod
44:57command we then specify the user uh the
44:59group
45:00uh other
45:02uh other or all all right so again ugo a
45:05that is the standard uh
45:08the standard definition there and then
45:10of course we use the plus or the equal
45:12signs to add permissions or to
45:14explicitly set them so for example if i
45:18wanted to give the group execute
45:20executable permissions i would say chmod
45:24group plus x all right so we're setting
45:27it for the group and we're giving it
45:29executable permissions we then specify
45:31the file
45:32and we hit enter and now if we list all
45:34the files here you can see that it gives
45:36the group executable permissions so it
45:39can read the file and execute it however
45:41it cannot it cannot write changes to the
45:43file so i can i can also get rid of it
45:46so again chmod minus we can say group
45:49minus x
45:50uh so remove the executable permissions
45:52and then we specify the file we hit
45:55enter and again if we list the files
45:57here you can see we're back to the old
45:59uh permission so again a very simple way
46:02of setting permissions
46:04all right now let's talk about uh the
46:06binary or the octal mode of setting
46:09permissions
46:10all right so now let's talk about the
46:12octal or the binary mode of setting
46:15permissions right which is again very
46:17simple and is my preferred way of
46:19actually going about doing it now again
46:21as i said it's entirely up to you all
46:23right so again we are still using the
46:25chmod operator here and again this is
46:29the standard so again we can say chmod
46:31and then now when dealing with the
46:34binary or the octal mode of setting
46:36permissions
46:37the read write and executable
46:40permissions are now denoted in a binary
46:43format and you might be saying well if
46:45that's the case doesn't that make it a
46:47little bit complex well i'll explain why
46:50it it will not make it complex all right
46:52so let me explain something so typically
46:55as i said the read uh right and
46:57executable permissions are now
46:58represented by a binary value all right
47:02so the read value is
47:04the the read permission is represented
47:06by a value of four all right the right
47:09permission
47:11is execute is uh is denoted or
47:13represented by a value of two sorry and
47:17the executable permission is represented
47:20by a value of one all right and again
47:23we're still following the previous uh
47:26the previous format of going of actually
47:28uh understanding permissions here so
47:31again we have the uh the owner now the
47:33owner of the file or the directory uh
47:36you then have the group and others uh
47:39other users on the system
47:41all right so let's work with the test.sh
47:44file and i'll talk about setting
47:45directory permissions which is again
47:47very very simple as well
47:49all right so
47:51let's say we wanted to get rid of the
47:55the write and execute permissions for
47:57the owner of the file which is right
48:00over here you can see it has read write
48:02and execute permissions so to do this
48:04with the the binary mode or the octal
48:08mode
48:09again we need to specify chmod and now
48:12the permissions if you already know
48:14about this are now represented by the by
48:17binary values all right so as i said for
48:21the owner
48:22we want to actually specify the
48:25following so again we can say
48:28chmod
48:29and for the owner we need to specify the
48:33we want to get rid of the right and
48:35executable permissions so we only have
48:38the
48:38the write permission which again as we
48:41said is going to have a value
48:43of four all right so we start off with
48:46the value of four so we're going to say
48:47chmod four
48:49and then for the other files uh uh also
48:51for the other for the group and for the
48:54other uh users on the system we want to
48:56use the same permission we so we're
48:59gonna say chmod four 444
49:02and then we specify the file name
49:05test.sh and we hit enter and now if we
49:08list the files in here you can see that
49:10now the file
49:11only has read permissions
49:14for the owner the group and other users
49:16on the system all right so that's how to
49:18set it now if i wanted to give the um
49:21the owner of the file read write and
49:23execute permissions we would need to add
49:26these binary values together all right
49:28so read is going to be equal to four all
49:31right right is going to be equal to two
49:34and um
49:35and execute is going to be equal to one
49:38all right so two plus four
49:40is going to be six six plus one is going
49:42to be 7. so we say chmod 7 that is for
49:46the user permissions or the owner
49:48permission so read write and execute
49:50let's say for the group and the other
49:54users on the system we want to give them
49:56only read permissions which again is
49:58denoted by four so that's four uh read
50:02permissions for the group
50:03and for other users on the system the
50:05same thing and then we type in the name
50:08of the file all right and i'm gonna hit
50:10enter
50:11and we can now display this and
50:13immediately you can see we now have read
50:15write and executable permissions for the
50:17owner for for the group we only have
50:19read permissions and for other users on
50:22the system we only have read permissions
50:24all right so that's very easy to
50:25understand now if it is complex i will
50:28leave a uh a resource in the description
50:30section that has a table of all of these
50:33permissions but the math is very simple
50:35right so again we're simply adding 4
50:37plus
50:38plus 2 plus 1 and that is for all
50:41permissions so this is
50:43right
50:44so again this is
50:46sorry this is read write
50:48and this is execute so 4 plus 2 plus 1
50:50is going to be 7. if i only want read
50:53permissions it's going to be four if i
50:55only want
50:57read and write permissions it's going to
50:58be six again that would be uh seven six
51:02six or if i only wanted um
51:06read
51:06uh and execute permissions that would be
51:09uh so for example if we wanted for the
51:11user or the owner read write and execute
51:14permissions that would be seven and then
51:16for the group and for all of the users
51:18we only wanted read and execute
51:20permissions that would be seven five
51:21five all right so it's very easy to set
51:24permissions this way and again you're
51:26always setting explicitly for the user
51:29uh for for the owner the the the user
51:32the group and then all the other users
51:34on the system so that's something you
51:36need to take
51:37into consideration all right so now
51:39let's move on to actually uh changing
51:42you know directory permissions all right
51:44so if i list all the files here again
51:46you can use the symbolic mode or the uh
51:48the octal mode whatever is comfortable
51:50with you we have the test directory that
51:52we created so again if we wanted to
51:54provide it with all permissions you can
51:56see that it has read write permissions
51:59for the current user and for the group
52:02and the other users it only has read
52:03permission so again we can say chmod
52:06uh user we if we use the symbolic mode
52:09we can say user
52:11uh user group and other that's going to
52:13be equal to read write and execute and
52:16then we say test the name of the
52:18directory and we hit enter and now if we
52:20list all the files in here you can see
52:22that the permissions have been set
52:24uh and then again if we wanted to go
52:26back i can say chmod
52:29and let's say we only wanted the file to
52:32be re we only wanted the user to be able
52:35to read and
52:37write to this particular directory then
52:39we would say this is going to be equal
52:41to 4 plus 2 is going to be 6
52:444 4 and then we say test and we hit
52:46enter we again we can just confirm the
52:49permissions have been changed and there
52:50you are so that's how to set uh
52:52permissions on a directory however if
52:55there are other directories and files
52:57within this directory then we need to
53:00set these permissions we can set them
53:02recursively and to do this we can then
53:05type in chmod
53:07and if we use the r command the capital
53:09r command that means recursive
53:11permissions so again we can then say uh
53:14before we do that let's actually move
53:16this file the test file the test.sh file
53:20into the test directory
53:22and you can see it it tells us that we
53:25do not have adequate permissions and
53:27that's because again if we list all the
53:30if we list all the permissions here for
53:32the the directory
53:35uh if we say for example uh for this
53:37particular file
53:39let's say we want to say chmod 755 test
53:43dot sh and now we say move uh test dot
53:46sh into the test directory and we hit
53:49enter that is telling us that we cannot
53:51move it nuts primarily because of the
53:54the the permissions for the directory so
53:56we can say chmod 755 a test and we hit
53:59enter and then we can say move
54:02we can then say test.sh into the test
54:05folder here and we hit enter and now we
54:07can move it all right so that proves
54:09again that the importance of permissions
54:12and understanding them so now if we
54:14check the directory test uh the the
54:17files within the directory test we have
54:19the test.sh file so now if we wanted to
54:22to actually provide this directory and
54:25all the files within it files and
54:27directories within it recursively with
54:29all permissions i could say chmod
54:33777 and that gives it read write and
54:35executable permissions for the the owner
54:38uh the group and all other users on the
54:40system so again i would say chmod
54:43recursively 777 and i'm using the octal
54:46mode as you would have guessed and then
54:48we specify the directory and hit enter
54:50and now if we list all uh the directory
54:52itself you can see it has all
54:54permissions if we list uh all the files
54:57uh within the the test directory if we
55:00list the permissions here you can see
55:02that the test.sh file now has all has
55:04also uh those permissions and they have
55:07been applied recursively so if i had any
55:10other files or directories within this
55:11directory uh they would have been
55:13applied as well all right so now that we
55:15have actually uh taken a look at file
55:17ownership uh sorry file permissions
55:20let's take a look at file ownership
55:25in this video we're going to be talking
55:27about file ownership which is a fairly
55:29simple topic to understand and again in
55:32the previous video we used the chmod
55:35operator
55:36or the chmod tool and in this video
55:38we're going to be using the ch own tool
55:41again which is quite self-explanatory it
55:44allows us to change the ownership of
55:46files and directories which is quite
55:48important all right so as we did in the
55:50previous video
55:52you can see that we were able to
55:54change the permissions for this for the
55:57test directory and the test files within
56:00it and i've just changed them back to
56:02some pretty standard uh uh to some
56:04pretty standard permissions here and
56:06again uh we also had the
56:10we also had the uh the test.sh file
56:13within the test directory so
56:15let's talk about ownership so as i
56:17mentioned the current owner of this file
56:20right over here is alexis and this is
56:22the this is denoted uh right over here
56:24so the ownership information and the
56:26group ownership information if there is
56:29any
56:30now as i said uh we we haven't talked
56:32about adding users and groups which is
56:34fairly simple we haven't talked about
56:36you know setting particular permissions
56:37for users uh you know uh within the uh
56:40the sudo as file but that's something
56:42we'll get to later
56:43so if we wanted to change the ownership
56:45of this file
56:47to
56:48uh
56:49to to let's say the root user i can do
56:51that very very easily so again i can say
56:54let me just go into the the root user
56:56here and now i'm currently logged in as
56:59the root user so if i wanted to change
57:00the ownership and i'll go into the test
57:03directory if i wanted to change the
57:05ownership of the test.sh file
57:08what i can do now is i can say ch own
57:11and again you can use the what is tool
57:13or the what is utility to actually give
57:15you some more information about the the
57:18ch own tool so again it tells you this
57:20allows you to change your file owner and
57:23group and of course change the ownership
57:25of a file
57:26all right so now if i wanted to change
57:28the ownership of the test.sh file
57:31from alexis to to the root user i can do
57:34this very very easily so i can say
57:37i can say ch own
57:38and then i specify the the the user i
57:41want to uh to actually change the
57:44ownership to in this case to the root
57:46user and then i'll specify the file name
57:48which is going to be test.sh and i hit
57:50enter and now if i list all the files
57:53here you can see that the owner of the
57:55file has been changed to root however
57:57the group of this file is still alexis
58:00all right so that's something that we
58:01also have to change to change the group
58:04or to change the group order here
58:06it's very simple we use the change group
58:08command which again is denoted by
58:11uh it is denoted by change grp so chgrp
58:15and again we can use the what is tool
58:16change drp hit enter and this allows you
58:19to change group ownership so let's say
58:21we want to change the group ownership to
58:23root as well or to the root group
58:26if we type in groups and we say root
58:29again that tells us what
58:31what group the root user belongs to and
58:34as you can see it belongs to the root uh
58:36due to the root group uh and again we
58:39can say groups alexis and uh you can see
58:42these are the groups that the user lexis
58:43belongs to it belongs to the to the
58:46group alexis adm cd rom sudo etc etc
58:50all right so let's say i wanted to
58:52change the group of this file so change
58:54group
58:55um
58:56and then i say change it to the group
58:59root
59:00and i want you to change the file
59:01test.sh and now if we list the
59:03permissions here or the ownership sorry
59:05um
59:07we can see now that the owner of the
59:09file is the root user
59:11and the the group ownership of this file
59:13belongs to the to to to the group uh two
59:16to the root group right over here all
59:19right so that is how to use the ch own
59:22and the ch
59:23group or the change group command to
59:25change the ownership of a file now again
59:27we haven't experimented with users yet
59:29and that's something we'll be touching
59:30upon quite soon so we'll be explaining
59:34this as we move along
59:39in this video we're going to be talking
59:40about how to use the grep tool in
59:42regards to looking for data or
59:44information in files all right so this
59:46is one of the most important linux
59:48utilities or tools that uh you can you
59:51can learn how to use and it will really
59:52improve your efficiency when dealing
59:54with data and working in the terminal
59:57okay so let's actually get started with
59:59understanding what it is and what it
1:00:01does all right so the first thing we can
1:00:02do is we can just use the waters command
1:00:04to give us a bit of a context or
1:00:06information in in regards to what this
1:00:07tool is and what it does so again it
1:00:09tells you
1:00:10this prints lines matching a particular
1:00:12pattern and again if you're interested
1:00:14in learning more about the tool you can
1:00:15always use the manual pages or go
1:00:17through the manual pages for the
1:00:19particular tool so there you are it
1:00:20gives you information or in regards to
1:00:22how to use it the purpose of this video
1:00:24is to show you how to use it in the most
1:00:26efficient way or in a way to therefore
1:00:28in increase your understanding on on how
1:00:31to use the tool
1:00:32and how to make you efficient with using
1:00:34it
1:00:34all right so uh before we we actually
1:00:37take a look at a concrete example of how
1:00:39to use grep
1:00:40we must understand two things all right
1:00:42the first thing you need to understand
1:00:44is there are two ways of using grip the
1:00:45first way is by using grip on its own
1:00:47all right so again we can just type in
1:00:50grep here
1:00:51uh and the other way of using grip is by
1:00:53actually piping the output of another
1:00:55command into grep and then finding what
1:00:57you're looking for all right so you
1:00:59might be a little bit confused but let
1:01:00me explain what it does in a very simple
1:01:02way so grep is a tool that allows you to
1:01:04find strings or patterns in files
1:01:06alright so that means you can search or
1:01:08specify for the data or the strings
1:01:10you're looking for in a particular file
1:01:12all right so let's take a look at a com
1:01:14at a concrete example uh we're going to
1:01:16be looking for a word within a the
1:01:19proxychains.configuration file now if
1:01:21you're not familiar with what
1:01:22proxychains is uh you can check out my
1:01:24proxy change video where i show how to
1:01:26set it up uh and install it but again
1:01:28it's it really doesn't matter because
1:01:30you can follow up with any other files
1:01:32you're working with all right so let's
1:01:34say i
1:01:35i wanted to find the word dynamic within
1:01:37the file the cro the proxy chains
1:01:39configuration file
1:01:41let's let's take a look at how to use it
1:01:43using the first method which is using
1:01:44grep on its own without piping the
1:01:46output of another command so we can say
1:01:48grep and then the command we want to
1:01:50specify after or the parameter
1:01:52or the variable rather is the the data
1:01:54we're looking for so again you want to
1:01:56encapsulate this within double quotation
1:01:58marks so again if it's a word we can
1:01:59type in dynamic now the thing you you
1:02:02must ensure is that this this search
1:02:04will be case sensitive and i'll show you
1:02:06how to omit at the case sensitive
1:02:07searches so let's say we're looking for
1:02:09the uh the the word dynamic and then we
1:02:12specify the location of the file we want
1:02:14to search
1:02:15for this particular word in so again
1:02:17proxychains.conf
1:02:19and again we can use the double tab here
1:02:21like so and we hit enter and again that
1:02:23displays the word dynamic chain to us
1:02:26again that's the the word that it was
1:02:28able to find within the entire file
1:02:31however as i said this say
1:02:34this particular search is going to be
1:02:35case sensitive now if we want to omit
1:02:38the case sensitive search we can use the
1:02:40i parameter or the i argument here
1:02:43so once we hit i that means that it will
1:02:46search for all files
1:02:48or for all words within this particular
1:02:50file uh
1:02:52called a dynamic all right so once we
1:02:54hit enter you can see now it gives us
1:02:56two lines in the files uh they are both
1:02:58different in the fact that the first one
1:03:00is in case and the second one starts
1:03:02with an uppercase d all right so again
1:03:05it's a very simple tool to to use and
1:03:07again you can now see how efficient and
1:03:09how great it is at finding bits of
1:03:11information within files so again we can
1:03:14say let's say we want to look for
1:03:16particular users within the password
1:03:18file so i can say grep
1:03:20and i can say let's say we're looking
1:03:22for the user alexis in the password file
1:03:24and then i say etsy
1:03:26password and we hit enter and then it
1:03:28displays the user account information
1:03:30for the user lexis all right so that's
1:03:32very simply how to use it now let's take
1:03:34a look at the second method or way of
1:03:37using grep and that's by piping the
1:03:39output of one command
1:03:41into crep and then of course finding the
1:03:43data you're looking for that way and the
1:03:45way to do this is by using the pipe the
1:03:48pipe symbol or the pipe key on your
1:03:50keyboard now you can find this key on
1:03:52the extreme right of your keyboard just
1:03:54before your numpad if you do have one
1:03:57all right so the way we use it is let's
1:03:59say we wanted to cut the contents of the
1:04:01password file so let's say we wanted to
1:04:03say cat etsy
1:04:06password and we say we want to look for
1:04:09a particular string within this file and
1:04:12to do this with grep we now enter the
1:04:15pipe symbol
1:04:16which means we are redirecting the
1:04:18output of this initial command
1:04:20and we are now passing it on to grep so
1:04:22now grep can do something with this
1:04:24output so we say grep i want you to look
1:04:26for the word dynamic all right
1:04:29and we type we hit enter and we and
1:04:31there you are so again it does not give
1:04:33us any options here um and that's
1:04:36because i did not specify user here so
1:04:38again say alexis and again that gives us
1:04:40the using the user account information
1:04:43for the user lexus and again we can just
1:04:45change it to the
1:04:46proxychains.configuration file here
1:04:48and we hit enter and we change this to
1:04:50dynamic sorry um like so and it gives us
1:04:53the data now a lot of people have been
1:04:55asking me since uh since i covered
1:04:58redirecting output uh as i mentioned
1:05:00there are two ways of redirecting output
1:05:02the pipe
1:05:03key or the pipe command is used to
1:05:05redirect output and you know further
1:05:07process the data that you're outputting
1:05:09the difference between the pipe uh the
1:05:11pipe uh command or redirecting output
1:05:14with pipe and the greater than symbol is
1:05:15the greater than symbol will not display
1:05:18the information on to your terminal it
1:05:20will actually just output everything or
1:05:23redirect all the output of the command
1:05:25that you have
1:05:26that you've used into a file or even
1:05:28another command so again if i say cat
1:05:31fc password and i use this i wanted to
1:05:33redirect the output into it uh into a
1:05:35txt file i can say desktop
1:05:38and say test.txt and i hit enter and now
1:05:41if i actually get uh the the the file on
1:05:44my desktop sorry i believe i'm in my
1:05:46home directory here and i say test.txt
1:05:48hit enter it it actually has the content
1:05:50of the file so again that's the
1:05:51difference when uh when i'm actually
1:05:53talking about uh redirecting output with
1:05:56both the pipe and the greater than sign
1:05:58uh which is very different so
1:06:00again the pipe symbol is the preferred
1:06:02way of using or actually passing the
1:06:04output of one command and processing it
1:06:06with another command
1:06:08like
1:06:08leg grip and you can use it with other
1:06:10utilities that will actually show you
1:06:11how to use uh for the further further
1:06:14along the series here
1:06:16so
1:06:17you can use this with any other command
1:06:18that displays output onto the screen so
1:06:20i'm just going to use one more command
1:06:22just to show you how efficient this is
1:06:23so let's say i typed in ifconfig and i
1:06:26just want my inet information i can pipe
1:06:28the output of the ifconfig command and i
1:06:30can say i net
1:06:32uh and i can just say grab i net here
1:06:34and i hit enter and it gives a it gives
1:06:36me my inet information whether that be
1:06:38ipv4 or ipv6 all right so you can now
1:06:41see how useful this is and i want you
1:06:44guys to experiment with this let me know
1:06:46what you think
1:06:47where you're not understanding how to
1:06:48use it and i'll be sure to make up for
1:06:51full follow-up videos if you guys are
1:06:52interested in it
1:06:56in this video i'm going to be showing
1:06:58you how to use the locate utility to
1:06:59find files and i'll be also making an
1:07:02another video after this to show you how
1:07:03to use the find tool to actually find
1:07:06files as well so they're two utilities
1:07:07that you can use in this video we're
1:07:09going to be taking a look at how to use
1:07:10the locate tool it's a tool that goes
1:07:12ignored by many beginners or newcomers
1:07:14mostly because of its relative
1:07:15simplicity but it's a very efficient
1:07:17tool and does what it's supposed to do
1:07:19so again
1:07:20we can use the what is uh utility here
1:07:22to tell us more about what this tool is
1:07:24so again we can just say what is locate
1:07:26and as you can see it tells us it finds
1:07:28files by the name which is very simple
1:07:30and again you can use the manual page
1:07:33you can use the manual for this
1:07:34particular tool to learn how to use it
1:07:36so i'm just going to be covering just
1:07:38enough to make you efficient with the
1:07:39tool and make you understand how it
1:07:41works and how you can use it in
1:07:42conjunction with grip
1:07:44all right so
1:07:46uh let's actually get started with a
1:07:48very simple example right so let's say i
1:07:50wanted to locate a file on the system
1:07:52right and
1:07:53i wanted to locate a the password file
1:07:56so i can say locate
1:07:57password and hit enter and you can see
1:08:00it's given me a lot of a lot of
1:08:02information here a lot of files called
1:08:04password on my system
1:08:05right now this is really not efficient
1:08:08because um again i'm looking for a
1:08:11particular file that i'm looking for
1:08:13which is bill which actually exists in
1:08:14the etsy file and we can see the result
1:08:17well that's not actually the result here
1:08:19with this is the result right at the top
1:08:20here all right however this really is
1:08:23not efficient or an efficient way of
1:08:24going about it right so uh this is where
1:08:27we can now specify the options that we
1:08:29can use
1:08:30uh that we can use with uh with a tool
1:08:33like locate so let's say we wanted to
1:08:36get only the files that match this
1:08:38particular pattern or these particular
1:08:40uh strings here so the password string
1:08:43so to do this we type a or we use the uh
1:08:45we can use the all parameter or option
1:08:48here and once we hit enter again that
1:08:50gives us the same information so what
1:08:51does that means is it's actually
1:08:53displaying all the files on the system
1:08:56uh that actually match the patterns of
1:08:58password here
1:09:00and because this file really doesn't
1:09:01have any extension we now have to deal
1:09:03with the actual path or the path that we
1:09:06we might want to be uh finding this file
1:09:09in now of course that is counter
1:09:11intuitive given that um
1:09:13i can say that this belongs in the etsy
1:09:15in the etsy directory and again that now
1:09:18it now actually narrows down uh the
1:09:20files into what they may be so again
1:09:22that's the the actual file where we were
1:09:24looking for but you can see how tedious
1:09:26this is so we can actually shorten this
1:09:29now by actually using the grep tool
1:09:31which actually showed you how to use and
1:09:33it's very very simple so again we're
1:09:35simply going to use grip to look for
1:09:37particular information related to the uh
1:09:40to the information that is is given to
1:09:42us by locate so we can now say locate
1:09:45and then we say we're looking for
1:09:47password and
1:09:49we close that and now we say we pipe the
1:09:51output and we say grip let's look for
1:09:54password uh within etsy within the etsy
1:09:58directory so again
1:09:59we can now say etsy here sorry fc and
1:10:05we say password or we can just say the
1:10:07etsy directory here and then we can hit
1:10:09close and you can see it gives us the
1:10:11results we're looking for it highlights
1:10:13them in red or depending on the color
1:10:15scheme you're using in your terminal so
1:10:16again we can improve the efficiency of
1:10:18this by typing in
1:10:20etsy password and we hit enter so this
1:10:23is a file without a particular extension
1:10:25which makes it relatively difficult to
1:10:27actually find but you can find it
1:10:29relatively easily if you use grep here
1:10:31um so so let's actually talk about um
1:10:34about another file that has an extension
1:10:35that we can use to explain this here
1:10:38all right so
1:10:40um let's say we're working with the
1:10:43the the resolve file or the resolve
1:10:46configuration file which is used for to
1:10:48modify your name servers which is
1:10:50available on our linux systems what we
1:10:52can say is we can say locate
1:10:56resolve and uh sorry resolve and we hit
1:10:58enter and again tons of files but now we
1:11:01know that this file has an extension so
1:11:03we can say uh locate it's uh we can say
1:11:05locate resolve uh dot conf and read
1:11:08enter and again it still gives us a lot
1:11:09of files but we're looking for the one
1:11:11that belongs in the that exists in the
1:11:13etsy folder again so what we can do now
1:11:16is we can say locate and we want to
1:11:18actually
1:11:20we're looking for we can use the all uh
1:11:22the old parameter here
1:11:23and then we say we're looking for
1:11:26uh all files with an extension or we're
1:11:29looking for a file with the with an
1:11:30extension of uh conf or config here so
1:11:34we'll use the wildcard option to mean
1:11:36that this we're looking for for all
1:11:38files with this particular extension so
1:11:39we say
1:11:40um all and then we say conf and we close
1:11:44those um these quotation marks and now
1:11:46we pipe the output into grep here and
1:11:48now with grep we can then say we are
1:11:51looking for resolve here and we sorry
1:11:53that is we're looking for resolve when
1:11:55we enter and now it gives us the
1:11:57information we're looking for
1:11:59and the first option here so again
1:12:01that's with the
1:12:02the actual extension of confirm so again
1:12:04we're limiting the results to
1:12:07only the files that have an extension of
1:12:08config or configuration and then we can
1:12:10use grep to find the particular string
1:12:13that is most important to us so let me
1:12:15give you another example because this
1:12:16seems very simple
1:12:18so let's say
1:12:20we're looking for the proxy chains right
1:12:23uh so we can say proxy change and hit
1:12:25enter and there you are you can see
1:12:27immediately now because that is a unique
1:12:29string it gives us the results
1:12:31immediately with the uh we with the uh
1:12:33the extension here and that's because we
1:12:35specified it so again we can just say
1:12:37locate you know proxy chains
1:12:40and hit enter and there's a ton of files
1:12:42now another thing you might find useful
1:12:44is actually
1:12:46displaying how many results are matching
1:12:49the particular pattern you have
1:12:50specified exist so let's say i want to
1:12:52say locate i can say all that means all
1:12:55the the the matching uh the matching
1:12:58patterns here so we say all and then we
1:13:00can use the c uh the c argument here
1:13:03which specifies or prints the number of
1:13:05matching results and then we say we
1:13:08specify the string we're looking for or
1:13:10we can just say we're looking for proxy
1:13:12chains and we enter and it tells us here
1:13:14that we have 25 uh files
1:13:17uh or results that actually have the
1:13:19matching patterns here now if we limit
1:13:21it to
1:13:22conf and we hit enter now you can see we
1:13:24only have two so that's essentially how
1:13:26to use this tool uh in regards to you
1:13:28know displaying the amount of matching
1:13:30uh patterns you have and if you wanted
1:13:32to locate so if we get rid of this here
1:13:36and let's hit enter you can now see the
1:13:37results that it tells us here so we have
1:13:39the one in the etsy folder and one in
1:13:42the the debian package management uh
1:13:45the debian package management folder uh
1:13:47in regards to its actual configuration
1:13:50there so
1:13:51that's how to use the locate tool now
1:13:52again let me just cover one more
1:13:54additional parameter you can use and
1:13:56that is the the eye parameter which
1:13:58again is very important and that means
1:14:00that you want to ignore case uh that's
1:14:02something i should have mentioned
1:14:03earlier all searches with locate are
1:14:05typically going to be case sensitive so
1:14:08again i can say proxy chains
1:14:10and i hit enter and we have no results
1:14:12right so if i wanted to ignore the case
1:14:14sensitivity of what i've just hit uh of
1:14:16the the pattern i've just entered i can
1:14:18just hit i and i'd enter and again we
1:14:20get the same results and i can now limit
1:14:22this to proxychains.conf and there you
1:14:24are and again i can i can partner these
1:14:26or i can actually combine these commands
1:14:28with each other to give us the
1:14:30information we're looking for so again a
1:14:32very very simple tool to use but again
1:14:34it gives you very consistent results
1:14:40in this video we're going to be taking a
1:14:41look at how to enumerate uh system
1:14:43information on linux now you might be
1:14:45wondering what exactly do you mean here
1:14:47well i'm simply referring to uh
1:14:49important information about your system
1:14:51and the user currently logged in as just
1:14:54information that you might need when
1:14:56you're currently logged onto a system
1:14:57and you might want to know more about
1:14:59what you're dealing with all right so
1:15:00let's get started now the first
1:15:03uh the the first thing we need to do is
1:15:05we need to find out what user we're
1:15:07currently logged in as and the host name
1:15:09and the use id etc etc all right so
1:15:13let's get started with that
1:15:15so the first thing i want to know when
1:15:17i'm logged in is who am i exactly and
1:15:20that tells me the current user that i'm
1:15:21logged in as and then if i type in host
1:15:23name
1:15:24uh that again gives me the current
1:15:26hostname of this workstation or of this
1:15:28computer in my case it tells me i'm
1:15:30running uh the hostname is alexis
1:15:32workstation now if you do want to change
1:15:34your uh your hostname you can you can do
1:15:38so by by modifying the host name file i
1:15:41believe that's what it's called the yeah
1:15:44there we are and you can see that mine
1:15:46is set to alexis workstation or ws which
1:15:49is an abbreviation of workstation so you
1:15:51can change this and in my case i don't
1:15:53want to do this so i'm just going to
1:15:54exit out of here
1:15:56so that is how to find out the current
1:15:58user logged in as and the host name
1:16:01now if you want to find the user id that
1:16:03you're currently logged in as you can
1:16:04simply type in id
1:16:06that gives you the current use id
1:16:09and again of course the user you then
1:16:10have the group id which is quite
1:16:12important and the other groups that this
1:16:13user is currently a part of
1:16:15now um
1:16:17in regards to groups and the groups that
1:16:20a particular user may be part of the way
1:16:23to enumerate this information is by
1:16:25typing in groups and then the name of
1:16:27the user so we can type in groups alexis
1:16:30and once we hit enter again it tells us
1:16:33the user lexis is a part of these groups
1:16:35so it's a part of the group alexis sudo
1:16:38among the other ones here that are
1:16:40essentially system uh system accounts
1:16:42here that you or system groups that uh
1:16:45really have to do with just permissions
1:16:47to a particular service
1:16:49um so that is basic user enumeration now
1:16:51let's talk about a little bit about the
1:16:53system and enumerating information like
1:16:56um
1:16:57like your uh
1:16:59like your linux distribution the version
1:17:01stuff like that so uh i'm currently
1:17:03using a debian system or i'm using
1:17:06ubuntu so again it's based on debian so
1:17:08the the practices are all the the
1:17:10techniques and the commands are quite
1:17:12similar on both ends now when dealing
1:17:14with uh you know systemd based
1:17:16distributions
1:17:17uh and all of course red hat based
1:17:18distributions the process is going to be
1:17:20slightly different and i'll explain why
1:17:22and how
1:17:23um so on linux if you on sorry on
1:17:27on on tpn or on ubuntu if you want to
1:17:29enumerate your linux uh if you want to
1:17:32enumerate your linux distribution
1:17:34version and the name you simply type in
1:17:37lsb release a and of course
1:17:40lsb is a utility and you may not have it
1:17:43installed but again it comes with um
1:17:46with db and ubuntu by default so again
1:17:49that tells us the distributor the
1:17:50distributor id the description again
1:17:53ubuntu 18.04
1:17:550.3 lts
1:17:57the release name
1:17:58sorry the release version and the code
1:18:00name here which in this case is bionic
1:18:02beaver
1:18:03so again you can also use the check the
1:18:05contents of the issue file
1:18:08so if we type in cat etsy issue you can
1:18:10see it tells us the same thing here
1:18:12um
1:18:14so that is for debian based
1:18:16distributions now um
1:18:18when dealing with system d distributions
1:18:21like um
1:18:23centos arch
1:18:25red hat
1:18:27also debian to to some extent you can
1:18:29also use the you can also take a look at
1:18:32the content within the os release
1:18:34file which will also enumerate on debian
1:18:36as well but i just wanted to explain
1:18:38that so you guys don't get confused all
1:18:40right so what you can do is just simply
1:18:42type in cat let's see
1:18:44os
1:18:46os release and again that gives us the
1:18:47information that we were looking for now
1:18:50on um on ubuntu and on db and if i hit
1:18:53enter it tells us nothing there if i
1:18:56then use the star or the wildcard we hit
1:18:58enter that gives us the linux
1:19:00distribution information
1:19:02and a bit more information regarding the
1:19:04privacy policy
1:19:06uh support url stuff like that
1:19:09and um now that's uh now that we've also
1:19:12covered the system the uh base
1:19:14distributions let's talk about uh
1:19:16dealing with red hat now on red hat um
1:19:18if you want to take a look at the
1:19:20uh the red hat release version uh you
1:19:23can i believe you can find it if i type
1:19:24in cat hc and then you type in red hat
1:19:28release now i'm currently not using a
1:19:30red hat based distribution so that would
1:19:32pretty much give you the red release
1:19:34version um so that's basically
1:19:36enumerating your distribution name uh
1:19:40your distribution version and name um if
1:19:42you are using you know some of these uh
1:19:45distributions based on debian or the
1:19:47systemd based distributions like arch
1:19:50centos or red at enterprise linux
1:19:53so again let's talk about you know
1:19:56enumerating information about your
1:19:57processor or your cpu
1:19:59so you can easily do this by typing your
1:20:01ls cpu and we can hit enter and again
1:20:03that enumerates information about your
1:20:05cpu so it gives you information like
1:20:07your architecture and the instruction
1:20:09set
1:20:10um the amount of uh the amount of cores
1:20:14the threads per core the cost per socket
1:20:17sockets
1:20:18vend id
1:20:19cpu family the model model name in this
1:20:22case it's an i5 8400
1:20:25uh the stepping the
1:20:27the
1:20:28frequency here in megahertz so max and
1:20:31minimum as well so 4 gig by 4 gigahertz
1:20:34and the minimum of 800 megahertz
1:20:36uh
1:20:38virtualization and then the l1 l2 and l3
1:20:41cache and so information about your cpu
1:20:44all right so now that we've taken a look
1:20:47at enumerating cpu information let's
1:20:48take a look at enumerating kernel uh
1:20:50information which is done using the you
1:20:52name
1:20:53uh
1:20:54using the unnamed command or utility
1:20:55which essentially stands for unix name
1:20:59so again if we just type in what is your
1:21:01name here and you can see it says prints
1:21:03system information and guess the name
1:21:05and information about the current uh
1:21:07kernel so using it is very very simple
1:21:09so if you type in your name a that
1:21:11displays all the information so again it
1:21:13gives you information about like your uh
1:21:15your host name the current linux kernel
1:21:17that's that's installed and currently
1:21:19running
1:21:20and then you have the uh you then have
1:21:23the instruction set here i'm going over
1:21:24the the important information so again
1:21:27we can uh we can actually take a look at
1:21:29the various options that are available
1:21:31here so again we can say
1:21:33if we want the kernel uh we if we want
1:21:36the kernel version here we can type in
1:21:38uh we can say you name
1:21:41s and that tells us the kernel that
1:21:43we're currently running which is the
1:21:44linux kernel the version here can be
1:21:47printed out by typing you name
1:21:49uh i believe it's your name r that's the
1:21:51current release so in our case it's
1:21:53version 4.15 which i believe is stable
1:21:57not too sure
1:21:58um and then if you want again if you
1:22:00want the
1:22:03the information about the the
1:22:04instruction set for your processor you
1:22:06can type in your name
1:22:08you name p
1:22:09again that gives you the instruction set
1:22:10in our case x 86 64.
1:22:14uh and then if we want the hardware
1:22:16platform we can type in you name i
1:22:19so we can say you name i
1:22:21the hardware platform again that's the
1:22:23that's uh the information in regards to
1:22:25the architecture and then the operating
1:22:28system
1:22:29uh we can say you name
1:22:31o and it enter gnu linux so again just
1:22:33basic information regarding your system
1:22:36but uh the key bits of the important
1:22:39pieces of information here are your
1:22:40kernel and the instruction set of course
1:22:43so that's essentially all the
1:22:45information uh that you might want to
1:22:48enumerate regarding your system or you
1:22:50might be interested in now dealing with
1:22:53um with disk usage and um disk uh and
1:22:57disk usage disk space i'll be making a
1:22:59separate video on that so uh you guys
1:23:01can stay tuned for that but in regards
1:23:03to your system this these all the
1:23:05commands that you can use to find
1:23:06information about your the current user
1:23:08that's logged in
1:23:10uh so again if i type in who again that
1:23:12tells me the current users that are
1:23:14logged in in my case it's uh the only
1:23:17user is alexis so that's just an
1:23:19additional tidbit so again we've covered
1:23:22you know the user id the group id and
1:23:26we've also covered enumerating
1:23:27distribution information and the kernel
1:23:29information so
1:23:34in this video we're going to be covering
1:23:35how to use the find tool and we'll also
1:23:37be taking a look at some challenges on
1:23:39of the wire bandit uh more related to
1:23:41what we're taking a look at in this
1:23:42video which is how to correctly utilize
1:23:45the find command to look for files or
1:23:46directories within your system so an
1:23:48extremely uh you know very useful tool
1:23:51that will really help you save time when
1:23:53looking for particular files and i'll be
1:23:55showing you how to use it right now most
1:23:56efficiently so again we can use the what
1:23:58is utility to find out more information
1:24:00about the tool so again it tells you at
1:24:02this this tool allows you to search for
1:24:04files and in a directory hierarchy you
1:24:07can also check out the man pages for
1:24:08this particular tool
1:24:10and again you can go through all of this
1:24:12if you want to i'm going to be covering
1:24:14all uh the the information that is
1:24:16necessary or that will make you the most
1:24:18efficient with this tool
1:24:20all right so let's get started let's
1:24:21stop wasting time so using the tool is
1:24:23very simple we say find and then after
1:24:25sayings find we need to specify uh the
1:24:28directory we want to we want to search
1:24:30in so again we can specify the current
1:24:32directory that we are currently in uh by
1:24:34you know using the full stop or the dot
1:24:37uh or we can specify the entire linux
1:24:39file system directory which is done by
1:24:41using a forward slash like so as you
1:24:43would when navigating directories
1:24:45or i can specify an individual directory
1:24:47that i want to uh that i want to search
1:24:49in so i can say home
1:24:51alexis which is pretty much the
1:24:52directory we're working in so what i'm
1:24:54going to do is i'm just going to search
1:24:55the entire linux file system directory
1:24:57which if you're going to do you do
1:24:58require root or pseudo privileges
1:25:00otherwise you'll not be able to access
1:25:02files and directories that you know you
1:25:04do not have adequate permissions to
1:25:05access
1:25:06so i will also add the pseudo command
1:25:09here
1:25:10so again we're going to find files
1:25:11within the linux file system directory
1:25:13we then specify the other bit of
1:25:15information that uh will help us
1:25:16fine-tune our results which is of course
1:25:18going to be the type that we're dealing
1:25:20with so the type in regards to the find
1:25:22command is very simple it simply refers
1:25:24to what you're dealing with so are you
1:25:26looking for a file or a directory and
1:25:28that can be denoted by either using f
1:25:31for file or d for directory in our case
1:25:33we're looking for a file so we're just
1:25:35going to hit file all right so very
1:25:37simple next we specify the other
1:25:39variable that again will help us
1:25:40fine-tune our search results and is very
1:25:43important which is the name so what is
1:25:45the name of the file you're looking for
1:25:46so i can say proxy chains
1:25:49and i know i'm using the same example
1:25:51but again i'll show you how robust this
1:25:53is in a second so i can say
1:25:54proxychains.conf
1:25:56and after this i can pretty much hit
1:25:58enter now the important thing to note
1:26:00here
1:26:01is that i can use uh the grep command in
1:26:03conjunction with find to you know pipe
1:26:05output and specify configuration files
1:26:07by themselves similar to what we looked
1:26:09at when we're taking a look at the
1:26:10locate tool uh so i can just hit enter
1:26:13and you can see we found the
1:26:14configuration file and we didn't have
1:26:17adequate permission for some files which
1:26:19is perfectly fine
1:26:20um so that's how to use the find tool
1:26:22and i've shown you the various
1:26:23parameters you can use so you can
1:26:24specify the type uh the name uh which
1:26:27i'll show you how to how robust it can
1:26:28be in a second so let's take a look at
1:26:30the same example so i'm just going to
1:26:32say find um and you know we can just say
1:26:35sudo sudo find
1:26:37and we say the type is going to be
1:26:40a file which you can also change to
1:26:42directory if you are looking for a
1:26:43directory so for example i can say
1:26:46directory and then i can say name
1:26:48and their name is going to be alexis
1:26:50look for the directory lexis and hit
1:26:52enter and their ui tells us oh we have
1:26:54various uh directories here so we can
1:26:56see we have um
1:26:58we have the home directory here and a
1:27:00few other files here that uh i've
1:27:02actually popped up from my external hard
1:27:04drive which i don't think are that
1:27:05important
1:27:07but there you go that just shows you how
1:27:09robust this tool is in regards to you
1:27:11know looking for particular files so you
1:27:13can change that up so so let's go back
1:27:14to our previous example so i'm just
1:27:15going to say the name is going to be
1:27:17proxy chains now i mentioned in the
1:27:19previous video the the case sensitivity
1:27:21which is quite important so if you are
1:27:24performing a search
1:27:26uh in which you do not want any case
1:27:28sensitivity you use the i name command
1:27:30instead of the name command and then
1:27:32after this you can say i can say alexis
1:27:34for example and of course it will ignore
1:27:36all the cases here so i can you know i
1:27:39can combine it with whatever uppercase
1:27:41up and lowercase uh characters i want
1:27:43and i'll still get i'll still get the
1:27:45same results
1:27:46uh and i can just hit enter
1:27:49and uh this time again it gave us uh the
1:27:52same results but uh it gave us different
1:27:54results because we are looking for a
1:27:56file so if we change this into a
1:27:57directory here you can see that it's
1:27:59going to give us the same results that
1:28:00we had in the in the initial run when
1:28:02we're looking for uh you know
1:28:04directories uh called alexis so that's
1:28:06how robust this tool is so i talked
1:28:08about using um using extensions which is
1:28:11again very very simple so let's say
1:28:13we're looking for extensions and we're
1:28:15looking for all uh conf files which
1:28:17belong in the etsy directory so i'm just
1:28:19going to say etsy and we've now written
1:28:21it down we can say name is going to be
1:28:24i can say um
1:28:27uh we can just say conf and we'll use
1:28:28the wildcard uh so i say conf we'll just
1:28:31use the same configuration file
1:28:32extension
1:28:33uh and then i can say grep and then i
1:28:35specify the name of the file right so uh
1:28:38you know i can hit enter and this is
1:28:40going to display all the configuration
1:28:42files within the etsy directory but
1:28:44again i have to specify the
1:28:46uh the file specification here and i'm
1:28:48going to enter
1:28:49and there you are so it gives you all
1:28:50the configuration files so very simple
1:28:53tool to use now let's talk about the
1:28:54other variables that you can use to
1:28:56specify
1:28:57that will help you fine-tune your your
1:28:59search results and that is by specifying
1:29:01the size of the file
1:29:03and the permissions all right so again
1:29:05we can just use a simple example i'm
1:29:07just going to say find and i'm going to
1:29:09say we'll say type and that's going to
1:29:11be you don't really need to specify the
1:29:13type if you don't want to it's just
1:29:14there to help you fine tune your results
1:29:16so i can perfectly ignore it if i know
1:29:18what i'm looking for
1:29:19precisely i can then say you know name
1:29:22and the name is going to be proxy chains
1:29:25i can say epoxychains.conf you know i
1:29:26have the whole name
1:29:28and then i can say size i'm looking for
1:29:30a file with a particular size so i can
1:29:32then use the various options i have so i
1:29:34can say it's going to be plus one
1:29:36megabyte which can be done like so uh or
1:29:39i can you know i can save plus a hundred
1:29:41megabytes whatever i want to say so in
1:29:43this case let me just say plus one
1:29:44megabytes and hit enter
1:29:46and uh well we're getting uh various
1:29:48permission errors here and that's
1:29:50because we'll just say etsy
1:29:52hit enter
1:29:54and i will say sudo and
1:29:57there we are and we got no results at
1:29:59all i just wanted to to actually provide
1:30:01it with the adequate the adequate
1:30:02permissions so that i can show you that
1:30:05if we use uh you know
1:30:07if we use parameters like these size and
1:30:10we specify it down to due to the actual
1:30:13size of the file we can sort of uh
1:30:14fine-tune our results very very uh to a
1:30:16very deep granular level
1:30:18so if i just um
1:30:21let's say um etsy and i can then grab
1:30:26proxy chains
1:30:28conf and
1:30:29i hit enter here you can take a look at
1:30:32let me just change this to a human
1:30:34readable format so you can say it's
1:30:36about uh four kilobytes here and uh we
1:30:39can then you know you can specify the
1:30:41size depending on on how you want it and
1:30:43i'll get back to this uh when we'll be
1:30:45taking a look at the uh the over the
1:30:46wire banded challenges because that's
1:30:48where i really want to showcase the
1:30:49power of the fine tool
1:30:51let's talk about permissions before we
1:30:53actually get started with at the over
1:30:54the wire bandit challenges and the
1:30:56permissions are very simple to to
1:30:58actually specify here i'm going to be
1:31:00covering you know users and groups and
1:31:01we'll be taking a look at that example
1:31:03but let's talk about uh permissions
1:31:05first so permissions allow you to find
1:31:07again files that have particular
1:31:09permissions very very straightforward
1:31:11here so you know i can say um
1:31:14let's say i create a file go to my
1:31:16desktop here and i'll say touch
1:31:18alexis dot sh you know just a simple
1:31:21shell script or a bash script here hit
1:31:23enter and i say chmod
1:31:25400 alexis dot sh and hit enter and they
1:31:29say find within
1:31:30the home directory i can then say
1:31:34let's say we're looking for a file
1:31:36type is going to be a file we don't have
1:31:38a name but we have permissions so i can
1:31:40say firm
1:31:41let's look for
1:31:43let's look for files with the permission
1:31:44of 400 which means
1:31:47um
1:31:48which means that the the the owner or
1:31:50the user can read the file um but the
1:31:53other group and all other users on the
1:31:55system are not able to access it so
1:31:58again uh that should give us a few
1:32:00results but we don't have adequate
1:32:01permissions for the other files so you
1:32:03can see we get the result right over
1:32:05here so you can use permissions to help
1:32:07fine-tune your search results and get
1:32:09the exact results you're looking for
1:32:11you know we can also specify 744 we hit
1:32:14enter and uh
1:32:16it looks like we had a few files with
1:32:18those particular permissions but
1:32:20nothing no no important files that we
1:32:23that don't have the correct permission
1:32:25so you can see that this can help you
1:32:26find a files on your system that have
1:32:28incorrect permissions and then you can
1:32:30rectify them uh you know like so instead
1:32:32of going manually and checking for their
1:32:34permission so very useful tool now that
1:32:36we've taken a look at how to use the
1:32:38tool let's take a look at how to
1:32:40implement it in some challenges and
1:32:42that's what we're going to do in the
1:32:43next step which is the over the wire
1:32:45challenges so you can follow along if
1:32:46you want to and i'll see you there
1:32:48all right so we are back on over the
1:32:50wire and i'm currently on the bandit uh
1:32:53on the bandit web page here and uh you
1:32:56you can get access to this challenge by
1:32:58following the instructions on level zero
1:32:59uh the levels we're interested in are
1:33:01going to be levels four five
1:33:03uh level fours uh to level four to level
1:33:06six so again we'll just go to level four
1:33:08here and i currently have access and
1:33:09i've solved the challenges uh all
1:33:12all up till level four so we can get
1:33:14started
1:33:15all right so
1:33:16uh you can see that uh level four
1:33:18pertains uh
1:33:20actually finding a file so you can see
1:33:22the password for the next file or for
1:33:24the next level is stored in the in the
1:33:26only human readable file
1:33:28in the in here directory uh tip if your
1:33:31terminal is messed up you can try the
1:33:33reset command and again it gives you the
1:33:35various commands that you can use to
1:33:36solve this level so again let's go back
1:33:38into our terminal as you can see i'm
1:33:40currently on bandit 4 and we can list
1:33:42the files within this home directory and
1:33:44you can see we have an in here directory
1:33:46so let's uh let's go in here let's see
1:33:48what's going on
1:33:50so if you list the files here you can
1:33:52see we have various files and if i if i
1:33:54try cutting one of these uh one of these
1:33:56files you can see that um
1:33:59sorry let's specify that hyphen there
1:34:02let's say file zero zero we can hit
1:34:04enter and you can see it has a various
1:34:06uh
1:34:07it has various pieces of data and of
1:34:09course our job is to look for files
1:34:11within this in here directory that have
1:34:14uh human readable data so again what we
1:34:16can do is we can use the find command
1:34:18here uh to actually find uh you know the
1:34:21various files that have human readable
1:34:23data so i can say uh in this current
1:34:25directory and we are looking for um
1:34:28[Music]
1:34:29we can actually just say find and then
1:34:31in this directory uh we're looking for
1:34:34the type
1:34:35it's going to be a type of file here and
1:34:37then we can grip the output or we can
1:34:39pipe the output sorry and within we can
1:34:41use the x args command here to look for
1:34:45um i believe it's uh if we just expand
1:34:48this uh let's take a look at how to use
1:34:50x cogs one more time
1:34:51uh we wanted to display uh the file read
1:34:54items from a file uh instead of standard
1:34:57uh standard input
1:35:00uh
1:35:00and yeah this if we type in file that
1:35:03should tell us the files that we're
1:35:04dealing with all right and this will
1:35:06help us shorten the process so let's go
1:35:08back in here as we say file in it enter
1:35:11and as you can see it tells us that in
1:35:13file 0 7 we have some ascii text however
1:35:17in all the other files we have data so
1:35:18again we can access this file now we can
1:35:20just cap the contents of this file and
1:35:22we should get the password next level
1:35:24all right excellent so we can copy this
1:35:26let me exit and we'll go to bandit level
1:35:29five here i'm going to enter we'll just
1:35:32paste in the password
1:35:34and we can get started now all right so
1:35:36let's take a look at what a challenge or
1:35:38level five uh pertains
1:35:40so again it says the password for the
1:35:42next level is stored in a file somewhere
1:35:44under the in here directory and has all
1:35:47of the following properties it's human
1:35:49readable um okay all right it's going to
1:35:52be a human readable file um 1033 bytes
1:35:56in size
1:35:57and it's not executable all right so
1:35:59that's uh an option these are all the
1:36:01these are all parameters that we'll have
1:36:03to specify to some extent
1:36:05so let's actually get started so
1:36:07uh these are going to be in the in here
1:36:10directory so i'll just go into the in
1:36:11here directory and you can see we have
1:36:13uh other directories within this so
1:36:15we're going to just say find
1:36:17uh and we're going to say type is going
1:36:19to be a file uh we were told that we
1:36:22have it's going to be human readable so
1:36:24you can use x args there
1:36:27uh
1:36:27size i showed you how to specify size
1:36:29now the the thing about specifying size
1:36:32in bytes is if we just take a look at um
1:36:37we take a look at the at the find tool
1:36:38and we just
1:36:40grip for some for size you can see that
1:36:43it tells us the size does not count
1:36:45indirect blocks uh
1:36:47etc so size one megabyte is not
1:36:49equivalent is not equivalent to size so
1:36:51if you're specifying it in bytes you
1:36:53need to specify uh the actual number and
1:36:55then the c here all right so that's what
1:36:58we have to do so um we just go back in
1:37:01here and we go to type a file and then
1:37:03we say size
1:37:04is going to be 10 33 c and then after
1:37:07this um
1:37:09we're supposed to us
1:37:11the file is not
1:37:12is not executable so we can then use the
1:37:15logic um operators here so we're going
1:37:18to say
1:37:19not executable and executable is another
1:37:22parameter you can specify and then we
1:37:24can use xrx here
1:37:26and we're going to say file and hit
1:37:28enter
1:37:29and you can see it tells us
1:37:31that maybe here07 and file2 has some
1:37:34ascii text with very long lines all
1:37:37right so let's cut the content off this
1:37:39file
1:37:40and just get it we're just going to
1:37:42enter here and we have the password so
1:37:44let's exit and go on to the final level
1:37:46in this particular video so i'm gonna
1:37:48go into level six hit enter
1:37:51and i'm gonna paste the password in here
1:37:53and we can now take a look at what level
1:37:56six pertains
1:37:58uh so level six the password for the
1:38:00next level is stored somewhere on the
1:38:02server and has all of the following
1:38:04properties so yeah this is now where we
1:38:06have the user and group specifications
1:38:09which is really simple so again we're
1:38:11told to look for a file
1:38:13on the entire server
1:38:15owned or the the entire linux file
1:38:17system that is owned by the user bandit
1:38:19seven
1:38:20and is owned by the group bandit six and
1:38:23in 33 bytes in size all right so we can
1:38:27then say um
1:38:28it's on the entire server we have any
1:38:30files here no we don't so we can say
1:38:32find and we're looking for a user which
1:38:36is going to be bandit seven and a group
1:38:39which is again very easy to specify
1:38:41group is going to be bandit 6
1:38:46the particular file we're looking for is
1:38:48going to be
1:38:5033 bytes so 33c
1:38:54[Music]
1:38:55i think that's pretty much it in regards
1:38:57to the options or the parameters that we
1:38:59were given so let's actually see if we
1:39:01can find this file when it enter
1:39:05and
1:39:05we get various
1:39:07you know permission denied errors here
1:39:10and it looks like we get a password file
1:39:13here so that's under the var folder or
1:39:15the var directory and it's a bandit 7
1:39:18password so let's copy the directory do
1:39:19that the actual file path the relative
1:39:22file path and cat the contents of that
1:39:24and we get the password to the next
1:39:26level and i'm just going to hit exit and
1:39:29we can move on to bandit level 7 which
1:39:32is now
1:39:32is is going to pertain to another
1:39:34challenge which is out of the scope of
1:39:36this video so
1:39:40in this video i'm going to be talking
1:39:41about shells now this might be a little
1:39:43bit confusing for you if you're a
1:39:45beginner to linux but um
1:39:47you the only thing you need to
1:39:49understand is that your the various
1:39:51types of shields you can use on linux
1:39:53now if you're using ubuntu or debian the
1:39:56default shell that you'll be you'll be
1:39:58given is going to be called the bash
1:40:00shell all right and again i can confirm
1:40:03this by echoing my variable my shell
1:40:05variable here so i can say echo shell
1:40:07and again it tells you the the current
1:40:09shell that i'm using which is bash now
1:40:11bash is an acronym for the born again
1:40:14shell
1:40:15uh so that means that there was a born
1:40:17shell and you're familiar with it and
1:40:19that is the sh or the sh shell so uh
1:40:23all of these shells can be used to to
1:40:26actually work with the linux system
1:40:28that's that's entirely up to you my
1:40:30objective in this video is to explain
1:40:33how to change your default shell and not
1:40:35work with the bash shell
1:40:37all right now
1:40:38on linux if you want to actually display
1:40:40all the shelves that you currently have
1:40:42that can be used uh you can essentially
1:40:45just read the contents
1:40:47of the shells file in the etsy directory
1:40:49and i can hit enter and you can see it's
1:40:52going to tell me it's going to tell you
1:40:53the valid login shells you have
1:40:55so we have the born shell which is the
1:40:58sh we have the born again shell which is
1:41:00bash which is the preferred
1:41:02shell to use you then have our bash and
1:41:04dash which is pretty good and then you
1:41:06have fish now i just installed fish and
1:41:09again many of you have been asking me to
1:41:11cover this i'll explain it after i've
1:41:13after actually explained passion how to
1:41:15use it how to customize it and stuff
1:41:17like that so for the purpose of this
1:41:19video i'm going to be using i'm going to
1:41:21be using bash and i'll later on cover
1:41:23the other the other shelves that you can
1:41:24use and you know using fish
1:41:27so the first thing is how to switch from
1:41:30shell to shell within a given terminal
1:41:32instance
1:41:33so i'm currently using the bash shell if
1:41:36i wanted to switch into the bond shell i
1:41:38can just hit sh and hit enter and you
1:41:41can see i'm now in the bond shell and
1:41:42again all the linux commands work
1:41:44perfectly fine i can hit all the various
1:41:46linux commands that i could run so i can
1:41:49list all the files in here etc etc you
1:41:51get the idea right so i can then say cat
1:41:54etsy shelves and again we can take a
1:41:57look at the shelves we have i can now go
1:41:59back into bash
1:42:00i can go into dash if i want to and
1:42:02again that takes me to in into into dash
1:42:05you can say echo and we can again
1:42:08confirm this and hit enter and it tells
1:42:10us we're still in pin bash that is
1:42:12because we're currently within this
1:42:14instance but if i changed it as my
1:42:16default login shell which i'll show you
1:42:18in a second how to do so let me just go
1:42:20back into bash
1:42:21and we will actually let me just clear
1:42:24this out so there we all right so
1:42:26you can see how easy it is to switch
1:42:28between shells in a particular terminal
1:42:30instance now
1:42:32by default as a user account on a linux
1:42:34system
1:42:35uh a
1:42:36you will be specified a particular shell
1:42:39to use and that can be found in the
1:42:40password file so if i hit enter so let
1:42:42me just grab it and display my account
1:42:45you can see that the shell is specified
1:42:47here and i'll explain this when talking
1:42:48about users and groups you can see that
1:42:50uh the default login shell that i have
1:42:53been specified to use is the bash shell
1:42:57which is perfectly fine now the great
1:42:58thing about linux is when creating the
1:43:00user you can specify the shell that
1:43:02they're going to use however you can
1:43:04also change the shell of the user or the
1:43:06user can change the shell that they want
1:43:08to use when they log in or every time
1:43:10they log in and the way we do that is by
1:43:12using the change shell command or the
1:43:15change shell utility which is defined by
1:43:18chsh or that's an actual abbreviation of
1:43:21the command so i can type in what is
1:43:23chsh
1:43:24and i'm going to enter you can see it
1:43:26tells you this allows you to change the
1:43:28login shell
1:43:29all right so if i want to change uh the
1:43:32default login shell all i need to do is
1:43:34let me first display the shells that i
1:43:36have here one more time all i need to
1:43:38specify is their relative path all right
1:43:40so if i say chs8 it's going to ask me
1:43:42for the password of my user here when it
1:43:45enter and it's going to say changing the
1:43:46login shell for the user lexis enter new
1:43:49value or press enter for the default the
1:43:51default login shell for me is bash so if
1:43:54i wanted to change it to
1:43:56to fish for example i would say
1:43:58user
1:44:00sorry that is user
1:44:02bin and i say fish i'm going to enter
1:44:04and that changes it for me all right so
1:44:07what this means in essence if i type in
1:44:09cat hc password here
1:44:12what this means
1:44:13let me just display the results here you
1:44:15can see that it changes uh the default
1:44:17login shell so this means that uh when i
1:44:20log out and i log back in
1:44:22uh what's gonna happen is that i'm gonna
1:44:24be given the fish shell as my default
1:44:26shell instead of bash so if you're
1:44:28wondering what the fish shell is uh you
1:44:30can install it very easily by typing
1:44:32sudo apt install or apt-get install
1:44:35whatever you find is useful for you
1:44:38just hit enter and i already have it
1:44:40installed so that's how to install it so
1:44:42what is fish fish is a friendly as a
1:44:45friendly interactive show it's a great
1:44:47show for beginners extremely
1:44:48customizable and you can see once i
1:44:50typed in fish it allowed me to log in
1:44:52the great thing about fish is it allows
1:44:54allows me to actually it actually gives
1:44:57me predictions in regards to the
1:44:59commands that i might be interested in
1:45:00running we'll get to this in a second
1:45:01let me go into bash
1:45:03all right so that is how to change your
1:45:05default login shell
1:45:07all right so again i'm right now i'm
1:45:09currently set to use fish as the default
1:45:12shell when i log in every time
1:45:14but let's talk about bash because that's
1:45:16uh that that's the primary goal of this
1:45:18video because it's the most used shell
1:45:20and the one you'll be coming across
1:45:22mostly so in my current home directory
1:45:24so in the user lexis directory here i
1:45:27have various bash files bash
1:45:29configuration files uh within this
1:45:32directory so i'm just gonna grab them
1:45:34and i'll say bash and of course they're
1:45:36gonna be hidden
1:45:37so i'm just gonna hit enter and as you
1:45:38can see i have a bash aliases file which
1:45:41you're not going to have by default i
1:45:42created this and i created it to to
1:45:45prove a point and to actually
1:45:46demonstrate an example here we then have
1:45:48the bash history uh file which has uh
1:45:51all your history of all your commands
1:45:53and this is very different to your
1:45:55actual
1:45:56gnu history uh utility
1:45:59um
1:46:00you have bash log out and bash rc bash
1:46:02rc is your bash configuration file i'm
1:46:04not gonna cover how to configure it it's
1:46:06extremely straightforward and you can
1:46:08pretty much configure it directly uh by
1:46:10using the preferences tab right over
1:46:12here
1:46:13but we can take a look at it i just want
1:46:15to show you how it is so and if we take
1:46:17a look at it here through vim you can
1:46:20see that
1:46:21it essentially allows you to to
1:46:23configure set
1:46:25variables i change the color change the
1:46:27the size of the history of the history
1:46:29file um
1:46:31let's see what else you can actually do
1:46:34here so there you can you can change the
1:46:36color
1:46:38this is all to do with color and you can
1:46:40you can do a lot of other stuff with uh
1:46:42in regards to customizing how it appears
1:46:44and and how it works so for example if i
1:46:47wanted um if i wanted bash to actually
1:46:51run the fish shell instead of the bash
1:46:54shell every time i started up
1:46:56i started bash up i would type in fish
1:46:58right just at the bottom here and let me
1:47:01save this file now and if i open up a
1:47:03new terminal you can see immediately it
1:47:05opens up the fish shell
1:47:07so that's pretty cool but this isn't the
1:47:09correct way of doing it or the preferred
1:47:11way of doing it so i'll just get rid of
1:47:13this fish command here
1:47:15and i'll save the changes here all right
1:47:16so now that we've talked about um
1:47:20now that we've talked about the bash rc
1:47:22file let's talk about the bash history
1:47:25file which is very important all right
1:47:26so
1:47:27by default in linux you have the history
1:47:30command um which again let me just type
1:47:32it in the history command is essentially
1:47:35the new history library now the the
1:47:36history uh
1:47:38this essentially allows you to to
1:47:40actually check uh a lot it stores a
1:47:42history of all the commands you've run
1:47:45and uh you know you can clear your
1:47:46history very easily by typing in history
1:47:49c right and it's as simple as that but
1:47:52it's not to be mistaken or confused with
1:47:55bash history which is again uh
1:47:57is specific to the bash shell or the
1:48:00bone again shell
1:48:01so again this file will contain a list
1:48:04of all the commands that i've run and
1:48:06and i'll show you how to clear it so if
1:48:08i get the contents of the file
1:48:10uh you can see that it it has all of
1:48:13these commands that i've been running so
1:48:15far you know perfectly fine
1:48:17and if i wanted to clear it it's very
1:48:20easy i can just redirect the the
1:48:22contents of the so i can say dev
1:48:25null and then
1:48:27[Music]
1:48:28i can redirect the output into the
1:48:30actual bash history file they bash
1:48:33history here hit enter clear this out
1:48:36if i now try and catch the contents of
1:48:39the bash history file
1:48:41you can see it has nothing so i've been
1:48:43able to clear my bash history i think
1:48:44i've covered this in my one of the
1:48:46videos where i spoke about uh actually
1:48:49clearing your tracks on linux so this is
1:48:51a great way of doing that and of course
1:48:53you can then use the history command if
1:48:55you want to do that so that's to do with
1:48:57actually using the um
1:49:00with actually working with the actual
1:49:02bash history here now let me talk about
1:49:04the bash aliases file all right so the
1:49:06aliases file is very simple it allows
1:49:08you to specify aliases or command
1:49:10aliases that you'd like to use now you
1:49:12can just create a file within your home
1:49:14directory and just name it bash aliases
1:49:16so what i'll do is i'll actually just
1:49:18show you the contents of the file
1:49:21so i can just show it show it to you
1:49:22right over here so bash aliases hit
1:49:24enter and you can see i have two aliases
1:49:27i have alias update which runs the
1:49:29command sudo apt-get update and then i
1:49:31have upgrade which runs the command sudo
1:49:34apt-get upgrade so it's fairly simple to
1:49:36understand what happens so i can just
1:49:38type in update and that will update my
1:49:40packages and then i can type in upgrade
1:49:43and that will upgrade my packages
1:49:44instead of typing the commands over and
1:49:46over again so that is what
1:49:48you know the command aliases are and how
1:49:50to specify them so again it's very
1:49:52simple in regards to configuring it
1:49:57in this video i'm going to be showing
1:49:59you uh how to enumerate intermission in
1:50:01regards to your current disk usage and
1:50:03in information you know in regards to
1:50:05how much storage your system is
1:50:06consuming how much you have left the
1:50:08various disks attached to your system
1:50:10etc stuff like that
1:50:12all right so as i said in the previous
1:50:13videos in regards to enumerating you
1:50:15know information about your system it's
1:50:17very important to know uh the state of
1:50:20view system and that you know could
1:50:21include the current ram usage uh what
1:50:24you the temperature of your processes
1:50:26are you know so again it's very
1:50:27important to know as a system
1:50:28administrator or someone who is going to
1:50:30be you know using linux uh you know more
1:50:34and more every day uh how to enumerate
1:50:37information and useful information like
1:50:39your current disk usage
1:50:41and the various drives that you have
1:50:43installed on your system so let's talk
1:50:45about disk usage first which is quite
1:50:47important right because when working
1:50:49with the terminal you have no gui you
1:50:51know programs
1:50:53that can actually you know visualize
1:50:54this for you so it's very important that
1:50:56you understand how to do this extremely
1:50:58important so the tool we're going to be
1:51:00using is a tool called du right and
1:51:02again it's fairly straightforward what
1:51:04that means that means disk usage so i
1:51:07can just say what is what is du and i
1:51:09can hit enter and as you can see it
1:51:10tells you this allows you to estimate
1:51:12file space usage right
1:51:15now du is a very simple tool to use and
1:51:18you can take a look at the man pages or
1:51:19in regards to how how to use it
1:51:22um so let's actually just run a simple
1:51:25command within this current directory
1:51:26and i'll show you what i mean so if i if
1:51:28i hit du
1:51:30uh you can see that
1:51:32this is um there's something weird
1:51:34happening here right so it's displaying
1:51:37a lot of files and uh when i say that it
1:51:40really is displaying it's displaying all
1:51:43the sizes of all the files within this
1:51:45directory recursively all right now you
1:51:48might be saying well what does that mean
1:51:50exactly
1:51:51well it means that it's actually showing
1:51:53you the size of all the files within a
1:51:56current working directory all right
1:51:58that's essentially what it means now
1:51:59what current directory am i working in
1:52:01i'm working in my home directory so we
1:52:03need to make this a little bit more
1:52:05human readable and the way we do this is
1:52:07by typing du and then we specify some
1:52:10arguments the first thing we want to do
1:52:12is we want to summarize
1:52:14all of these results into a uh into a
1:52:16format that we can understand right so
1:52:19instead of displaying recursively all
1:52:21the files here show us the top level
1:52:23directories and the total sizes of those
1:52:26directories and then we can go
1:52:27recursively within those particular
1:52:29directories if we wanted to all right so
1:52:32the s command is going to summarize
1:52:34everything up and then we want to use
1:52:35the h command the human readable format
1:52:38within this current working directory
1:52:40and i'm going to hit enter
1:52:42and as you can see right over here tells
1:52:45you it gives you a beautiful list of all
1:52:47the directories you have in this
1:52:49particular directory and on the left
1:52:51hand side you have their sizes in human
1:52:53readable format which means they have uh
1:52:56they have that they have size uh they
1:52:59have uni their various units in
1:53:00megabytes and in gigabytes
1:53:02and you know so far the the only file
1:53:05that's crossed at the threshold of one
1:53:07gigabyte is my virtualbox folder so
1:53:09again you can use a tool like trep to if
1:53:12you're going through tons of files on a
1:53:14system i'm just using simple examples
1:53:16here so you know i can say grep and you
1:53:18know i can say one uh one gig and we can
1:53:21hit enter and again that can be used to
1:53:23enumerate all of these all of this type
1:53:25of information or i can just say g
1:53:28g would be much better and there you are
1:53:30so again that's how to use grep in
1:53:32conjunction with all of these commands
1:53:34so that's how to use the disk usage tool
1:53:36now again i can go on to my um let me
1:53:40just go uh
1:53:41actually let's let's just go into the
1:53:43linux file system itself and say sudo uh
1:53:46eush and we'll run the same command and
1:53:48again we can hit enter and again that
1:53:50starts to enumerate the sizes of all of
1:53:52these directories now mind you it has to
1:53:54go through all of these directories and
1:53:56the subdirectories uh directories
1:53:58recursively to get this size so again
1:54:01for some particular files
1:54:02you will not have the adequate
1:54:04permissions to actually access so again
1:54:06there you are it gives you uh all the
1:54:08information you're looking for here and
1:54:09we can you know we can grab it to we're
1:54:12looking for the the big g for a gigabyte
1:54:15so the home directory has quite a
1:54:17few files the media directory uh the
1:54:20snap swap file user var etc etc
1:54:24um so let's take a look at one command
1:54:26i'll just go back into my home directory
1:54:27and i'll say man eu and we'll hit enter
1:54:33let's look for one
1:54:35one more command that yes the c command
1:54:38which will produce a grand total which i
1:54:40wanted to explain so i can say to you
1:54:42shc and hit enter and again that gives
1:54:45you a total of um
1:54:48it gives you a total of all of these
1:54:49files
1:54:50uh it gives you a total of all of the
1:54:52files and directories in this current
1:54:54working directory all right so that's
1:54:55pretty much how to use the disk usage
1:54:57tool
1:54:58uh to analyze the current disk usage
1:55:00within a particular directory now let's
1:55:02talk about the df tool so i can type in
1:55:04what is the fn8 enter and this is going
1:55:07to report file system disk space usage
1:55:10so we were talking about disk usage in a
1:55:12particular directory right but now we
1:55:14want to know our disk usage in relation
1:55:17to the total amount available right so
1:55:19we want to know how much we've consumed
1:55:21uh
1:55:22in our current uh disk where we have our
1:55:24home directory or just on all our drives
1:55:27right and to do this we type in df so
1:55:29again let me just open up the man pages
1:55:31so df
1:55:33um you can go through all the other
1:55:35arguments you want and we'll just quit
1:55:38and we'll say df for example
1:55:40all right so
1:55:41that displays a lot of information here
1:55:44that we we really don't need
1:55:46we're pretty much looking for our our
1:55:48system disks uh only
1:55:50and uh we can sort of narrow this down
1:55:52first of all by typing in so we can say
1:55:54df h is going to be for human readable
1:55:57format so again we can say man df and we
1:55:59say grep
1:56:01we're looking for h
1:56:03like so
1:56:04and uh
1:56:05sorry let me just uh we're looking for h
1:56:08here
1:56:09so again h is for human readable format
1:56:12all right so we can then say dfh
1:56:15and we can pretty much hit enter all
1:56:18right and what this does now is it's
1:56:20going to display
1:56:21all of all of your drives for you here
1:56:24and you then have the various so for
1:56:26example storage device c is the current
1:56:28uh file uh the current drive that i have
1:56:31my system installed on so it gives you
1:56:33uh it sorts it out into the file system
1:56:35size and a human readable format so
1:56:37gigabyte megabyte etc uh the amount used
1:56:40the amount available the usage
1:56:42percentage and where it's mounted so
1:56:44uh you can see that dev sd storage
1:56:47device c1 is mounted is the actual linux
1:56:50file system directory i then have
1:56:52various other
1:56:54external right so let's say i just
1:56:56wanted to display the storage devices
1:56:58right so i can you then utilize the grep
1:57:01tool i can say
1:57:02uh i can say grip uh sd and hit enter
1:57:06and there we are so it tells me all
1:57:07right so um you have sd sdc one and sdd1
1:57:12so sdc1
1:57:14has a total space of 117 gigabytes um
1:57:18and again we can what we can do here is
1:57:20uh we yeah
1:57:22that's perfectly fine so you have the um
1:57:24you have the current usage percentage
1:57:26which is 16 percent uh the amount point
1:57:28and then for my external drive
1:57:30you can see uh this is the total amount
1:57:32available uh the amount used the amount
1:57:35remaining and the usage percentage and
1:57:38where it's mounted on which is the media
1:57:40because it's an external drive
1:57:42all right so
1:57:43that is essentially how to use the df
1:57:46tool now we can specify
1:57:48additional options to uh to to actually
1:57:51only display
1:57:52results that we're looking for in
1:57:53regards to um to actually file file
1:57:56system formats so if you're looking for
1:57:58xt for ntfs what we can do is we can say
1:58:02uh we can say df h t right so t will
1:58:05specify the the file system for format
1:58:08so again we can say xt4 and we hit enter
1:58:10and that's going to only it's going to
1:58:12it's only going to display linux file
1:58:14systems and i'm going to enter and you
1:58:15can see it tells us sdc1
1:58:17and it gives us all the relevant
1:58:19information regarding the the size used
1:58:22uh used uh data the amount available and
1:58:24the usage percentage which is currently
1:58:26at 16
1:58:27so again that is how to analyze your
1:58:29disks uh your disk usage on linux and uh
1:58:32how to you know actually deduce how much
1:58:35disk space you're using how much is left
1:58:37the usage amount of where your various
1:58:39disks are mounted on etc etc
1:58:45uh in this video going to be talking
1:58:46about creating archives so you know
1:58:48creating tar files dart or gzip files
1:58:51and then extracting them so just how to
1:58:53manage and maintain the various archives
1:58:55you will be creating now there are many
1:58:57reasons to create archives on linux of
1:58:58course one of the reasons is it saves
1:59:01space uh you can if you're taking
1:59:03backups of particular directories uh
1:59:05it's great to have an autumn an
1:59:07automated script to to actually automate
1:59:10the process of archiving the files uh
1:59:12that's something that you can take a
1:59:13look at with my shell scripting series
1:59:16uh the link to that will be in the
1:59:17description section if you're interested
1:59:19in learning some shell scripting
1:59:21uh but let's get started with this video
1:59:23so uh the tool we're gonna be using is
1:59:25the tar tool now tar is an archiving
1:59:27utility as you can see here and again if
1:59:30we if we take a look at the man pages
1:59:32for this particular tool uh it gives you
1:59:34the various options that you can use you
1:59:36know in regards to creating uh archives
1:59:38comparing them deleting them etc so
1:59:41there's a lot of stuff in here
1:59:42the purpose of this video is to show you
1:59:44uh or to and to explain to you how to
1:59:46create uh how to create archives uh how
1:59:49they differ in terms of the extension
1:59:51and of course how to extract the various
1:59:53archives that i
1:59:54that you'll come across
1:59:56all right so uh on my desktop what i've
1:59:59done is um i've created a simple
2:00:02directory here uh let me just uh remove
2:00:04this uh
2:00:06this directory right over here um there
2:00:09we are and um so i created a directory
2:00:12called file
2:00:13and within this directory uh you can see
2:00:16that i've created a
2:00:18a test.txt file that contains uh the
2:00:21contents of the password file so just a
2:00:23random file that you know you may want
2:00:25to uh you may want to archive or random
2:00:28directory that you you may want to
2:00:29archive so if i wanted to create a tar
2:00:32archive of this file directory what i
2:00:34would do is i would say tar and then i
2:00:36would specify
2:00:38you know some arguments here
2:00:40in in regards to what i want star to do
2:00:43so first of all i would want dart to
2:00:44compress the file
2:00:46um and then of course i want uh i wanted
2:00:49to compress
2:00:50this file so we're specifying the file
2:00:52um now after this we specify the name of
2:00:55the archive that we want to give it so
2:00:57we'll just call it file dot dar this is
2:01:00different than a dar.gz
2:01:02archive and i'll explain how that
2:01:04differs shortly so then we specify the
2:01:08the directory that we want to actually
2:01:10archive and we hit enter
2:01:12and there you are so you can see it
2:01:14created uh the tar file for us and of
2:01:16course if we type in um file and
2:01:19file.tar you can see it tells you that
2:01:21this is a tar archive gnut or archive
2:01:24here so that means it was it worked
2:01:26correctly now um
2:01:28let me remove this uh the star archive
2:01:30here and if we run the same command that
2:01:33we did
2:01:34sorry about that let me just um let me
2:01:36let's do it one more time so you can say
2:01:38tar
2:01:39we can also use the uh the v command and
2:01:42that will give us some verbose output in
2:01:44regards to what files are currently
2:01:46being processed uh you know in the
2:01:48overall archiving uh process so again we
2:01:51can say tar cvf
2:01:53and then we say dar we can just say
2:01:55file.um
2:01:58file.tar and then we specify the
2:02:00directory and we hit enter and you can
2:02:02see it then gives you a the post output
2:02:05and we get the dar the file.tar archive
2:02:07here so
2:02:09if we want to extract a tar archive
2:02:12that's a very very simple thing to do
2:02:14all we need to do is we say tar
2:02:17guitar
2:02:19and now that we want to extract it we
2:02:21use the x command uh by the way you can
2:02:23you can negate or not use the iphone
2:02:26here but i personally like using the
2:02:28iphone just so that i understand where
2:02:30my syntax is going so i can say extract
2:02:33and we can verbose you know we can have
2:02:35some verbose output
2:02:37and we say extract
2:02:39the file and then we specify the file so
2:02:42we say file.tar and then we can provide
2:02:46an output for it or you can just hit
2:02:47enter and it you know it extracts it for
2:02:50us and because we already have the file
2:02:52here uh it will essentially overwrite
2:02:54the
2:02:55uh the newer files if the if there are
2:02:57any new changes etc so we can uh
2:03:00we can remove this directory and do that
2:03:02one more time here so we can say star
2:03:06xvf
2:03:07file dot r and we hit enter now if we
2:03:10list this you can see that we have the
2:03:12file directory here all right excellent
2:03:15so that's uh working with star files and
2:03:17that's you know a standard tar
2:03:20a guitar file here uh now let's talk
2:03:22about gzip files so if i say what is
2:03:26gzip and uh you can do this with star
2:03:28again uh it's a very very simple you
2:03:31that's the preferred way of doing it so
2:03:33uh let's take the um
2:03:36the same or we can just remove the file
2:03:38dot our here so let's take the same
2:03:41file directory here and if we want to
2:03:44now use the or compress it
2:03:47into a third or gzip file
2:03:50using gzip of course then we would say
2:03:53tar
2:03:55uh now we are compressing it so we say c
2:03:57z uh f or c z c v z f or c z v f
2:04:02whatever you want to use in our case we
2:04:04we don't want to work or we want to
2:04:06display uh you know some the verbose
2:04:09output so we can just use the czf
2:04:12and then we specify um
2:04:14we specify the name so we're going to
2:04:16say file.tar
2:04:18register and then we specify the
2:04:20directory that we want to archive or
2:04:22compress and we hit enter
2:04:24and you can now see that we created the
2:04:27gz file here so if we type in file and
2:04:29then you know just to find out what
2:04:31we're dealing with the ui tells you
2:04:33we're dealing with a gzip compressed
2:04:35data
2:04:37so again we can extract it really simply
2:04:39by saying dar
2:04:41um dar x z f
2:04:44x z f and then we say file
2:04:46dot r g z but uh before we do this uh
2:04:49let's remove uh let's remove the actual
2:04:54file directory here so we say term
2:04:57x zf and then we say
2:04:59file.gz and we hit enter and it'll then
2:05:03give us the file directory which is
2:05:05right over here so again we can cut the
2:05:06contents just to show you that it's
2:05:08worked just fine
2:05:10um
2:05:11you can see that it's the entire content
2:05:13of the password file so that's pretty
2:05:15much how to work with archives i'm not
2:05:17going to be covering the various other
2:05:18utilities that you can use so for
2:05:20example bc2 which is again very simple
2:05:23use uh in regards to using bzip2 for
2:05:26compression i wanted to show you how to
2:05:28use the tar uh guitar utility for
2:05:31archiving files archiving them and then
2:05:33of course extracting them so it's the
2:05:34most reliable and consistent way of
2:05:37working with archives on linux and it's
2:05:39great for you know taking backups and
2:05:41with the help of a shell script you can
2:05:43easily automate the process
2:05:48in this video i'm going to be talking
2:05:50about uh you know adding managing users
2:05:52and groups and then in the follow up
2:05:54videos we'll be talking about user
2:05:56security and sort of securing the
2:05:58authentication uh section or area of of
2:06:01linux so let's get started now i just
2:06:03want to give you a bit of a premise
2:06:05i'm currently running a um currently
2:06:07logged in by ssh onto one of my uh linux
2:06:10servers and the reason being is as we
2:06:12move on into this series to to the end
2:06:14or to the completion uh i'll be covering
2:06:16security uh you know various security
2:06:19aspects that we will require a lot of
2:06:20testing so again uh that's primarily the
2:06:22reason so let's get started now by
2:06:24default
2:06:25uh you can see that i've created another
2:06:27user called admin
2:06:29and i'm currently running ubuntu server
2:06:31so
2:06:32what's going to happen is uh it is
2:06:34recommended never to only be using the
2:06:36root user and that you need to have
2:06:38another user in which you can then uh
2:06:40start you know applying various
2:06:42permissions to so by default on ubuntu
2:06:45uh when working with users again is a
2:06:48very very simple syntax in regards to
2:06:50adding them so what we're going to do is
2:06:51we're just going to create a user here
2:06:53we're just going to say user add and you
2:06:55can take a look at all the uh the
2:06:57various options you can use when
2:06:59specifying a user
2:07:00so if i just say uh user add and i hit
2:07:04enter you can see it doesn't give me any
2:07:06prompt but if i say user add alexis and
2:07:09i hit enter it will give me
2:07:11an error with the um
2:07:13it will give me an error with with a
2:07:15lack of permissions now i did this uh
2:07:17you know deliberately so that i can
2:07:19demonstrate uh how to use groups before
2:07:21we actually take a look at that so i'll
2:07:23just switch i'll just switch into the
2:07:25root user here
2:07:26and we'll go into my home directory and
2:07:28we'll just say v sudo here uh so we'll
2:07:31say v sudo and
2:07:33what we want to do now
2:07:35is we have the user admin uh but we want
2:07:38to
2:07:39we want to actually have this user
2:07:42[Music]
2:07:43we want to add this user admin into the
2:07:45sudo group which will essentially allow
2:07:48members of the group to execute any
2:07:49command now i can do that or i can also
2:07:51add them to the admin to the admin group
2:07:54which which would be better
2:07:56um so again we can sort of customize the
2:07:59various uh the various commands that we
2:08:01can specify and i'll get to this in a
2:08:02second so
2:08:03uh what we want to do now is i'll just
2:08:06exit and i'll say user mod
2:08:08and i'll say user mod a
2:08:11g
2:08:12ad group and then we say
2:08:14admin and the user admin and we hit
2:08:17enter and that's going to add the user
2:08:19admin into the group admin so you
2:08:21specify the group first and then the
2:08:22user there that might might seem a bit
2:08:25confusing but if i just say groups uh
2:08:27groups admin you can see that it tells
2:08:30me that the user admin is in the group
2:08:32admin all right so if we go back into
2:08:33the user admin here
2:08:35you can see it tells you to run a
2:08:36command as administrator use
2:08:39user root use the sudo command so again
2:08:41we now have permissions to do whatever
2:08:42we want so if we go back here
2:08:45we can say sudo user add
2:08:48user add and
2:08:49again that will give us the same option
2:08:51so if we say user ad alexis
2:08:53uh it's going to add the user now the
2:08:55problem with this if i display the
2:08:57password file
2:08:58you can see that the user alexis by
2:09:00default will be given a home directory
2:09:02that's perfectly fine and the diff the
2:09:04default shell will be set to the bond
2:09:06shell so what i want to do is let me
2:09:08show you how to remove a user so to
2:09:10remove a user we say user dell and then
2:09:12if we want to remove their home
2:09:13directory
2:09:14we say uh r or we use the recursive
2:09:17command and then we specify the user so
2:09:19we can say alexis
2:09:20and again we need to use um
2:09:24the
2:09:24we need to use the sudo command here
2:09:26because we require root privileges so
2:09:28it's going to remove
2:09:31it's going to remove the user so if we
2:09:32just display the
2:09:34uh the contents of the home directory we
2:09:36can see that the only user directories
2:09:37we have are for the user admin all right
2:09:39so now that i've explained that let me
2:09:40show you the correct syntax for adding a
2:09:43user here so again i can just say user
2:09:45ad now
2:09:47uh in regards to the actual commands you
2:09:49can use you can take a look at the man
2:09:51pages uh sorry um
2:09:53user ad and you can take a look at all
2:09:56of these options and there's a quite
2:09:58extensive options you can use in regards
2:10:00to creating user but in our case we want
2:10:03to say user ad and um
2:10:05the first thing we want to do is we want
2:10:07to make sure that this user has a home
2:10:09directory with its username appended so
2:10:12we can say m
2:10:13and then we can add a comment so again
2:10:15this can describe uh you know something
2:10:17about the account and what it's used for
2:10:19we can just say alexis and we can then
2:10:21specify the shell this is very important
2:10:23if you want a uh
2:10:25if you want the user account to to use a
2:10:27custom shell
2:10:29in our case we'll just say bin bash and
2:10:31then we specify the name of the user
2:10:33account or the username and we hit enter
2:10:35all right so again it tells us we need
2:10:36sudo privileges so let's add that and
2:10:39i'll just hit enter and the the user is
2:10:41added now this user doesn't have a
2:10:43password yet so to add a password for a
2:10:46user we can say we can use the password
2:10:48command all right and again it requires
2:10:50root
2:10:50privileges
2:10:52so if i wanted to change the password
2:10:54for the admin account or for the current
2:10:56account that i'm using i simply type in
2:10:57password and it'll say changing password
2:11:00for admin and it'll ask me for my
2:11:01current password
2:11:02i'll enter a new password here
2:11:05and the password isn't changed so i just
2:11:07wanted to demonstrate this so again i
2:11:09can just say let me just change the
2:11:11password here
2:11:12and i'll just change it to something
2:11:15different and there we are so the
2:11:16password for the admin user has been
2:11:18updated successfully
2:11:20if i wanted to change the password for
2:11:22another user i would say password alexis
2:11:24and hit enter
2:11:26so again we we can use the sudo
2:11:28privileges because we're now modifying
2:11:34and
2:11:36sorry about this let's just add um
2:11:40and there we are so now we've added the
2:11:42password for the user lexis so i can
2:11:44directly switch uh into this user
2:11:47account and i'll show you something
2:11:49interesting here so i can say sudo
2:11:51alexis
2:11:52um and i switch into it and um
2:11:56there we are so now if i try and do
2:11:57something like sudo apt update here
2:12:00uh it'll ask me for the user for the
2:12:02password and um well i think i entered
2:12:04the correct the incorrect password here
2:12:06so if i enter the correct password you
2:12:08can see it's going to tell us that
2:12:09alexis is not in the sudoes file this
2:12:11incident will be reported all right so
2:12:14that's um that's essentially telling us
2:12:16we don't have adequate adequate
2:12:18permission so if we go back into the
2:12:19admin account
2:12:20um
2:12:22we can now play around with the sudoers
2:12:25file so again we'll say sudo vsudo and
2:12:28we'll hit enter and let's talk about now
2:12:30adding permissions and before we
2:12:32actually take a look at groups
2:12:34right so typically with ubuntu uh you
2:12:37can see that it gives you all of these
2:12:38various groups you know right out of the
2:12:40bat and you you can specify specific
2:12:43user privileges
2:12:45under this right over here so you can
2:12:46see for the root user um
2:12:49it can run it from all uh sessions
2:12:51irregardless of whether it's a tty uh or
2:12:54a remote session
2:12:55uh and then you know for all users in
2:12:58all groups and it can run all commands
2:12:59so again again just say alexis and let's
2:13:02say all or you know i can just simply
2:13:04say
2:13:05uh all sorry that's always going to be
2:13:07equal to all and so that's pretty much
2:13:10uh all users um
2:13:13and then in regards to the command
2:13:15specification which you specify here so
2:13:17this user can actually run all
2:13:20permissions or i can limit it to you
2:13:22know certain permissions if i want to
2:13:24right now again
2:13:26this will pretty much
2:13:29this this will pretty much allow me to
2:13:32to actually run uh specific commands so
2:13:35for example if i wanted to only allow
2:13:37this user to say for example user bin
2:13:40apt
2:13:41get
2:13:42for example um so what i'll do is i'll
2:13:44just save this file and we'll go back
2:13:46into the user lexis here
2:13:48um and we'll say
2:13:51and then we say sudo apt get and many of
2:13:54you might be catching on and you'll see
2:13:56what happens here
2:13:58so you can see that that works now and
2:14:01we're able to run only that command with
2:14:02root privileges
2:14:04so we'll just wait for this to actually
2:14:06update the repositories
2:14:08let's try and run another command with
2:14:10root privileges and i'll show you what
2:14:11will happen here so
2:14:13again my apologies my internet is
2:14:16really not that quick um so we'll just
2:14:18wait for this to complete
2:14:21and um
2:14:22so there we are
2:14:23got the repos and you know i can pretty
2:14:25much install software and i can use the
2:14:28app to get a utility so if i say sudo
2:14:31um let's say vim
2:14:33hc
2:14:34ssh sshd config if we open this you can
2:14:38see we're not allowed to do this so if
2:14:40we go back into the admin user
2:14:42you can see now this is a great way of
2:14:45you know specifying um specifying
2:14:48permissions for users so
2:14:50additionally what i can do is i can use
2:14:52groups right now
2:14:54i have the user alexis here and let me
2:14:56just comment this if i say all commands
2:14:59uh that means it can run all commands
2:15:01here without any uh without any
2:15:03restrictions so we then have groups
2:15:05right now groups
2:15:06allow
2:15:08groups essentially allow users to allows
2:15:10you to group users you know based on
2:15:12their particular role or
2:15:14responsibilities now in this case we
2:15:15have two groups we have admin and sudo
2:15:18and they essentially allow users to
2:15:19execute all commands with root
2:15:21privileges here
2:15:23um so
2:15:24uh what we can do is uh we can create
2:15:27another group here so uh
2:15:30we can just exit out of this uh well
2:15:32actually no
2:15:33we can just modify this one more time
2:15:36because uh i want to actually comment
2:15:38this in regards to the permissions here
2:15:40so we'll just exit and let's talk about
2:15:42groups all right so let's talk about
2:15:44groups in linux now groups are a great
2:15:47way of sort of collectively applying
2:15:49permissions to you know groups of users
2:15:52that you know you may want to have uh
2:15:54you know the same privileges uh or
2:15:57permissions uh and you know it's a great
2:15:59way of
2:16:00blanketing
2:16:01various permissions on different users
2:16:03and a great way of of course segregating
2:16:05roles and duties within a system so it's
2:16:08a great way of actually actively
2:16:11uh
2:16:12actively approaching uh the whole idea
2:16:15of segregation of roles and duties so
2:16:18let's talk about uh creating groups uh
2:16:20deleting groups and of course working
2:16:22with permissions with groups so we're
2:16:24going to follow this the same scenario
2:16:26we have the admin user uh and of course
2:16:29we then have the user alexis here so the
2:16:31user lexis currently is not part of any
2:16:34any any particular group so again it's a
2:16:36standard user account that doesn't have
2:16:38root privileges and is simply just
2:16:40allowed to operate within those
2:16:42constraints now if i wanted to add a
2:16:44group here i would say group add right
2:16:47and then i'll specify the name of the
2:16:48group so let's say we want to add the
2:16:51the user alexis to a group called
2:16:54developers
2:16:55right so we're going to say group add
2:16:57developers let me just prepend this with
2:16:59sudo because we do need root privileges
2:17:02to create new groups and we're going to
2:17:03hit enter all right so now we have the
2:17:06group created so if we want to display
2:17:08groups for a particular user or the
2:17:10groups that a user is in again we use
2:17:12groups and then the name of the user
2:17:15and you it tells you that alexis
2:17:16currently is is in its own group we can
2:17:19view all the groups on the system by
2:17:21visiting the or cutting or displaying
2:17:24the contents of the group a file if we
2:17:27hit enter you can see that we have the
2:17:29various groups and you can see we have
2:17:31all the system accounts as well as
2:17:33pretty much they're going to be in their
2:17:34own group unless
2:17:36uh specified otherwise
2:17:40um so let's uh let what we're gonna do
2:17:43is we're going to add the user alexis
2:17:46into this developers group and then i'll
2:17:47show you how permissions can sort of be
2:17:50uh be manipulated that way so we're
2:17:52gonna say user mod and we're gonna say
2:17:54we're gonna append append
2:17:56the user lexis and we're going to say
2:17:58the group by the way you can use a
2:18:00lowercase g here the lowercase g
2:18:02primarily means you need to specify the
2:18:04group ids in our case we'll just use the
2:18:07capital g because we know the names of
2:18:09head
2:18:10so we'll say developers and we want to
2:18:12add the user alexis to the group
2:18:14developers
2:18:16i believe we need root privileges for
2:18:18this so i'm going to enter and that
2:18:20should do it all right so now if i say
2:18:21groups alexis you can see that alex is
2:18:24going to be part of its own group and
2:18:26uh
2:18:27and the developers group now when we
2:18:29talk about having its own group that
2:18:31simply refers to you know user specific
2:18:33privilege specifications so again if we
2:18:35visit the uh the v sudo uh utility uh to
2:18:39modify the sudoes file
2:18:42you can see that we talked about user
2:18:44user privilege specification and we had
2:18:46actually added a uh you know some
2:18:49privileged specifications for the user
2:18:52alexis where
2:18:54you know we can access it from all hosts
2:18:56and we've specified all users however
2:18:58not all groups so this essentially will
2:19:01restrict
2:19:03uh this will restrict
2:19:05the user alexis uh
2:19:07and it will essentially allow him to run
2:19:09uh you know the apt-get utility with
2:19:12root privileges here
2:19:14however
2:19:16that's one way of doing it so if if i
2:19:18use this if i use this this same syntax
2:19:22uh then i can also you know allow it to
2:19:24run all commands
2:19:26and you know i can also specify the uh
2:19:28the exp explicitly to refuse
2:19:32to refuse it to use the root uh to
2:19:35actually have pseudo privileges so it
2:19:37will only run this command
2:19:39uh and and you know so on and so forth
2:19:41so i can do that actively if i wanted to
2:19:43however i don't want to so what we'll do
2:19:45is let's just test this out to see that
2:19:47it works and of course you can change
2:19:49this to whatever
2:19:50whatever command that will require you
2:19:52know root privileges so we can just use
2:19:54app to get here and i'll save this now v
2:19:57sudo when saving and exec
2:19:59and exiting if you do have a syntax
2:20:01error it will tell you so again if we go
2:20:03here and we say
2:20:05let's uh let let's actually mess around
2:20:07with the syntax here so again i can just
2:20:09say add a few uh commas there you can
2:20:13see that it tells us uh in the etsy
2:20:15pseudo as well as syntax error near line
2:20:1721 and we can use the e command to edit
2:20:20it so again that's a great uh that's the
2:20:22great uh reason for using these the uh
2:20:26the v sudo utility it actually points
2:20:28out logical and uh and syntax errors
2:20:32so we'll save this now and we'll exit
2:20:35and what we'll do is we'll now switch
2:20:37into the user lexis and um
2:20:40i'll go here and you can see that now if
2:20:42i type in apt-get update you can see
2:20:44that we can run this command but it
2:20:46still requires administrative privileges
2:20:48or root privileges so if we pre-pend it
2:20:51with root or sorry sudo
2:20:54if we say sudo and we hit up and we just
2:20:56enter the password you can see that
2:20:58we're able to run the command however if
2:21:01we wanted to display the um we say cat
2:21:04etsy shadow
2:21:06uh
2:21:08cat etsy shadow is going to tell you
2:21:10these alexis is not allowed to execute
2:21:12cat etsy shadow with you know root
2:21:15privileges so again we can say cat
2:21:17hc password here that works because it
2:21:20doesn't require root privileges and we
2:21:22are pretty much allowed to view the
2:21:24contents of this file
2:21:26all right so that's how to apply
2:21:27permissions based on a user all right
2:21:30now i can also change this up and we can
2:21:32use the the example of the group here so
2:21:35we can just go back into the user admin
2:21:38and
2:21:38just enter the password here and again
2:21:40we'll say sudo
2:21:42vsudo and we'll get into this so we'll
2:21:45comment this uh you know user privilege
2:21:47specification entry and we can enter our
2:21:49group anywhere here we can just add a
2:21:51comment if we wanted to
2:21:56specification
2:21:58um developer group
2:22:00we can just say developer group and then
2:22:02we say
2:22:03when adding a group we prepend it with
2:22:05the the modulus sign and then we say we
2:22:09specify the name of the group so we say
2:22:11developers and then after this we
2:22:13specify the permissions here so again we
2:22:15can say all
2:22:16all hosts and then we'll say all users
2:22:20of all groups that's because we need a
2:22:23sudo that's very important we need the
2:22:26ability to access all the groups so
2:22:28again we can all we can always limit it
2:22:30to
2:22:31uh all users and then the admin group if
2:22:34we wanted to but again we say all
2:22:38and then instead of all commands we say
2:22:40user bin
2:22:43we can say apt user pin
2:22:46sorry user bin apt get update uh sorry
2:22:49apt-get sorry not update
2:22:52um so we can save this and if we exit
2:22:54you can see we have no syntax errors so
2:22:56again back to alexis here
2:22:59and i will enter the password
2:23:01and uh yeah so now we can say sudo apt
2:23:05uh
2:23:06get update and that works fine uh for
2:23:09some reason
2:23:11uh not allowed to execute uh let me just
2:23:14check this right now uh yeah it's part
2:23:16of the developers group uh let me just
2:23:19go back into the admin group here oh
2:23:21sorry into the admin user
2:23:23and uh let's see what the issue is
2:23:26what's the issue is with the
2:23:27specification of uh
2:23:30of permissions here um
2:23:33so
2:23:35what i'll do is um let's see what can be
2:23:39this shouldn't be causing any issues uh
2:23:42let's try apt and let's just see whether
2:23:44this works i'll just say
2:23:54i have to update that that works fine
2:23:57um i believe you need to add yeah you
2:23:59need to separate the commands and it
2:24:02would be wise to use command command
2:24:04aliases so yeah i i simply forgot about
2:24:06that sorry about that guys um so so that
2:24:08will work fine so again if we say sudo
2:24:11cat etsy shadow
2:24:13for example
2:24:14yeah because we wanted to view it you
2:24:16can see it again it restricts us to
2:24:18running uh only the apt update utility
2:24:20or running the app utility here so that
2:24:23is how to you know sort of segregate
2:24:25permissions based on a user whether you
2:24:26want to specify the permissions you know
2:24:28on a user to use a basis
2:24:30or how to specify the permissions on a
2:24:32you know in in regards to adding users
2:24:35to a group and then applying them that
2:24:36way sort of blanketing the users that
2:24:39way so again it's all about
2:24:41you know what philosophy you are you
2:24:42adapt to and if you're a system
2:24:44administrator it'll also depend on the
2:24:46use case and the use you usage scenario
2:24:49in which your server is being deployed
2:24:52in
2:24:56we're going to be talking about
2:24:57networking uh in the command line all
2:24:59right so let's get started now
2:25:01um if you pretty much watched any of my
2:25:04older videos where we were working with
2:25:06networking within the linux terminal you
2:25:08know that i would typically use the
2:25:10ifconfig utility however
2:25:13you know the standard has changed now
2:25:15and what we have to use or what is the
2:25:17preferred method of getting information
2:25:20and interacting with various network
2:25:22interfaces is by using the ip command
2:25:24right so the ip
2:25:26utility allows you to you know show
2:25:28manipulate routing network devices
2:25:30interfaces and tunnels etc
2:25:32all right so let's get started by first
2:25:35of all um understanding how to display
2:25:37your current uh routing table so again
2:25:39we can do that by typing in ip route
2:25:42show and that's very simple so ip route
2:25:44show and this will show you your current
2:25:46uh routing table so you can see this is
2:25:48my uh this is uh this is currently my
2:25:51router's ip address or my gateway uh
2:25:53this is my interface name here and this
2:25:56is the source ip which is my ip address
2:25:58so that gives you an idea of uh of your
2:26:00ip routing table uh currently
2:26:03now again you can take a look at uh we
2:26:06can grip route here and uh in the man
2:26:09pages and you can take a look at all the
2:26:10options you have available for you um so
2:26:13you can pretty much change the route if
2:26:15you want to do but of course that's
2:26:16beyond the scope of this tutorial i'm
2:26:18simply showing you how to find
2:26:20information that's very useful if you
2:26:21want to display your current ip address
2:26:23we type in
2:26:25ipaddr and we hit enter and this gives
2:26:28you your two interfaces so we have local
2:26:31this is a loop back so this is you know
2:26:33for your local host
2:26:35uh and you then have your ethernet in my
2:26:37case my ethernet adapter which has the
2:26:39interface name enp2so
2:26:42you can see that it has an ip of
2:26:45192.168.1.1
2:26:48and you have the uh the entire uh
2:26:51the entire network range there
2:26:53um you also have your your ipv6 ip
2:26:56address here that is required and of
2:26:58course you have your mac address so very
2:27:00similar to ifconfig um so if we
2:27:03if we take a look at ifconfig which is a
2:27:06perfectly great uh tool that you can use
2:27:08and so you know you can use it if i type
2:27:10in i have config
2:27:12we can take a look at the man pages here
2:27:14just so i can show you the flexibility
2:27:16so again uh you can play around with all
2:27:18the options that are available but
2:27:20pretty much the simple way of going
2:27:22about it would be to simply display your
2:27:24current um so if i say ifconfig
2:27:28and i'm only looking for my
2:27:30i can say inets if i'm only looking for
2:27:32my ipv4 address or my inet addresses you
2:27:35can see that i can easily just print
2:27:37them out and i also have my net mask so
2:27:39a very organized way of taking a look at
2:27:42your your interfaces and your ip
2:27:44addresses as well
2:27:46right now i'm still to make a video on
2:27:48on managing services
2:27:51and processes with linux but uh
2:27:53essentially working with your network
2:27:55manager we can also take a look at dhcp
2:27:58because that would be quite important so
2:28:00if you are running this on wi-fi or you
2:28:02are using a wireless adapter or even an
2:28:04ethernet where you don't have static ip
2:28:08distribution
2:28:10or resolution what we can do is if we
2:28:12say what is dhclient um and we can just
2:28:15hit enter you can see that uh if we type
2:28:17in dh client and we hit enter you can
2:28:19see that it doesn't give us any
2:28:22any options here so if we take a look at
2:28:23the options that we available to use we
2:28:26can pretty much um
2:28:28let's take a look at the man pages
2:28:29because this is a bit better way of
2:28:32actually utilizing it so again we can
2:28:34use the dhcp v4 protocol to obtain
2:28:38a new ipv4 address but in my case i i
2:28:41have my ip statically uh assigned here
2:28:43so that would not be a wise thing to do
2:28:46but if i wanted to restart my network
2:28:47manager uh again i'll be making a an
2:28:50individual video on this so you don't
2:28:52have to worry so you can use sudo
2:28:53service
2:28:54network
2:28:57network manager
2:28:58um
2:29:00restart and i can hit enter or i can use
2:29:02system d so i can say sudo system
2:29:05control
2:29:06uh we can say restart we say network
2:29:09let me just see network we're looking
2:29:11for the network manager here so if i let
2:29:13me just tab and see what we have we're
2:29:16looking for the network manager.service
2:29:18which is right over here so i can
2:29:20execute this and that will essentially
2:29:21restart it now again as i said if you're
2:29:23not familiar with processes don't worry
2:29:25we'll be covering it in the next set of
2:29:27videos as we wind up this series
2:29:29but that's pretty much how to restart
2:29:32your network adapter if you're having
2:29:33any issues and you can sort of work with
2:29:35that now let's talk about netstat
2:29:38because again that's quite an important
2:29:40tool and i haven't i have a an
2:29:42independent video on how to use netstat
2:29:44if you are interested in it so again we
2:29:46can say netstat and we hit enter say
2:29:49print network connections routing tables
2:29:51uh et cetera et cetera so i'll just go
2:29:53i'll just go over the most common
2:29:55options you can use and this essentially
2:29:56allows you to understand what uh what
2:29:59services ports uh you have running
2:30:01listening and are you are connected to
2:30:03so for example
2:30:04if i wanted to display the route i would
2:30:06say net stat and i would say r and that
2:30:09gives me my routing table so we have the
2:30:11destination uh the gateway the gen mask
2:30:14flags and the interface here
2:30:17so in all cases we're working with my uh
2:30:18with my ethernet interface here so you
2:30:21can see that
2:30:23for the default gateway uh we have it
2:30:25right over here the destination and of
2:30:27course the gen mask so again you can get
2:30:29very good information from this now if
2:30:31we wanted to take a look at all the tcp
2:30:33connections that we have we can say net
2:30:36stat and we use t and that gives us all
2:30:39the tcp connections on uh that we are
2:30:41currently connected to or listening
2:30:43for on our system so you can see that uh
2:30:47we have the protocol which is very
2:30:48important this is this is uh uniquely
2:30:51going to be tcp
2:30:52uh the local address the foreign address
2:30:54the port it gives you and the state
2:30:56which i'll get to in a second
2:30:58um so you can pretty you can also grab
2:31:00information from this so again you can
2:31:02say grip and if i had the ssh
2:31:04uh port open uh i would hit i'll say
2:31:07grep 22 for example and uh you pretty
2:31:10much gives you results based on
2:31:12the actual string of characters in this
2:31:14case it's not giving us anything new but
2:31:16if all to say
2:31:17um let's say
2:31:19sudo
2:31:21sudo
2:31:22service ssh
2:31:24start now hit enter
2:31:27and if we try and grip this now uh we
2:31:29don't get anything so let's uh let's
2:31:31take a look at how to find a listening
2:31:33ports so or listening socket so we can
2:31:36say netstat
2:31:38l and we hit enter and you can see
2:31:40there's quite a bit of listening uh of
2:31:42stock of sockets that are currently
2:31:44listening for
2:31:46uh
2:31:46for actual connection so in our case you
2:31:49can see we have the ssh port here
2:31:51and we can pretty much grip
2:31:54with these particular services um and
2:31:56you can sort of work with that if you
2:31:58want to
2:31:59uh talking about udp only we can again
2:32:02that's very simple so that's that if i
2:32:04wanted listening tcp connections i would
2:32:07say um for example lt and hit enter and
2:32:10that will only display the listening tcp
2:32:12connections if i wanted listening udp
2:32:14connections i would
2:32:16type in lu and again that gives us all
2:32:18the listening udp connections
2:32:21um if we want to display the the actual
2:32:24processor processes and the process ids
2:32:27we can say netstat
2:32:29p and we hit enter
2:32:31and what we can do is we can say ltp
2:32:34so ltp and we're looking for grip ssh
2:32:38and we hit enter it again tells you uh
2:32:40that we have ssh running in or you can
2:32:42go through this all over again so let me
2:32:44just clear this out
2:32:46so if we display the results here um you
2:32:48can see that
2:32:50it gives you all the information that
2:32:52you're looking for uh so if we get rid
2:32:55of this and we also have p it gives you
2:32:57the various process ids
2:32:59uh so if we let's just take a look at
2:33:01the table right at the top here that
2:33:03pretty much prints it all
2:33:05uh you can see we have the pid right
2:33:07over here and we can sort of grip
2:33:09through that if we wanted to
2:33:12so that's uh using um netdiscover
2:33:15netstat uh we're not talking about net
2:33:17discover yet but again you can check out
2:33:19our independent video on that and allows
2:33:22you to check various connections that
2:33:23you have open and you know running
2:33:25either established or listening on your
2:33:27system they could be for both a tcp and
2:33:29udp
2:33:30now let's talk about net discover now
2:33:33net discover does not come pre-installed
2:33:35with any linux distribution as far as
2:33:37i'm concerned apart from the pen testing
2:33:39uh or offensive distribution so again we
2:33:42can simply just say what is netstat
2:33:45and you can pretty much um well no not
2:33:47nets that net discover
2:33:51um i believe this is uh its cover like
2:33:54so and we hit enter and it's an active
2:33:56passive uh erp reconnaissance tool
2:34:00and so what this means is it allows you
2:34:02to essentially scan your network for uh
2:34:04for other devices or hosts that are
2:34:06currently connected to your network
2:34:08whether they be uh wi-fi enabled devices
2:34:10or connected to your uh to your network
2:34:13via ethernet or to your switch um so
2:34:15again to install it you can use any of
2:34:17the package managers you're comfortable
2:34:19with and we simply type in net discover
2:34:22and we hit enter so do have to get
2:34:24installed sorry
2:34:26and we hit enter and you can see already
2:34:28have it installed so using it requires
2:34:30root privileges so we say sudo
2:34:34net discover
2:34:36and then we specify the interface that
2:34:38we want to use so we can see enp2s0
2:34:42and hit enter and as you can see it will
2:34:44start scanning and it's doing this
2:34:45through arp or the address resolution
2:34:47protocol so arp
2:34:50request and response packets so again
2:34:52it's sending various arp requests
2:34:54to you know all ips on the network and
2:34:56then the responses give us the results
2:34:58that uh that actually prove that whether
2:35:01we have a device or not so you can see
2:35:04i currently have the my router which is
2:35:06running uh this is the default gateway
2:35:09and then i also have another device
2:35:11running here
2:35:12let's see if we have any other devices
2:35:15and we'll just wait for it to continue
2:35:16scanning
2:35:18so i'll just wait for this to continue
2:35:20scanning i think i have multiple other
2:35:22devices this is pretty much going to be
2:35:24my windows device if i bring up
2:35:27a mobile device here let's see if that
2:35:29actually
2:35:30comes up
2:35:32and i'll try and load up a website here
2:35:34i actually don't have my phone on me but
2:35:36in any case this essentially gives you
2:35:39all
2:35:40it essentially gives you all devices on
2:35:42your network and that's a great way of
2:35:44monitoring your network and viewing what
2:35:46devices you have so again it gives you
2:35:48the ip their mac address and their mac
2:35:50vendor so again it gives you an
2:35:52information about what device you're
2:35:53dealing with so in this case tp-link and
2:35:56then hot high precision which is pretty
2:35:58much a network adapter and once you're
2:36:00done you just hit ctrl c and that will
2:36:02terminate the process right over there
2:36:05all right now to end up at or to end
2:36:07this video
2:36:08let's talk about a dns which a lot of
2:36:10people actually ask me about so your dns
2:36:12information
2:36:14or your name servers rather are going to
2:36:16be stored in your resolve.com file so
2:36:18again sudo
2:36:20uh sudo and we'll use vim etsy and we're
2:36:24looking for the resolve uh
2:36:26resolve dot com file and we hit enter
2:36:29you can see that this uh this file is
2:36:30managed uh by the system they resolved
2:36:33uh and we can i'll actually show you how
2:36:35to use that utility shortly um
2:36:38so this is a dynamic result or
2:36:40configuration file for connecting local
2:36:42clients to the internal dns stub
2:36:44resolver of systemd so again it tells
2:36:46you that this is going through systemd
2:36:48and this is more of a dynamic uh of a
2:36:51dynamic file that is generated
2:36:53dynamically
2:36:54and again it is just for connecting
2:36:56local clients to the internal dns dns
2:36:59resolver with systemd resolved um and
2:37:02i'll be talking about services as i said
2:37:04later on but many people edit this which
2:37:06will work temporarily uh however if you
2:37:09do want to take a look at systemd
2:37:10resolve that's extremely simple so
2:37:13what you could do if you want to use
2:37:14this manually is uh we would actually
2:37:16just add another one here so i can say
2:37:19name server and then i'll say for
2:37:21example go the google name server eight
2:37:23eight eight eight
2:37:24and uh i can use that if i want to but
2:37:26in our case we're not gonna we're not
2:37:28gonna have any changes here so we'll
2:37:30just exit so
2:37:32you can actually check the status of
2:37:34system d resolve so we can say uh system
2:37:38b
2:37:39uh resolve sorry resolve and we say
2:37:42status
2:37:43and we hit enter and again that gives
2:37:45you uh the various dns information that
2:37:48you're looking for so we can print out
2:37:50so you can see the dns servers that we
2:37:52currently have set
2:37:54are going to be the google dns server
2:37:56and this is going through your uh your
2:37:58actual your router or your main gateway
2:38:01so it would be advisable to switch uh
2:38:04you know to any dns server that you want
2:38:06to do or that you want to use on your
2:38:08main router
2:38:09so you can see that it uses the default
2:38:12one that is your default gateway ip here
2:38:15and the google
2:38:17the google dns server that i have set
2:38:19here and that was simply for the
2:38:20demonstration purposes in this video so
2:38:23that's how to system they resolve
2:38:25um now when talking about your hosts
2:38:27file this essentially allows you to
2:38:29manage your various hosts and you can
2:38:31use this uh you know for ad blocking
2:38:33uh or yeah you can use it for ad
2:38:35blocking if you want to so for example
2:38:37uh we can say sudo
2:38:40vim and we say etsy and we say host and
2:38:43we hit enter and you can see uh for
2:38:45example where we have uh defined uh the
2:38:48local host or the loopback
2:38:50uh you know
2:38:52127.0.0.1 is our localhost and then the
2:38:55current host here which is alexis
2:38:57workstation is
2:38:59127.0.1.1 so i could also change that to
2:39:01any other ipa i want
2:39:03so if you're going to block an ad what
2:39:05you typically do is you put an invalid
2:39:07ip address here so i could say zero zero
2:39:09zero zero
2:39:10uh and i could sort of block a website
2:39:13here like for example
2:39:15i could say google.com
2:39:18which is not a smart thing to do but in
2:39:20any case uh we can write those changes
2:39:22and exit and then if i say sudo system
2:39:25control
2:39:26we say restart network
2:39:29manager i believe
2:39:31network manager dot service
2:39:33um so we will just let me just try and
2:39:35complete this for some reason it isn't
2:39:38displaying this system
2:39:41system control
2:39:46network manager.service
2:39:49and we want to use this so we want to
2:39:51restart the network manager and i'll
2:39:53actually show you this to you right now
2:39:55um so if we try and open up a firefox
2:39:58instance here and we say google.com and
2:40:01we hit enter you can see
2:40:03uh it pretty much redirects us to the
2:40:05local host and
2:40:07that's essentially how to use the hosts
2:40:09file now i can change the ip to
2:40:10something i do something else completely
2:40:12but again many of you have been asking
2:40:14me how to use the hosts file so that's
2:40:16pretty much how to use it
2:40:19and we can get rid of that right now
2:40:21because i don't want that to be the case
2:40:23and we can just restart the network
2:40:24manager one more time
2:40:26and there we are so we should be good
2:40:28there all right so that's pretty much
2:40:30all i wanted to cover in regards to
2:40:31networking and all that is important as
2:40:34i said we'll be taking a look at
2:40:35services i will also be taking a look at
2:40:37ssh and if you are interested in in
2:40:40exploring tools like netstat and net
2:40:43discover you can check my independent
2:40:45videos
2:40:50in this video we're going to be talking
2:40:51about how to use store and proxy gains
2:40:53in conjunction to anonymize your traffic
2:40:56uh you know through the use of any tool
2:40:57that you want so both of these tools
2:40:59don't come pre-installed on you know
2:41:01standard distributions but you can
2:41:03pretty much find them on pen testing and
2:41:05offensive distributions so again what we
2:41:08need to do is install the tor service
2:41:10first not the tor browser but the actual
2:41:13tor service and then secondly we need to
2:41:15install the proxy chains tool so again
2:41:17to install the tour service all we need
2:41:19to do is say sudo
2:41:21sudo apt you can use whatever package
2:41:22manager using sudo apt-get install and
2:41:25it's pretty much going to be just store
2:41:27that will be the name of the service and
2:41:28i already have it installed so
2:41:31again if you just want to check what it
2:41:33is so you can say what is store and this
2:41:34is referring to the actual
2:41:37um due to the actual service so you can
2:41:39see that what is a second generation
2:41:41onion router
2:41:43so if we say man
2:41:44tor and we hit enter you can see that
2:41:46door
2:41:47uh is a connection oriented anonymizing
2:41:49communication service users i choose a
2:41:51source routed path through a set of
2:41:53nodes
2:41:54uh and negotiate a virtual circuit
2:41:56through the to the network i think i've
2:41:58pretty much explained this before in
2:41:59previous video as to how the tor how tor
2:42:02works um so we'll be using tor now uh to
2:42:04start the tour service we can use
2:42:07systemd or you can also use a service
2:42:10um so we can say sudo system control and
2:42:13we say uh we can say start and then we
2:42:16are looking for tor uh
2:42:19i think where it is the tor service here
2:42:22uh i'm not too sure what it is what it's
2:42:25called so if we say tor
2:42:27let's check the status here
2:42:29status store
2:42:31and you can see that we currently have
2:42:32it loaded and active so again the tor
2:42:36service is an anonymizing overlay
2:42:38network for tcp so if we use netstat
2:42:41here so we can say netstat
2:42:43and we can look for listening tcp
2:42:46connections and we grip for the port
2:42:48that the door service connects through
2:42:49which is 1950 and we hit enter you can
2:42:52see we now have uh you know we are
2:42:53listening on port 9050 and this is
2:42:56localhost so that's perfect we can use
2:42:58this with proxychains all right so now
2:43:00let's talk about proxychain so again uh
2:43:02installing proxychains is very simple so
2:43:04you do upgrade install proxychains uh
2:43:07sorry um
2:43:09proxy chains and we enter and i already
2:43:11have it installed uh before we actually
2:43:13use it we now need to uh we need to play
2:43:16around with the configuration file so
2:43:18that we can tweak the the configuration
2:43:20to what we want it to be and how we want
2:43:22it to work so we can say sudo vim hc
2:43:26proxychains.conf and we hit enter
2:43:29so again
2:43:30pretty much i'll go through the settings
2:43:32that i use so again
2:43:34we can use http x4 sox5
2:43:37uh and again we this allows you to
2:43:39tunnel um or proxy you can you can
2:43:42essentially tunnel your connections
2:43:43through a series of proxies and in our
2:43:46case the proxies are going to be is
2:43:47going to be tor so with dns that's the
2:43:50great thing so
2:43:51uh the options below identify how the
2:43:54proxy list is treated only one option
2:43:56should be common uncommented at a time
2:43:58so
2:43:59dynamic chains where each connection
2:44:02will be done via chained proxies all
2:44:03proxy chained in order as they appear in
2:44:05the list at least one proxy must be
2:44:07online to play in the chain i i pretty
2:44:09much like using the random chain
2:44:12so you can see that each connection will
2:44:14be done via random proxy or proxy chain
2:44:17from the list this option is good to
2:44:18test your intrusion detection system
2:44:20because it's constantly changing uh you
2:44:23know through random proxies but if again
2:44:25if you want a dynamic chain that's
2:44:26perfect
2:44:27uh you can also use the strict chain
2:44:29this will ensure that uh all connection
2:44:32are going to be done through a chain
2:44:33proxy or all proxies will be chained in
2:44:35the order as they appear in the list so
2:44:38i like using a random chain so you want
2:44:40to uncomment this or it will be
2:44:42commented here so
2:44:44if i just hit insert here and it'll
2:44:46pretty much be commented like so and you
2:44:48want to uncomment this
2:44:50we then want to take a look at the proxy
2:44:52dns request so again this will prevent
2:44:55no leak for dns data this is very
2:44:57important you want to make sure that's
2:44:59uncommented and then we want to take a
2:45:02look at the proxy list format so this
2:45:03gives you an idea of how to use your
2:45:05proxy list if you are interested in
2:45:07using other proxies apart from tor
2:45:10you can see that we have socks 5 http
2:45:12sox4 you know in our case the defaults
2:45:15will be set to door and we want to add
2:45:17socks 5 as well here so we say socks 5
2:45:20and we can we remember it's running on
2:45:22our local host uh sorry 127.0.0.1
2:45:26uh 1950 and that's of course going to be
2:45:28um that's going to be socks 5 all right
2:45:31so we can add any of the other proxies
2:45:33we want here so again if you're not keen
2:45:35on using tor you can change this and
2:45:37we'll write changes and quit from here
2:45:40so now when using proxy chains you want
2:45:42to ensure that you have the toss service
2:45:43started and it's currently running and
2:45:45then i use the syntax is very simple so
2:45:47we say proxy chains
2:45:50and then we specify the tool that we
2:45:52want to use um so for example
2:45:55i can say proxy chains are firefox uh or
2:45:58i can use another tool like ssh or
2:46:01telnet
2:46:02or i could use a tool uh maybe let's try
2:46:05firefox because it's the easiest way to
2:46:07test this so i say firefox
2:46:09and then i open this website dns
2:46:11leaktest.com
2:46:13and we hit enter and that's going to
2:46:15start proxy chains for us now given that
2:46:17it's using door the connection is going
2:46:19to be much slower than you know a
2:46:21standard proxy uh of course depending on
2:46:23what proxy you end up using so we'll
2:46:25just wait for this to load up and the
2:46:26dns lictest.com
2:46:28will tell us what our ip is and secondly
2:46:31it will tell us
2:46:33what our dns is so you can see
2:46:36it gives us information regarding our ip
2:46:38um for some reason isn't telling us what
2:46:40country it is so again we can just hit a
2:46:42standard test this will test our dns to
2:46:44see if we
2:46:45are leaking any dns information and of
2:46:48course dns information is very important
2:46:49as it can leak your geographical
2:46:51information so again you can just go
2:46:54through the test and this will display
2:46:56whether or not what dns servers you're
2:46:58currently been using so let's wait for
2:47:01this and see what results we get there's
2:47:03a progress bar right over here so you
2:47:05can see that all are going through um
2:47:08dns servers in germany and of course you
2:47:11have their host names and their various
2:47:13ips so again that's a great because it
2:47:15was a we were we didn't leak any of our
2:47:18personal dns information that or the dns
2:47:20servers we went through but of course
2:47:22that is also dependent on on you know
2:47:25dns security something that's out of the
2:47:26scope of this video
2:47:32in this video we're going to be talking
2:47:33about uh process and service management
2:47:36uh so we're going to be talking about
2:47:37lots of tools that you can use to uh to
2:47:39manage processes
2:47:41and also manage services right so these
2:47:44this is a very important video pretty
2:47:45much i think one of the most important
2:47:47videos in this series because of of the
2:47:50power that that comes with it so uh
2:47:52first of all let's let's take a look at
2:47:55some of the utilities that you can use
2:47:57uh to to manage system resources and to
2:48:00view the current processes and you know
2:48:02just view resource consumption in
2:48:04regards to the processes that are
2:48:06consuming the most and consuming the
2:48:07least
2:48:08now by default all linux systems come
2:48:10with a utility called top right and you
2:48:13can pretty much get some information
2:48:15about it by using uh the what is command
2:48:17so again it tells us that top displays
2:48:19linux processes so you can hit top and
2:48:21again as you can see this gives you
2:48:23information regarding uh your your
2:48:25system resources the consumption and the
2:48:28various processes that are running the
2:48:30the owner of the processes in terms of
2:48:32the user so you have your process id
2:48:34very important there that can be used to
2:48:36manage the process either to kill it
2:48:38uh or to stop it you then have the user
2:48:41here that it belongs to
2:48:43you then have the cpu and memory
2:48:45consumption
2:48:46uh the time
2:48:47and the command itself so again you can
2:48:50essentially use this to manage all your
2:48:52processes however the a better utility
2:48:55custom utility that you can install by
2:48:57with with whatever the package manager
2:48:59using
2:49:00and that is the h-top utility so again
2:49:02we can install it we can install it here
2:49:04i already have it installed so again we
2:49:07can clear this and say what is h-top you
2:49:09can see that this is an interactive
2:49:11process viewer so if we open up htop uh
2:49:14you can see that first of all it gives
2:49:15you your processor usage
2:49:17in regards to how many cores you have so
2:49:19i have six scores here and it gives you
2:49:21the utilization in terms of percentage
2:49:24you then have your memory usage so it
2:49:25gives you a total usage i have about 16
2:49:28gigs here and i'm currently using six
2:49:30gig
2:49:30uh it also tells you your swap usage uh
2:49:33so i have a swap uh set to about two
2:49:36gigs uh don't get angry at me and a lot
2:49:37of people are against swap nowadays
2:49:40it gives you the amount of tasks
2:49:43the amount running the load average and
2:49:45the uptime of your system so very useful
2:49:47information it also sorts it out it
2:49:50sorts the information out uh you know
2:49:52similar to what we add so we have the
2:49:53process id and you can sort that out uh
2:49:56chronologically so you can say you can
2:49:58just click on it and it loads it up from
2:49:59the first process with the process id of
2:50:02one you then have the user so you can
2:50:04again switch from all the user uh the
2:50:06user accounts that uh that these
2:50:08processes are running under
2:50:11you then have your cpu usage so if i
2:50:12click on cpu that displays uh the the
2:50:15process that is currently using the most
2:50:18uh cpu usage uh again i can click on
2:50:20memory and it tells us that google
2:50:22chrome is using the most memory that's
2:50:24that's not a surprise
2:50:26and of course we can just go back to cpu
2:50:28usage and you can see that obs is
2:50:30currently running right now which makes
2:50:31sense as that is using the most cpu
2:50:34right so uh this is a utility that you
2:50:37can use to pretty much manage your
2:50:39processes now before we take a look at
2:50:40how to use it because this simplifies
2:50:42the process
2:50:43let's take a look at uh you know how you
2:50:46would actually view these uh the
2:50:48resource consumption like ram usage for
2:50:50example to v ram ram usage we would
2:50:53simply type in free
2:50:54and that again tells you uh if we that
2:50:57you know we just use the man pages here
2:50:59you can see that free uh displays
2:51:02the amount of free and used memory in
2:51:04the system so again you can display this
2:51:06uh in regards to uh to to to the output
2:51:09you want so if we say three h that
2:51:11prints it out in human uh readable
2:51:14format so you can see we have total used
2:51:16free shared
2:51:17the cash and available and of course
2:51:19also for your swap so that's uh one of
2:51:21the quick ways you can view how much ram
2:51:23you're using
2:51:24now let's talk about processes right so
2:51:26processes uh need to be understood as
2:51:29you need to separate them between you
2:51:31need to separate processes and services
2:51:33right so processes
2:51:35uh are viewed with the ps tool so again
2:51:38uh ps uh gives you a report uh it gives
2:51:40you a report of this uh or it
2:51:42essentially gives you a snapshot of your
2:51:43current processes that you have running
2:51:46all right so if i just say ps
2:51:48this is weird because many users
2:51:50actually i've pointed this out so why
2:51:53does it only give you two processes well
2:51:55you haven't specified any arguments in
2:51:57regards to what processes you want to
2:51:58see so what it's going to give you is
2:52:00it's simply going to display processes
2:52:02that are in your current shell and you
2:52:04can see that the tool that it has is the
2:52:06bash
2:52:07and the the actual command that you run
2:52:09so that makes sense now if we want to
2:52:11display all processes we would simply
2:52:13say psa ux
2:52:15and you can view all of this syntax
2:52:18from the man page which is actually
2:52:20recommended here i'm using the psd style
2:52:22or the bsd syntax so again
2:52:25to see every process on the system using
2:52:28standard syntax you can use that i'm
2:52:29using as you can see right over here bst
2:52:32syntax so i'll continue with that so i
2:52:34can say ps aux
2:52:36and i can hit enter alright so this is a
2:52:38lot of information here this is
2:52:40essentially giving you a snapshot of all
2:52:42the processes that you have running on
2:52:44your system so we can scroll all the way
2:52:46to the top and again the it's sorted out
2:52:48into a table with various columns so
2:52:50again you have the user the process id
2:52:52and it starts chronologically
2:52:54but the great thing about tools like
2:52:55h-stop is it gives you a dynamic view of
2:52:58of the processors how much they're
2:53:00consuming on a second by second basis uh
2:53:03cpu usage memory etc but this is a
2:53:05snapshot remember so again this can give
2:53:07you an idea of all the processes that
2:53:09are currently active however if you want
2:53:11a dynamic idea of the current system
2:53:14resource consumption use a utility like
2:53:16top or h-top this just gives you a
2:53:18snapshot all right the key thing we're
2:53:20looking for here is the pid because we
2:53:23won't talk about managing processes
2:53:25right so
2:53:26let's say um i want to start a service
2:53:29here
2:53:30so i say sudo system
2:53:32control
2:53:35system control i'm going to say start
2:53:38and i'll say tor i want to start the tor
2:53:40service here and then i say ps aux i can
2:53:42also grab the output here and i can say
2:53:44i'm looking for tor uh so give me all
2:53:47processes with door right now of course
2:53:49it's going to give us you know various
2:53:51other false positives with the the
2:53:53string of characters t o r and you can
2:53:56see the inclusion of that within storage
2:53:58but if we just go to the bottom here uh
2:54:00you can see we have um
2:54:03we have the user bin tour uh binary
2:54:06being used here so that looks
2:54:07interesting
2:54:08and yeah so if we take a look at the
2:54:10process id we can see it has a process
2:54:12id of 7604 so if we say uh sudo
2:54:16system
2:54:17control we say status status store and
2:54:21we enter um sorry about this guy system
2:54:25control and we hit we take a look at the
2:54:27status of the
2:54:28of the service you can see that it's
2:54:30active it's loaded and active so if we
2:54:32want to kill this process all we need to
2:54:34do is get the process id in this case
2:54:36it's going to be 7604
2:54:39and all we need to do is say
2:54:41we just say kill
2:54:43and you may want to prepend this with
2:54:45root privileges or the pseudo command so
2:54:47we say sudo kill
2:54:48uh seven six zero four seven six zero
2:54:51four and we enter and now if we take a
2:54:53look at the the the tour service you can
2:54:55see it's still running now the reason i
2:54:57did this is because you need to
2:54:59differentiate between a service and a
2:55:02process because the service will re
2:55:04reinitiate or re-initialize itself right
2:55:07so let's take a look at
2:55:09the let's take a look at all the
2:55:11processes here and we can take a look at
2:55:12more realistic options available to us
2:55:15right so i'll give you an example here
2:55:17um so let's grip for ssh and we'll say
2:55:22grep ssh
2:55:24let's see we have the ssh daemon here
2:55:27[Music]
2:55:29which is running as a process id
2:55:32of
2:55:345687 right and
2:55:36we also have the uh yeah that's pretty
2:55:39much the one we're looking for we also
2:55:40have the ssh agent here
2:55:42so what we can do is we can say um
2:55:45pseudo here
2:55:46one nine six nine
2:55:48and we can also say pseudo kill 56 87
2:55:51right so we can say 56 87 you kill that
2:55:55and then we say system
2:55:57system
2:55:58control and say
2:56:00status ssh and we hit enter you can see
2:56:03that ssh
2:56:05is currently loaded but inactive dead
2:56:08right so that's just a simple way of
2:56:10managing processes now we can do the
2:56:11same thing
2:56:12uh with h-stop and i'll show you how to
2:56:14do this many people actually skip this
2:56:16but each stop is has a much easier way
2:56:18of doing this so when you launch h-stop
2:56:21uh you can pretty much filter through
2:56:22the results but a great way of searching
2:56:24for services by their name instead of
2:56:25using grep is by using the f3 key
2:56:28after which it will bring up this little
2:56:30search bar and i can search for things
2:56:31like door
2:56:32uh and if i use a space
2:56:34it pretty much should give me all the
2:56:36results so let me just do that one more
2:56:38time so i say tor
2:56:40and
2:56:41we can see that the process was closed
2:56:44but the the service is still running so
2:56:46let's try another another process here
2:56:49let's see if we have um
2:56:52let's see let's actually work with
2:56:53h-stop i just want to show you this so
2:56:54if we click on h-stop and it's
2:56:56highlighted yellow we can actually kill
2:56:58it by using f9 so if we hit f9 we can
2:57:01send various signals to this process so
2:57:04we can say signal quit signal kill so if
2:57:06we say signal kill that's option nine
2:57:09and we hit enter
2:57:10you can see that that will pretty much
2:57:12kill the process and you can see that it
2:57:15actually points that up right over here
2:57:17and
2:57:17you can see that the output is messed up
2:57:19and i shouldn't have probably done that
2:57:21but i wanted to demonstrate the power of
2:57:22h stop here so if i go into h stop one
2:57:25more time and now again it's giving us
2:57:27our dynamic results so we can pretty
2:57:29much use that same
2:57:30syntax to manage our services really
2:57:32easy and many people go over this it's
2:57:34not just a system resource uh
2:57:37usage
2:57:38utility to actually display how much uh
2:57:40you know resources you're consuming it
2:57:42can actually allow you to interact with
2:57:44your services or your processors quite
2:57:46well so
2:57:48again i can search for any process right
2:57:50over here with name or i can
2:57:52again i can work with the the resource
2:57:55consumption so again i can highlight
2:57:56resource consumption here uh memory
2:57:58consumption et cetera et cetera right
2:58:00now let's talk about service management
2:58:02with system d right because i also want
2:58:05to cover uh system v as well system v
2:58:07service management but
2:58:09now the norm is increasingly becoming
2:58:12system d so it's great to to actually
2:58:14know how to use this so
2:58:16if we say man system
2:58:18control this is the utility that allows
2:58:20us to control um
2:58:22so you can see control the systemd
2:58:24system and service manager so i'll show
2:58:26you how to use it so if we want to list
2:58:28all the active services which are going
2:58:30to be a lot we can say system
2:58:32uh control and we hit enter and you can
2:58:35see that we can you know we can move
2:58:36down with the uh your your directional
2:58:39keys
2:58:40and this gives you an idea of all the
2:58:41services that you have running and once
2:58:43you have once you're done we have about
2:58:45uh 230 lines here and they keep on going
2:58:47as as the more you you actually go down
2:58:50so uh 269 loaded units um it gives you
2:58:54all information regards to all the
2:58:55services you have running so if we quit
2:58:58we can also prep so if we grep here we
2:59:01say grab
2:59:02ssh and we hit enter so we have no ssh
2:59:05service running so if we if we want to
2:59:08start a service like the ssh service
2:59:09what i can do is i can say
2:59:11system control
2:59:13system control i say start and then i
2:59:17i can you know then play around with
2:59:19with what i want to do so i can say
2:59:21um i can say
2:59:24start and then the name of the service
2:59:25so i can say ssh and then i can use the
2:59:27tab auto completion here so again you
2:59:29can see that we have the ssh socket and
2:59:31the ssh service so if i wanted to start
2:59:34the ssh service uh just give it a few
2:59:36seconds it does take a while to load
2:59:37this if i use tab auto completion too
2:59:39much so if i say
2:59:41system control uh start ssh service and
2:59:43i hit enter it's gonna ask me for my uh
2:59:45for my password and it's gonna this
2:59:47because it requires root privileges
2:59:49so uh that has started the ssh service
2:59:51now we can again uh confirm this uh with
2:59:54you know we can say uh lt here and uh
2:59:57you can see we have ssh running
2:59:59right over here so again we can check
3:00:01the status of the pros of this actual
3:00:03service by running uh sudo system
3:00:06control and we can say status
3:00:09ssh dot service here and we enter
3:00:12and there we are so you can see it tells
3:00:14us that the ssh service this is using
3:00:16open ssh so it tells us it's loaded and
3:00:18active which means it you can actually
3:00:20use it and it gives you information
3:00:22about it so the log of events so again
3:00:25started uh ssh listening on port 22
3:00:29listening on localhost port 22 starting
3:00:31the openssh openbsd secure shell server
3:00:35and it gives you the various timestamps
3:00:37right so
3:00:38that's how to pretty much interact uh to
3:00:41how to start and monitor the status of a
3:00:43service if you're having issues with it
3:00:45right now if i wanted to disable it or
3:00:47to stop it i could say um i could just
3:00:51i can say stop
3:00:53uh and i can say ssh dot service and i
3:00:57hit enter and that will stop the
3:00:59sorry let me just enter my password here
3:01:01that will stop the service
3:01:03if i check the status you can see that
3:01:05it's loaded but inactive and dead now a
3:01:07lot of people ask me how do i run
3:01:10particular services on system startup
3:01:12and you can easily do that with systemd
3:01:15so i can say sudo system let's say i
3:01:18wanted to enable the ssh service every
3:01:19time i boot up which is useful
3:01:22so i can say system control
3:01:25[Music]
3:01:26and then i would say enable but first i
3:01:28need to check if it's already enabled so
3:01:30i can say is enabled
3:01:32and then say ssh dot service and that
3:01:35will tell me if uh it is currently
3:01:37enabled to
3:01:38do to be run on system startup you can
3:01:40see tells us that it's currently
3:01:41disabled which is great
3:01:43uh if i check the synergy service i just
3:01:46want to give you an example a robust
3:01:47example or hit enter you can see that on
3:01:50startup yes this service is enabled
3:01:52that's because i use the synergy service
3:01:54to you know for my mouse sharing my
3:01:56mouse and keyboard sharing
3:01:58system so again that tells me that okay
3:02:00that's enabled so if we want to enable
3:02:02ssh what we would say is a pseudosystem
3:02:05control and we would say enable and say
3:02:07ssh.service
3:02:10all right and i hit enter and you can
3:02:12see it's created the sim link
3:02:14for us uh in the system d uh directory
3:02:17here so
3:02:19uh if you're using um
3:02:22if you're using system v then you nee
3:02:24you need to play around with the initial
3:02:26uh the init scripts uh
3:02:28and you then need to create a sim link
3:02:30but this does it automatically for you
3:02:31so now if we check the uh is enabled if
3:02:34we check if it's enabled you can see
3:02:35that now it's enabled if i want to
3:02:37disable it from running on startup i
3:02:39would simply say disable
3:02:42because i don't want ssh running this is
3:02:44not a server so
3:02:45i can check it now and we can see it's
3:02:47disabled all right so
3:02:49that's pretty much how to manage uh you
3:02:51know services with system d so that's
3:02:54how to start stop uh if i want to
3:02:55restart a service again i can simply say
3:02:58restart so let me do that right now so
3:03:00if i say sudo system control i say tor
3:03:03sorry start
3:03:04tor i can hit enter that will start the
3:03:06tour services i want to reload it i can
3:03:08say reload
3:03:10all right now i can also um
3:03:14i can also reload will reload the uh the
3:03:17configuration if i say restart that will
3:03:19simply restart the service with the
3:03:21current configuration so that's a quick
3:03:23tidbit for you if you you can use reload
3:03:25here then that will essentially restart
3:03:28it with the newer configuration so in
3:03:30case you're wondering so i'll just stop
3:03:31this service
3:03:32and i'll just hit enter
3:03:34and there we are all right so
3:03:36that is how to manage services now if
3:03:38you want to uh if we want to reload the
3:03:41entire the system d daemon what we can
3:03:43say is sudo system control
3:03:46uh we're looking for the daemon and we
3:03:49can say reload and we just hit enter and
3:03:51that will reload the daemon completely
3:03:53that's if you're having any issues and
3:03:55you wanted to reconfigure particular
3:03:56services
3:03:58all right
3:03:59now
3:04:00let's talk about system v service
3:04:02management which many of you are
3:04:03familiar with a system v is essentially
3:04:05where you say service
3:04:07the name of the service which could be
3:04:08door and then we say start
3:04:10we can say stop
3:04:12and we can say restart right very very
3:04:14simple and we can also check the status
3:04:16so again say service store start
3:04:18that will ask you know ask me for my
3:04:21administrator privileges i can say
3:04:23service store
3:04:25status hit enter you can see it tells us
3:04:27active loaded
3:04:29um and then we can say system a service
3:04:32store we can say stop and we can hit
3:04:34enter and that will stop these the door
3:04:36service and we can also
3:04:38say restart and again that will simply
3:04:40restart the tour service there and we
3:04:42can then stop it one more time so that's
3:04:44how to use system v very very simple but
3:04:46in my opinion system d
3:04:48uh is is the much better alternative to
3:04:51learn now and it's extremely robust and
3:04:53very very powerful tool to actually
3:04:56learn how to use or do low utility
3:05:02in this video we're going to be talking
3:05:03about ssh uh how to configure it
3:05:05securely
3:05:06uh and then of course we'll talk about
3:05:08you know how to uh how to securely
3:05:10transfer files with ssh so let's get
3:05:12started um first of all with
3:05:14establishing what ssh client and server
3:05:17we're going to be using so in our case
3:05:19we want to be uh we want to be using
3:05:21openssh which is pretty much the go to
3:05:23uh the the go to ssh client in server
3:05:26solution it's completely open source and
3:05:28it's uh it's one of these uh you know
3:05:30great services so again that was uh
3:05:32developed by the bsd team
3:05:34so um again uh we must first of all
3:05:38understand the uh the connection type or
3:05:40the connection model uh with ssh so ssh
3:05:43is primarily a client server connection
3:05:46model so that means you need the client
3:05:48software to
3:05:49connect to the to the server software in
3:05:51our case we need to install the openssh
3:05:54client service or the client package
3:05:57on our client and of course the openssh
3:05:59server package on r7 i'll show you that
3:06:01right now so i'm currently on my client
3:06:02here which is going to be ubuntu our
3:06:04remote server is going to be one of my
3:06:05ubuntu servers uh running on my
3:06:07virtualization server so
3:06:09what i'll do is i'll say sudo apt
3:06:13get install and we say open ssh and we
3:06:16we're looking for the openssh if we
3:06:18double tap we can see we're looking for
3:06:19the openssh client right so i'm gonna
3:06:21hit enter and uh i already have this
3:06:24installed right now the openssh client
3:06:27configuration file is found so if i say
3:06:29cat hc ssh sorry ssh and this is found
3:06:33under
3:06:33it is the ssh config the sshd config
3:06:36file is for the open ssh server
3:06:39so you can see i also have my uh my my
3:06:42public and private keys here as well but
3:06:44i'll get into that in a second they we
3:06:46don't need to complicate this right now
3:06:47so if i take a look at me at my config
3:06:50file here this is the client config
3:06:53you can see that um
3:06:55the options are quite uh straightforward
3:06:58in regards to what you can enable and
3:06:59disable so you can specify the port
3:07:02uh the protocol um
3:07:04and uh various other bits of
3:07:06you know configurations here but that's
3:07:08not the the in within the scope of the
3:07:11video but i just wanted to get to that
3:07:13so
3:07:13uh my remote server is running on um
3:07:16it's currently running on an ip of
3:07:20192.168.1.113 so
3:07:22we already have an admin user on that
3:07:23system so we'll just say admin and we'll
3:07:25say 192.168.1.113
3:07:28all right and i will just enter the
3:07:31password here for the admin user and
3:07:33there we are so you can see i'm
3:07:34currently logged in as the admin user so
3:07:38the first thing we want to do is we need
3:07:39to install uh the openssh server so you
3:07:42say oh apt-get install open ssh
3:07:44server and the reason i'm doing this
3:07:46even though i have it installed already
3:07:48just to show you how one would go about
3:07:49doing it right
3:07:51um so hit install already installed
3:07:53there excellent all right all right all
3:07:55right now that we have this uh both the
3:07:57pieces of software installed on the
3:07:59client and the server
3:08:00we can talk about uh configuring uh you
3:08:03know ssh right so pretty much when
3:08:06dealing with the remote server and
3:08:08remote authentication the first thing
3:08:10you need to do is you need to disable
3:08:12root logins
3:08:14uh because the root the root user
3:08:16account is extremely powerful because it
3:08:18really has no restrictions in regards to
3:08:19what it can do so that's our first order
3:08:21of business here and this can be done by
3:08:24modifying
3:08:25this can be done by modifying the
3:08:26openssh
3:08:28the openssh
3:08:30configuration file the opensh server
3:08:32configuration file so if i say sudo vim
3:08:35hc ssh and we're looking for sshd
3:08:39uh sshd and we say
3:08:42sshdconfig and we hit enter so you can
3:08:44see this is the openbsd openssh
3:08:46sshdconfig file
3:08:48and it does you it tells you here this
3:08:50is a sshd server systemwide
3:08:53configuration file so the first thing we
3:08:54want to do is we let's take a look at
3:08:56some of the various uh configurations
3:08:58you can set here so you can change the
3:09:00default port this is great for those of
3:09:02you who are who want to set up a
3:09:03honeypot on that exact port like por 22
3:09:06and then have ssh run on another port
3:09:08like 2 2 2 0
3:09:10you can do that as well
3:09:12you can also change the listen address
3:09:14if you want to uh the host key names uh
3:09:17let's talk about uh let's just go down
3:09:20into logging you can play around with
3:09:22logging here
3:09:23uh and i'll talk about logs probably in
3:09:25another video and here we are we have uh
3:09:28we have authentication all right so
3:09:29within authentication you can see we
3:09:31have an option called permit root login
3:09:34right and we want to change this to no
3:09:36right so from yes to no
3:09:39uh and we we can also play around with
3:09:41the grace the login grace time so we can
3:09:44increase this or decrease it based on
3:09:46the on the time you want to provide
3:09:48uh we can keep strict modes to yes uh in
3:09:52regards to the max authentication tries
3:09:55we can change this to four although i'll
3:09:57be making a separate video where i'll be
3:09:59showing you how to set up ssh brute
3:10:01force protection the max sessions i want
3:10:04are going to be three public key
3:10:06authentication
3:10:08uh yes uh let's go all the way down now
3:10:11um
3:10:12and we are primarily looking for
3:10:14password authentication so we'll talk
3:10:16about this when we're going to be
3:10:17setting up ssh keys so for now we've
3:10:20we've essentially disabled uh where
3:10:22we've disabled the root logins so if i
3:10:24just save the the files here now when
3:10:27whenever you've made changes to the uh
3:10:29to the open sh server configuration file
3:10:32we need to restart uh the open ssh
3:10:35server so to do this again we'll use
3:10:37systemd so say system
3:10:40and we say
3:10:42restart
3:10:44sshd sshd service remember this is the
3:10:47sshd daemon or the openssh server and we
3:10:49hit enter
3:10:50all right so now pretty much if we just
3:10:53open up a new tab on my client and i try
3:10:55and log into the root user account i
3:10:57would say ssh root and i would say 192
3:11:00168.1.113
3:11:03and hit enter right and i enter the
3:11:04password for the root user
3:11:07and
3:11:08you'll see pretty much that we will not
3:11:10be able to do it so
3:11:12uh that is pretty much uh going to block
3:11:14any logins to this uh to this particular
3:11:17account now the other thing we we want
3:11:19to do is we want to disable or we want
3:11:21to lock
3:11:22the password for the
3:11:25we want to lock the password for the
3:11:26root account this will ensure that
3:11:28even though
3:11:30a person or an attacker may have
3:11:33the password the legitimate password
3:11:35they can get through it through another
3:11:36user account because remember remember
3:11:39if if a user gets access to the admin
3:11:42account via ssh they can easily switch
3:11:45to the root user account so we also have
3:11:47to disable you know the password login
3:11:50here and this will pretty much lock the
3:11:52account unless we have the privileges to
3:11:54actually change the password manually
3:11:56and to unlock it but it's a great way of
3:11:58of you know
3:12:00protecting yourself from script kiddies
3:12:01so
3:12:02what we can do is we can say um we can
3:12:05use the password command and say
3:12:06password uh l and we specify the account
3:12:09we or
3:12:10the the account whose password we want
3:12:11to lock and we hit enter uh we need uh
3:12:14pseudo privileges here so you say sudo
3:12:16hit enter and the password expiry
3:12:18information has changed so you can say
3:12:19sudo
3:12:20password and then status
3:12:23i believe it's status what options can
3:12:25we specify here
3:12:27root uh
3:12:28wait enter no we do not want to enter a
3:12:30new password so we can just do this one
3:12:33more time here so you can see that i can
3:12:34actually change the password but let me
3:12:36lock it
3:12:37um
3:12:39root where is the status how do we check
3:12:42the status oh yeah there is a capital s
3:12:44so if we hit enter you can see that the
3:12:46password is now going to be locked now
3:12:48uh the second step would be to disable
3:12:51password authentication and to use ssh
3:12:54keys which is exactly what i'm going to
3:12:56show you right now
3:12:57so that will pretty much ensure that
3:13:00you're protected from brute force
3:13:01attacks because you're pretty much
3:13:03ensuring that you cannot log into this
3:13:05ssh server
3:13:06without an ssh key right so
3:13:10uh what we'll do is we will create a new
3:13:12ssh key here and this is very this is
3:13:15very easy to do so uh first of all uh we
3:13:18need to uh we need to establish
3:13:21uh what user account we're going to be
3:13:24you know pretty much be using we've
3:13:26already locked out the root account
3:13:28and once we set up the ssh keys we'll be
3:13:30pretty much logging into the admin user
3:13:32account and the asset the ssh keys
3:13:35or the ssh key based authentication will
3:13:37only allow us to to access the admin
3:13:39account
3:13:40after which we will we will modify the
3:13:43uh the openssh server configuration file
3:13:45to disable
3:13:46uh password authentication so what we'll
3:13:48do is we'll say um
3:13:51ssh keygen
3:13:53um
3:13:54there we are t rsa and we hit enter and
3:13:57it's going to ask us for
3:14:00uh it's going to say generating public
3:14:02private
3:14:03rsa key pair enter the file in which to
3:14:06save the key so we'll say
3:14:09home oil just leave it in this directory
3:14:10hit enter we can enter a passphrase
3:14:12that's always recommended i'll enter
3:14:14password is here that will also add an
3:14:16additional level of security to your ssh
3:14:18key because remember the ssh private key
3:14:21has to be kept secret so
3:14:23we can see that the keys have been
3:14:25copied into a home alexis and ssh
3:14:27directory here so
3:14:29pretty much what we can do now
3:14:31is uh if we change our directory into
3:14:33the ssh directory here you can see that
3:14:36we have the public and private keys
3:14:38right over here so what we need to do
3:14:40now is we need to copy the uh the public
3:14:43key onto the server so let me just
3:14:44explain how ssh works really quickly how
3:14:47the authentication works
3:14:48so you store your public key on your on
3:14:51the server and you have your private key
3:14:53uh with you and the private key is the
3:14:55most important as it's the
3:14:57it's pretty much the key that will allow
3:14:59you to authenticate successfully with
3:15:01the server so you need to keep it secure
3:15:03and backed up in the event you lose it
3:15:05you lose access to the server that's
3:15:07very important right
3:15:08so essentially what what's going to
3:15:10happen here
3:15:12is your private key is used for
3:15:13encryption right so your server the ssh
3:15:15server will use your it will send a
3:15:18random string of data to you the ssh
3:15:20client uh after which the ssh client
3:15:23will encrypt that a random string of
3:15:25data with the private key and send the
3:15:27encrypted data
3:15:28uh to the server the server will then
3:15:30use your public key to decrypt it and if
3:15:33it then matches and you know so on and
3:15:35so forth i'll explain that in a second
3:15:37so
3:15:37what we can do now is we need to copy
3:15:39this uh so we say ssh
3:15:41copy
3:15:42id and we specify uh the the server so
3:15:46we say
3:15:48192.168.1.113 and we hit enter
3:15:50it's going to ask you you can see it's
3:15:52asking for the user alexis but we don't
3:15:55want to do this remember because we want
3:15:57to use the uh the user admin so we're
3:15:59going to say admin and we're gonna hit
3:16:01enter it's gonna ask for admins password
3:16:04like so and uh
3:16:06you can see after we've entered the
3:16:07password it's gonna ask us for the it's
3:16:09gonna tell us the number of keys added
3:16:10is one
3:16:11and we can now try try login to the
3:16:13machine with ssh admin and we will
3:16:16essentially not have uh we will not need
3:16:18to use passwords but before we do that
3:16:21we need to disable password
3:16:22authentication with ssh so to do this
3:16:24again we say sudo vim and i'm back on
3:16:26the server now ssh
3:16:29and we say sshd config and we hit enter
3:16:32and
3:16:33we'll go all the way to the bottom here
3:16:36uh am i in the right configuration file
3:16:38i believe so
3:16:41yes we are i believe uh your possible
3:16:44authentication right over here
3:16:46and we will change this to no so this
3:16:49will
3:16:49essentially disable the ability for you
3:16:52to log in to this or to this remote
3:16:55server via ssh with passwords so the
3:16:57only way you can login
3:16:59is going to be through ssh keys so now i
3:17:02can
3:17:03write changes and exits here and we'll
3:17:06restart the
3:17:07ssh server
3:17:09service or the sshd service we enter and
3:17:12that's going to restart it for us orange
3:17:14so now if we exit
3:17:16we can essentially say ssh
3:17:18admin
3:17:20at 182
3:17:23168.1.113.8 enter and it's going to ask
3:17:25me for the passphrase for the for the
3:17:27private key and we're going to unlock
3:17:29and there we are we now have access
3:17:31right now some of you might be saying
3:17:33well uh you have the private key what if
3:17:36the location is different so let me just
3:17:37show you this right now so i'll go into
3:17:39my ssh directory here
3:17:42and uh
3:17:44just list all the files and i'll say
3:17:46i'll move the um
3:17:48this is sorry sorry about that let me
3:17:50just go to my local directory here or i
3:17:51can actually just log out
3:17:53so cd ssh
3:17:55and what i'll do is i'll move the
3:17:57private key so i'll say move id
3:18:00rsa to uh
3:18:02sorry to my desktop and i'll hit enter
3:18:05and now if i try and log in so i say ssh
3:18:08uh admin
3:18:10sorry uh
3:18:12states
3:18:14enter you can see it logs in just fine
3:18:16however if if i didn't know the location
3:18:18what i would say is for example let me
3:18:21just exit i would say for example if i
3:18:23was logged in on another computer
3:18:25i would then say uh so again let me just
3:18:28go on to my desktop here
3:18:31if i wanted to specify a private key for
3:18:33logging in i would say ssh i and then i
3:18:36would say id rsa and then i say admin at
3:18:42192.168.1.1138 enter and typically what
3:18:45you want to do is you want to ensure
3:18:46that your private key has permissions
3:18:49you want to ensure that it can only be
3:18:51read
3:18:52by the current user and not by the group
3:18:54or all other users on the system so a
3:18:57great precaution or a great way of doing
3:18:59this is saying chmod 400
3:19:02id rsa and that will essentially protect
3:19:04your private key right so that is
3:19:07essentially how to you know set up ssh
3:19:10uh and how to copy your how to set up
3:19:13key based authentication how to copy
3:19:15your ssh keys onto the server
3:19:17and we cannot talk about you know
3:19:19copying remote files or copying you know
3:19:21files remotely with ssh so again to do
3:19:24this is very simple what i'll do is i'll
3:19:26just create a file let's say touch test
3:19:28dot ext and i'll cat fc uh password into
3:19:34the test.txt file here and what let's
3:19:37say i wanted to copy this test.txt file
3:19:40into the ssh server uh what i would do
3:19:43is i would use the scp utility so the
3:19:45scp is again secure copy so i would say
3:19:48scp and then i would specify the file so
3:19:51i'll say touch
3:19:52uh sorry test test.txt and then i would
3:19:55spare out specify the credentials so it
3:19:57say admin 192.168.1.11
3:20:00and then i'll specify the location i
3:20:02want to save it in so i say home admin
3:20:05uh this is on the remote server by the
3:20:07way so home uh i can't seem to write
3:20:09admin today for some reason and i'll
3:20:12essentially hit enter and you can see
3:20:14that it actually copied quite quickly so
3:20:17now if we try and log in so we say ssh
3:20:23one one three uh
3:20:24three and eight enter and we list the
3:20:27files within the home directory for
3:20:28admin you can see that we have the
3:20:30test.txt file and if i catch the content
3:20:33here it's the
3:20:34it's the password information for the uh
3:20:37for my client uh right over here which
3:20:39is running ubuntu and you can see my
3:20:41user accounts
3:20:42there so that is pretty much how to use
3:20:45ssh how to set it up how to set up
3:20:47authentication how to protect uh your
3:20:49root user account how to copy files
3:20:51securely how to set up key based
3:20:53authentication so i hope that was
3:20:54comprehensive enough
3:21:00so this video is going to be focused on
3:21:01essentially getting you to fully learn
3:21:04and of course utilize curl to its
3:21:07maximum potential and i'm going to be
3:21:09covering as many commands as i possibly
3:21:10can now that being said curl has a lot
3:21:13of functionality that you need to
3:21:15explore on your own as well but i'll be
3:21:17covering some of the most important bits
3:21:19of functionality that it does offer to a
3:21:21normal user or a power user as well
3:21:24so uh without any further ado let's get
3:21:26started so for those of you who have
3:21:28never heard of curl curl is essentially
3:21:30a utility that allows you to transfer
3:21:32data to or from a network server using
3:21:35one of the supported protocols now the
3:21:37protocols that it does support are http
3:21:40https ftp
3:21:42ftps you also have your sftp you have
3:21:46tftp telnet et cetera et cetera now
3:21:48there are various other
3:21:49protocols that it does support in
3:21:51addition to the ones i've just mentioned
3:21:53uh but i will get into that later
3:21:55now the great thing about curl is that
3:21:57it is a multi-platform tool which means
3:22:00uh it works on linux uh mac os and
3:22:02windows now i'm gonna be covering how to
3:22:04use it on linux but of course the
3:22:06commands are pretty much the same now in
3:22:08regards to installing uh installing curl
3:22:10it as far as i know it comes
3:22:12pre-installed with most akia linux
3:22:14distributions uh but if you want to
3:22:16install it whether or not using the
3:22:18aptitude package manager you can use the
3:22:20sudo apt-get install curl command and if
3:22:23you are if you're using an archbase
3:22:25distribution you can use the pacman s
3:22:28command to install it and the the name
3:22:30of the package is curl all right if you
3:22:32are using a mac os installation or mac
3:22:35os as your operating system you can use
3:22:37the brew install command so that is brew
3:22:40install and curl all right and that's
3:22:43pretty much uh simple right over there
3:22:44with windows you need to download an
3:22:46executable or a bin file if i'm not
3:22:48wrong and you need to save it in your
3:22:49windows directory and of course from
3:22:51that you can directly launch it from
3:22:53your command prompt
3:22:55that being said let's get started now
3:22:57curl as i mentioned comes pre-installed
3:22:59with most linux distributions so let me
3:23:01just clear the terminal here and i'll
3:23:03maximize it so we can see what's going
3:23:05on
3:23:06all right so the basic syntax is as
3:23:08follows but before we do that let's open
3:23:10up the help menu you can explore the
3:23:12help menu if you are if you're really
3:23:14looking for a bit more functionality or
3:23:16you're looking for specific functions as
3:23:19you can see it's a very comprehensive
3:23:20tool and i'm primarily going to be
3:23:22covering uh the basic commands that you
3:23:24that allow you to utilize it quite well
3:23:27uh that being said many people ask me
3:23:29how i personally learn about a command
3:23:31that or a tool that i'm not familiar
3:23:33with i personally use the man or the
3:23:36manual for each of these tools so the
3:23:38manual contains a very very good
3:23:40description of of all the bits of
3:23:42functionality in regards to a tool uh
3:23:45and all linux tools pretty much uh come
3:23:47with a manual and the manual is
3:23:49extremely useful so if you you want to
3:23:51check them out go ahead and do it i
3:23:53really really recommend it when learning
3:23:55how to uh how to use a tool
3:23:57all right so let's talk about the basic
3:23:59queries you can perform with curl all
3:24:01right so when i talk about interacting
3:24:02with the various protocols this
3:24:04particular video is going to be focused
3:24:06on http and https i know there is
3:24:09ftp functionality but i'm not going to
3:24:11be getting into that because that's more
3:24:13that's where things sort of get a bit
3:24:15different but for now let's focus on
3:24:17those two protocols all right so when
3:24:19performing a basic query of a url uh you
3:24:22essentially type in curl and then the
3:24:24url so for example if i type in
3:24:27hsploit.com here
3:24:29and hit enter what will happen is this
3:24:31will essentially fetch the content of
3:24:33the specified url so for example i've
3:24:36hit curl https hsplugged.com and it will
3:24:38essentially return to me the content of
3:24:41the entire web page now you might be
3:24:42wondering well how can we verify this
3:24:45and that's where we get into essentially
3:24:47saving your output into a file or
3:24:49downloading files so i can say for
3:24:51example curl and if i want to output the
3:24:54uh the output of this command or the
3:24:55contents of this query i can say i can
3:24:57use the lowercase o and i can then say i
3:25:00specify the directory i want to save it
3:25:02in so home alexis desktop
3:25:04and i'll just uh sorry that is desk that
3:25:07is desktop and i'll just call it uh
3:25:09hsploit
3:25:12dot html and after that i'll type in
3:25:14hsflight.com
3:25:16right over here that is the url now it's
3:25:18very important to specify
3:25:20uh the protocol that you're using so for
3:25:22example if a website is http you won't
3:25:24need to specify to get it if it is using
3:25:27the https protocol it is very important
3:25:29but i'll get into redirection in a
3:25:31second so
3:25:33https.com and we hit enter and it's
3:25:35going to give you this little status
3:25:37right over here essentially giving you
3:25:39an update as to what is the current
3:25:41status of the entire process here now
3:25:43for some reason it's taking quite a
3:25:44while now
3:25:45but we'll wait for it to complete and
3:25:47there we are so
3:25:48let me explain a bit of the uh the the
3:25:51structure of this little status menu or
3:25:54table here so for example you have the
3:25:55total amount to be downloaded uh the
3:25:58amount received the average download
3:26:00speed the upload speed the the total
3:26:03time are the time spent and the time
3:26:05left and uh right now if we cat
3:26:07uh the the hs flight dot um well
3:26:10actually if we need to go into our
3:26:12desktop here uh so if we capped
3:26:14hsploit.html here you can see the entire
3:26:16contents now if we open that up here if
3:26:19i open that up with uh with chrome for
3:26:21example let me just open this up where
3:26:23is google chrome
3:26:24um
3:26:26where is google chrome here there we are
3:26:28google chrome if i just open that up
3:26:30here in a web page you can see that
3:26:31pretty much it has all the content of my
3:26:34website so each exploit.com and it's
3:26:36pretty cool that it does save the entire
3:26:38contents of the html file here now of
3:26:40course this is going to um this is going
3:26:42to leave out
3:26:44extra bits of files in regards to the
3:26:46the web page but this is a great way of
3:26:48saving the contents of a query now that
3:26:50could be for any other protocol it not
3:26:52it does not necessarily need to be for
3:26:54the http or the https protocols all
3:26:57right now when we talk about downloading
3:26:59files
3:27:00that is pretty much how it goes for a
3:27:02web page or for a query so let me just
3:27:05remove the hsp.html mind you i could
3:27:07have saved it as a txt file i simply i'm
3:27:10saving it so that i can use it at a
3:27:12later time now you can also use curl to
3:27:15download files from the web which is
3:27:17really really awesome and that's
3:27:18primarily why i have the ubuntu page
3:27:20open here because i want an example to
3:27:22use so for example if i wanted to
3:27:23download the ubuntu iso
3:27:26i go to the download page and i select
3:27:27the air version 18.4
3:27:2918.04 lts
3:27:32and it's going to start the download so
3:27:33if i just going to show all downloads
3:27:35here and let me just copy the link here
3:27:37the download link so i can go into curl
3:27:40and i can say for example
3:27:42i can give the file name a new name or i
3:27:44can just download it directly so let me
3:27:46explain the two ways of doing it so for
3:27:48example i can say curl
3:27:50i can output the uh i cannot i can say
3:27:53download this file as ubuntu
3:27:56iso
3:27:57dot iso sorry iso and then i i paste in
3:28:01the the download link and what that is
3:28:03going to do is that it's going to
3:28:04download the file and save it as ubuntu
3:28:07iso dot iso now the extension is very
3:28:09important because if you get that wrong
3:28:11it's going to save it as a different
3:28:12file type all right so if i enter you
3:28:14can see it's going to start the download
3:28:16and there we are we can see that the
3:28:18total amount to be downloaded is one uh
3:28:19194 megabytes which is about 1.9
3:28:22gigabytes and you have the received the
3:28:24download speed the average download
3:28:26speed and the current download speed
3:28:27right over here the time left etc etc
3:28:30now you can see that my internet speed
3:28:32is pretty bad right now but that's
3:28:33primarily because i am updating one of
3:28:35my systems so i do apologize for that so
3:28:38if we check the desktop you can see we
3:28:39have the ubuntu iso over here which does
3:28:42prove that it does work all right now
3:28:44the other way of doing it
3:28:46let me just remove the ubuntu iso.iso
3:28:48file there the other way of doing it is
3:28:50by downloading it with its original file
3:28:52name which is specified on the on the
3:28:54web server so
3:28:56to do that i simply type in curl and i
3:28:58use the capital o and i paste in the
3:29:00download link and hit enter and that is
3:29:03going to download the file with its
3:29:04original download name so you can see
3:29:06ubuntu 18.04.2
3:29:08uh desktop amd 64-bit dot iso or md64
3:29:13dot iso all right so that is
3:29:15pretty much how to download files and
3:29:17now that i've explained that
3:29:19we cannot talk about redirects because
3:29:20redirects are extremely important so
3:29:23if i just get rid of ubuntu here so if a
3:29:26website is redirecting to another url
3:29:29it's very important that you know how to
3:29:31specify this to curl and why is that
3:29:33important so in many cases redirects may
3:29:36be set up and of course that is
3:29:37specified by the http
3:29:39300 request or the it could be any 300
3:29:42requests mostly theo one or three or
3:29:44three
3:29:44and it's very important that you know
3:29:47how to specify this with call now the hd
3:29:49the http protocol syntax is very
3:29:51important in curl and you can do this by
3:29:53using the l command or the capital l
3:29:55command sorry so for example
3:29:58if my website was uh if the
3:30:00urlhsflight.com
3:30:02was uh so if i say
3:30:04hsplug.com
3:30:06was redirecting to another url to
3:30:09another url and i wanted to specify this
3:30:11to curl i would use the l command now i
3:30:13know that my website is not and a great
3:30:16way of demonstrating this is by using uh
3:30:18the so for example if i say curl
3:30:21http
3:30:23hslight.com
3:30:26right over here and hit enter and we'll
3:30:28give that a few seconds here and i'll
3:30:30explain what's happening in a second so
3:30:32that you can see the importance of
3:30:33specifying uh the l parameter if there
3:30:36is a redirect so you can see i got no
3:30:38result and that's because curl is going
3:30:40to http and that's the importance of
3:30:43protocols with curl you need to specify
3:30:44the correct protocol irregardless of
3:30:46whether or not you're using ftp
3:30:48http https so my website is https now my
3:30:53website by default will redirect however
3:30:55you need to specify that with curl i do
3:30:57apologize for that and let me just clear
3:30:59the notifications here
3:31:01so again i i as i mentioned you need to
3:31:03specify this with girls so i can say
3:31:05curl and i use the l command over here
3:31:08and then i specify http
3:31:11uh and then i say hsplight.com here
3:31:13right over here and hit enter
3:31:15and that will essentially redirect me to
3:31:17the appropriate webpage and
3:31:19as you can see right over here we get
3:31:21the entire contents of the
3:31:23hsp.com website or html file rather so
3:31:26that is how to do essentially how to
3:31:29work around um how to work around
3:31:31redirects
3:31:32all right now another bit of important
3:31:35another important command sorry is the
3:31:37querying response headers so you can
3:31:39also view and analyze the response
3:31:42headers being sent by a particular web
3:31:43server
3:31:44and this can help in web assessment so
3:31:46for example if i wanted to query the
3:31:48response uh the response headers i'm
3:31:49being sent back by the web server i can
3:31:52say curl
3:31:53capital i and i can say
3:31:55https
3:31:58hs plate.com
3:32:01and i can just hit enter and what's
3:32:03going to happen here is it will give it
3:32:05a few seconds this is going to depend on
3:32:07uh varyingly depending on your on your
3:32:10particular web server so you can see it
3:32:11gives us the protocol we have cookies
3:32:13here uh we have the php version so we're
3:32:16getting important information now uh
3:32:18looks like we have some wordpress json
3:32:21files here if i delivered by the cdn or
3:32:23the content delivery network
3:32:25uh let's look at some important cookies
3:32:28here that might give us a bit of
3:32:29information in regards to the website so
3:32:30an important bit of information here and
3:32:32of course i'm using this as an example
3:32:35is the dwqa
3:32:37and this is my question and answer
3:32:39plugin that i use and you can see that
3:32:41it has an anonymous cookie that's being
3:32:42set here and that can give you
3:32:44information as to a bit more of how the
3:32:46web application is working so that is
3:32:48how to query the response that is being
3:32:50sent by the server and of course you can
3:32:51see right over here this is a cloudflare
3:32:53server and we have the cfra which is the
3:32:56cloudflare array
3:32:57that essentially uh uh
3:32:59is telling cloudflare uh what uh it's
3:33:02giving information to cloudflare about
3:33:04the particular client that is accessing
3:33:06the web server all right now that is
3:33:08very interesting however it really gets
3:33:10interesting because girl can also do a
3:33:12really cool thing it can also allow you
3:33:14to view the request headers and the
3:33:16connection details so you can view the
3:33:17tls handshake et cetera et cetera so if
3:33:20i say curl
3:33:21v and i say curl v
3:33:24https
3:33:25and they say exploit.com here and hit
3:33:27enter you can see that we can view the
3:33:29entire tls and shake which is really
3:33:32really unique and awesome so
3:33:34let me just see if i can figure uh which
3:33:37is wait which is right over here so
3:33:39there we are we can see the the initial
3:33:40connection here
3:33:42uh we i'm particularly looking for the
3:33:44tls uncheck and right over here we can
3:33:46see the tls handshake taking place so
3:33:48you can see that it is successful and
3:33:50this is a great way of identifying um
3:33:53problems with the tls uncheck if the
3:33:54certificate has an issue so for example
3:33:57we have the client hello the server
3:33:58hello we then have the encrypted
3:34:00extensions being exchanged the
3:34:02certificate is being exchanged and then
3:34:04verified and then finally the tls
3:34:06uncheck is completed you can see that we
3:34:08have the version tls version 1.3 and the
3:34:11ciphers that are being used or the
3:34:13encryption being used
3:34:14all right so you also have information
3:34:15about these certificates uh expiry date
3:34:18uh when it was actually registered uh
3:34:20the issuer all that good stuff so if you
3:34:22do want to view
3:34:24uh if you do want to view the connection
3:34:26details and a bit of an advanced
3:34:28information or additional information in
3:34:30regards to the connection you can go
3:34:32ahead and use the uh the v command
3:34:35now the last thing that i want to cover
3:34:37in regards to the http and http hts
3:34:40protocols is the fact that you can cross
3:34:42post requests and many people have seen
3:34:44me using this in ctfs particularly when
3:34:47i'm essentially brute forcing um
3:34:50login pages so
3:34:52uh i can give you an example so if i
3:34:54wanted to essentially test credentials
3:34:56on a website and this can really be in
3:34:58any uh i can be using any parameters i
3:35:01could be spoofing various cookies all
3:35:03that good stuff so for example i can say
3:35:05if i wanted to log in to wordpress site
3:35:08and i wanted to essentially test various
3:35:10credentials i can say for example
3:35:12curl
3:35:13data and that is the sorry the data that
3:35:16we're specifying and then in here i
3:35:17would specify log and this is the
3:35:19particular syntax for wordpress and the
3:35:21password would be equal to i can say
3:35:24password here and then i close the uh
3:35:27the uh the quotation marks and then i
3:35:29specify uh the wordpress page here so i
3:35:31can say
3:35:33https and you can say
3:35:36wordpress.com and i can say wordpress
3:35:39login dot php and that is the login page
3:35:43right over here and if i hit enter
3:35:45and i know this you can see that admin
3:35:47is not a valid username or wordpress.com
3:35:49etc you get the response so this is a
3:35:50great way of testing various pieces of
3:35:52data so you can also play around with
3:35:54cookies all that good stuff and in this
3:35:56case we're simply playing around with
3:35:57the login and the password parameters
3:35:59here and we specified our own values
3:36:02now if you do need to to encode the
3:36:04particular parameters you can also use
3:36:06burp suite for that so for example
3:36:09um let's see if i wanted to go um let me
3:36:12just uh turn intercept on here
3:36:15if i just went into hsploy.com here so i
3:36:18just say it it's exploit.com and it's a
3:36:20wordpress login.php
3:36:24sorry.php here and i just hit enter and
3:36:27uh for some reason we're getting stack
3:36:29uh stack
3:36:30we're just getting a stack protect here
3:36:32in any case uh the what i was getting to
3:36:34if you do want to encrypt your url or
3:36:36any other parameters you can use the
3:36:38control plus u key
3:36:43in this video we're going to be looking
3:36:45at how to use the uncomplicated firewall
3:36:48or as it is commonly known as ufw on
3:36:51linux alright so you might be asking
3:36:53what exactly is ufw or what is the
3:36:56uncomplicated firewall if it isn't
3:36:58already self-explanatory well
3:37:01ufw or the uncomplicated firewall acts
3:37:04as an interface to ip tables and is
3:37:06designed to simplify the process of
3:37:09configuring a firewall now you also
3:37:11might be asking well what exactly is
3:37:13iptables well iptables is an extremely
3:37:16flexible firewall utility that was built
3:37:19for linux operating systems now you also
3:37:21might be asking well why aren't we using
3:37:24ip tables why are we using ufw as
3:37:26opposed to ip tables well iptables is a
3:37:29great tool that offers great
3:37:30functionality when it comes down to
3:37:32configuring firewalls however it can be
3:37:34difficult for beginners to learn how to
3:37:36use it properly when configuring a
3:37:38firewall as a result ufw is well suited
3:37:42for beginners and as a result they can
3:37:44use they can learn how to use a firewall
3:37:46or to configure a firewall really really
3:37:48easily and they can learn about rules
3:37:50etc they get the the general idea behind
3:37:53a firewall all right so ufw is a is a
3:37:57great firewall that is designed to be
3:37:59run on hosts or servers uh but it's only
3:38:02doubtful in the extent is in the extent
3:38:04uh it offers in in terms or in regards
3:38:07to functionality what i mean by this it
3:38:10it only goes so far as uh
3:38:13as allowing you to block or allow
3:38:15connections to and from uh to and from
3:38:17the server so incoming and outgoing and
3:38:19you can also block ip addresses ports
3:38:21etc and entire an entire subnet
3:38:24which i'll get into in a second
3:38:26all right
3:38:28so the purpose of this video the purpose
3:38:30of this video is to teach you how to use
3:38:31ufw and all the comments that you need
3:38:33to know to get started and to fully
3:38:35utilize it to its uh due to your
3:38:38advantage really so this will include
3:38:39commands such as allowing and blocking
3:38:41various services by port uh and their
3:38:44source ip addresses and this video
3:38:46should be used as a reference so if this
3:38:48is your first time with ufw you can
3:38:50definitely find something that you
3:38:51haven't you that you didn't know in this
3:38:53video if this is your if you're already
3:38:55an experienced use of ufw hopefully you
3:38:57can find something in this video that
3:38:59you didn't know already alright so
3:39:01without any further ado let's get
3:39:03started
3:39:04so
3:39:05uh installing ufw is very very simple
3:39:08now if you are using an ubuntu server or
3:39:10you're running ubuntu ufw should be
3:39:12pre-installed on it if it isn't getting
3:39:14installed on any other distribution is
3:39:16very very simple use your aptitude
3:39:18package manager so sudo apt-get install
3:39:22ufw i already have mine installed so
3:39:24it'll check for an update if there isn't
3:39:26an update it's not going to update it
3:39:28and it's going to give me the results
3:39:29here all right so once it is installed
3:39:31we are ready to begin
3:39:33now the important bits of using ufw are
3:39:36always knowing its state or its status
3:39:38all right so currently i have ufw
3:39:41disabled it is not running and if i
3:39:43wanted to know that i would simply type
3:39:45in
3:39:46sudo
3:39:47ufw status now it is very important to
3:39:50precede the ufw command with sudo if
3:39:53you're not using a root user in my case
3:39:55i'm using the root user so i don't need
3:39:58to use the sudo command but in any case
3:40:00i will use it so that it becomes a good
3:40:02practice with you and i don't recommend
3:40:05running efw from the root user but this
3:40:07is a simple video for demonstration all
3:40:10right so i'm going to hit enter it's
3:40:11going to tell you the status of the ufw
3:40:14or the uncomplicated firewall is
3:40:16inactive which is great all right now i
3:40:19can also check an additional i can get
3:40:21more information from the status command
3:40:23by typing in verbose which will give me
3:40:25more information in regards to the rules
3:40:27that are currently active now as you
3:40:29guessed it will not display anything
3:40:31because we haven't set any particular
3:40:33rules and the if the firewall is
3:40:35currently not active so nothing really
3:40:38special there and the last status
3:40:40command that is very very popular is to
3:40:42is to show the status the numbered
3:40:44status so that you have an idea of what
3:40:46uh what rules are currently running and
3:40:48their number so that you can terminate
3:40:50or delete them all right so that's what
3:40:52what it's there for now of course these
3:40:54don't make any sense right now because
3:40:56the the current status of the firewall
3:40:58is inactive once we activate it or once
3:41:01it is active we will be able to get a
3:41:03whole lot more information from them all
3:41:05right so i'm going to enter again you'll
3:41:06see it's going to tell you that it is
3:41:08inactive and that is fine
3:41:10all right
3:41:11so let's talk about enabling disabling
3:41:14and resetting ufw so enabling ufw is
3:41:16very simple sudo ufw and enable and that
3:41:20will enable the firewall and it'll give
3:41:22you the little status over here the
3:41:24firewall is active and is enabled on
3:41:27system startup which is excellent so
3:41:28that it is always active and if you are
3:41:30running a server that is huge for you
3:41:33all right so disabling it is very very
3:41:35simple we simply type in
3:41:37disable and we hit enter
3:41:40all right and that will tell you that
3:41:41the firewall is stopped and disabled on
3:41:43on system startup
3:41:45now when i talk about resetting the the
3:41:47ufw or the uncomplicated firewall this
3:41:50is in regards to the rules that you
3:41:51might have set now please do use caution
3:41:54with the reset command the reset command
3:41:56is there to to help you out if you have
3:41:58made a mistake in configuring your
3:42:00firewall now if you already have a
3:42:01working firewall and you only want to
3:42:03delete a particular rule do not use the
3:42:05reset command because that will reset
3:42:08your firewall to the default uh to the
3:42:10default configuration that it came with
3:42:12pre-installed or installed or the the
3:42:14configuration it came with installed all
3:42:16right so if i type in sudo ufw
3:42:20uh ufw reset that will reset it and
3:42:22it'll tell you that which is very good
3:42:24resetting all the rules to the installed
3:42:26defaults proceed with operation
3:42:29y or n for yes or no hit yes to reset it
3:42:33and there you are so there is a small
3:42:35fyi if in case you wanted to know that
3:42:37and you've messed up
3:42:38in this video and you want to reset it
3:42:40there you are
3:42:41all right so what we're going to do is
3:42:42we're going to start off we
3:42:44understanding the default policies uh
3:42:46for the ufw or the uncomplicated
3:42:49firewall
3:42:50all right so
3:42:52uh the default policies uh for ufw are
3:42:56as follows uh now before we do that let
3:42:59me explain something so ufw
3:43:01uh by default will it will deny all
3:43:04incoming connections but will allow all
3:43:06outgoing connections so what is
3:43:08happening here is sudo ufw
3:43:11and you can you can always use this to
3:43:13to restore it to its default policies so
3:43:16sudo ufw
3:43:18default
3:43:20deny
3:43:21incoming
3:43:23all right so that is the default uh that
3:43:25is the default connection for incoming
3:43:27or the default connection status for all
3:43:29incoming connections so by default ufw
3:43:32will deny all incoming connections and
3:43:34it will
3:43:35it will allow
3:43:37all outgoing connections
3:43:41so it will allow all default outgoing
3:43:43connections and of course you can change
3:43:45this to whatever you want if you want
3:43:47incoming connections to be allowed while
3:43:49the firewall is active then you can also
3:43:51do that as well so i can say default
3:43:53allow
3:43:54incoming all right which is not the
3:43:57smartest thing to do if you're running
3:43:58this on a server you want to manage what
3:44:01connections are incoming
3:44:02in case your your server is being
3:44:04attacked but that is a very very
3:44:05different story and hopefully i'll make
3:44:08a video on that later on in configuring
3:44:10a server for security
3:44:12in this case we'll just leave them to
3:44:14its defaults all right which are are
3:44:16going to be set by default you don't
3:44:17need to set them i'm simply explaining
3:44:19to you how to do it and how to change
3:44:21them if you want to change them all
3:44:22right so this gate is great for normal
3:44:24systems uh but when it comes down to
3:44:27servers it becomes a little bit
3:44:28different and you want to be able to
3:44:30manage the incoming connections in
3:44:33regards to services and ports and the ip
3:44:35addresses that are going to be allowed
3:44:37to connect to your computer or your
3:44:39server
3:44:40all right
3:44:41so what i want to do is
3:44:43the first thing i want to do is i'm
3:44:44going to talk to talk about services and
3:44:46ips all right so if i want to allow an
3:44:49incoming ssh connection uh how do i do
3:44:52that well it's very simple so sudo ufw
3:44:56allow ssh all right and this is going to
3:44:58allow all ssh connections it's going to
3:45:00allow in incoming ssh connections all
3:45:03right which is okay if
3:45:05as long as you have a private key and
3:45:07you've properly secured the ssh
3:45:09connection and and the authentication
3:45:12all right so i'm going to hit enter it's
3:45:13going to tell me rule is updated
3:45:15fantastic you can also do this by typing
3:45:17in the port so i can say sudo ufw allow
3:45:2122 and it's going to update uh the rules
3:45:24accordingly now if i want to if i want
3:45:26to disable you ssh incoming ssh i can
3:45:29say sudo ufw deny
3:45:32ssh all right and i'm going to hit enter
3:45:34it's going to tell me the rule is
3:45:35updated which is which is also very very
3:45:37good and of course you can do that
3:45:39with the port as well but with services
3:45:42these are the particular services the
3:45:44services by the name in which they are
3:45:46sorted so ssh is going to be known as
3:45:48ssh and it knows that ssh uses port 22.
3:45:52all right let's talk about uh working
3:45:53with port 80 or http connections
3:45:56so that is what uh unencrypted web
3:45:59servers use and the connections can be
3:46:01allowed with the following command so
3:46:03you can type in sudo ufw
3:46:05uh allow
3:46:07allow http and we hit enter it's going
3:46:10to update the rules and you can also do
3:46:12it with using uh you can also do it
3:46:14using the port which is port 80 hit
3:46:16enter and there you are in my case i'm
3:46:18going to deny this so i'm going to say
3:46:20deny http hit enter and we're good again
3:46:23all right so what i'm going to do is
3:46:26before we actually continue i'm going to
3:46:27leave some services running so that when
3:46:29i enable the firewall you'll be able to
3:46:31see them when i when i essentially check
3:46:33the status
3:46:34all right so i'm going to say
3:46:37ufw
3:46:38enable or sorry allow
3:46:41allow ssh because i want to allow ssh
3:46:44connections
3:46:45sorry about that my typing is pretty bad
3:46:47right now allow ssh there we are
3:46:49fantastic and we can move on to the next
3:46:51protocols and services
3:46:53now talking about https or port 443 that
3:46:56is again uh what encrypted web servers
3:46:58use and can be allowed with the
3:46:59following command so you can type in
3:47:01sudo
3:47:03allow https and hit enter and that's
3:47:06going to allow https connections again
3:47:08that can be replicated or duplicated
3:47:10with the port 443 in this case i'm just
3:47:13going to deny the connection so i'm just
3:47:16going to https and there we are so the
3:47:18rules are going to be updated
3:47:19successfully for ipv4 and ipv6 as well
3:47:22that is why you have rules updated for
3:47:24both the protocols over here
3:47:26all right now if you want to allow both
3:47:28uh http and https you can do that in
3:47:32you can do it in one command and that is
3:47:33done by typing sudo ufw allow and you
3:47:37can also deny it as well so proto the
3:47:39protocol is going to be tcp
3:47:42proto is tcp you can also change that
3:47:44depending on what protocol you're using
3:47:45so from any
3:47:47from any target or you can also use the
3:47:50ip so from this particular target but
3:47:53i'll get to that in a second so we're
3:47:54going to say from any any computer we
3:47:56are simply going to allow the connection
3:47:59from any
3:48:00to any
3:48:02port
3:48:03uh to any port and we specify the port
3:48:06support 80 and 443 hit enter the rules
3:48:09updated so we can also deny it as well
3:48:11which is what i'm gonna do because i
3:48:12don't want that running so deny and
3:48:15voila all right so that is how to run it
3:48:17in one command and the the key words
3:48:19here are going to be the allow and deny
3:48:22that is the most important bit here all
3:48:24right if you're talking about ftp that
3:48:26is again uftp uh sorry um
3:48:28uh ufw nor am i talking ufw
3:48:32uh ufw allow ftp or port 21
3:48:36and that can also be denoted by port 21
3:48:39tcp hit enter and it's going to uh
3:48:42because it already exists we can then
3:48:44say deny
3:48:46and you need to specify with ftp that
3:48:48we're using it in tcp so deny rules
3:48:51updated successfully and that is how to
3:48:53configure or enable and disable ftp
3:48:55connections
3:48:56all right now let's move on to ip
3:48:58addresses now before we actually move on
3:49:01to ip addresses four services this is
3:49:03all done through the port and also
3:49:05through the name so if you're running
3:49:06pop3 a pop3 mail server you can also do
3:49:09it as well if you're running mysql i can
3:49:11say ufw
3:49:12allow
3:49:143306 that is a mysql a database and i'm
3:49:17just going to deny it or i'll leave that
3:49:19running so that we can also check the
3:49:20status i don't have a mysql server
3:49:23running on this computer but that's how
3:49:25you one would do it so uh in most cases
3:49:27you want to deny connections to your ad
3:49:30to your
3:49:31to your mysql database so in this case
3:49:33i'm going to say 3306 deny any
3:49:35connections to that particular port and
3:49:37of course i can specify the eyepiece
3:49:39with my previous command that i showed
3:49:41you right over here so i can say ufw
3:49:43deny protocol tcp
3:49:45from any to uh
3:49:47from any to any port and then specify
3:49:493306 here hit enter the rules are going
3:49:52to be updated so we can deny all
3:49:54connections to our sql database which is
3:49:57hugely important that's why you have
3:49:59open databases running and available to
3:50:01be accessed publicly on show then they
3:50:04can simply be exposed so this is one of
3:50:05the things you must do on your firewall
3:50:08all right so getting back to ip
3:50:10addresses again it's very very simple so
3:50:12if i want to allow incoming connections
3:50:13from a particular ip address i can
3:50:15simply type in ufw
3:50:17allow and i type in uh the ips so allow
3:50:20from
3:50:22192.168.1.1 which is my gateway or
3:50:24access point iep address which is
3:50:26important because if i don't allow
3:50:27incoming connections from it
3:50:30i essentially won't be able to to get
3:50:32any internet access so i'm going to hit
3:50:33allow which is important
3:50:37and and that's very very important as i
3:50:39mentioned when your firewall is active
3:50:41because if you want to allow incoming
3:50:42connections you need to specify what ip
3:50:44or what ip subnet they may belonging to
3:50:47so uh what an example i can give you
3:50:50here is if you want to specify a
3:50:51particular port uh for a particular ip
3:50:54address for example i i only want the ip
3:50:58address
3:50:59192.168.1.103 to access ssh i can type
3:51:02in the following so i say sudo ufw
3:51:06allow from 192.168.1.103
3:51:10to any port
3:51:12to any port 22. so this will only allow
3:51:15uh this particular ip address to access
3:51:18the as this the ssh service i'm going to
3:51:20enter it's going to say rules are
3:51:22updated now if you're wondering what uh
3:51:24the ip address 192.168.1.103
3:51:27is my windows operating system and i
3:51:30usually connect to my cali operating
3:51:31system to it remotely via uh via putty
3:51:35all right so that is a good rule to have
3:51:38uh when talking about subnets it's very
3:51:39very simple again so sudo ufw uh allow
3:51:44from and we specify the subnet range
3:51:46here 182.968.1.1
3:51:49uh and 24 but i don't want to do that
3:51:51because i only want particular ip
3:51:53addresses
3:51:54uh to essentially uh to be allowed in
3:51:57regards to incoming connections so i'm
3:51:58gonna i'm not gonna hit enter but that
3:52:00is how to specify a particular subnet
3:52:03you can also disable or deny a
3:52:05particular connections
3:52:06all right so
3:52:08we have already talked about denying uh
3:52:10access and again it is all in regards to
3:52:13what you want to do in regards to the ip
3:52:15so what i can say for example if i
3:52:17wanted to allow a particular subnet
3:52:19to access the mysql database i can say
3:52:22for example
3:52:24sudo
3:52:25ufw
3:52:26allow
3:52:28from
3:52:29192.68.1.1.1
3:52:33and 24 and to any
3:52:37any port
3:52:39i can say any port
3:52:413306 of course that is a very stupid
3:52:44thing to do so i'll just keep it to port
3:52:4622 with this which is ssh so all of my
3:52:48computers in my subnet should be able to
3:52:50access this computer via the ssh port
3:52:53only i'm going to hit enter and it's
3:52:55going to tell me rule change after
3:52:56normalization because we already had it
3:52:58active so it is changed and updated the
3:53:01rule
3:53:02all right so let's talk about deleting
3:53:03rules because that is essentially as far
3:53:05as it will go in regards to allowing in
3:53:07denying rules to uh incoming and
3:53:10outgoing connections
3:53:11to and from your firewall so we've
3:53:13looked at allowing and denying ports
3:53:15services and ip addresses let's talk
3:53:17about deleting particular rules so now
3:53:19that we've set our rules we can
3:53:21essentially enable the firewall now so
3:53:23i'm going to say sudo
3:53:25sorry about that sudo
3:53:28sudo enable and we type in uh sudo ufw
3:53:32enable sorry about that
3:53:33ufw enable i was getting a bit confused
3:53:36there with ip tables you have w enable
3:53:38and that's going to enable the firewall
3:53:41excellent so now we can check the status
3:53:43all right so the status as i mentioned
3:53:44is very very simple to check uh which by
3:53:47the way is going to include the number
3:53:48status so the default status is sudo ufw
3:53:53status
3:53:54gonna hit enter and it's gonna give you
3:53:56the current status of the firewall all
3:53:58right so
3:53:59tcp
3:54:00is going to be allowed which is port 22
3:54:02which is as it is going to be allowed
3:54:05which is incoming
3:54:07it's going to allow
3:54:08tcp our weight we have port 80 deny
3:54:11allow for for it again so incoming
3:54:14outgoing uh the same goes for what we
3:54:17had set for um
3:54:20the rule set for both
3:54:22uh http and https we had set our ftp
3:54:25rule set here we'd set our mysql
3:54:28database rule set here to deny
3:54:31again we had set it
3:54:33via tcp remember it's very important to
3:54:35specify the protocol
3:54:37uh we then have again we set the rules
3:54:39to now a particular iep address remember
3:54:42from here they were all from anywhere or
3:54:44any particular source
3:54:45so allow all connections coming from
3:54:48my access point uh allow all ssh
3:54:51connections in coming from this
3:54:53particular ip
3:54:54allow any incoming ssh connections from
3:54:57any particular ip in this subnet which i
3:54:59set incorrectly it should have been one
3:55:01not zero that's my primary
3:55:03uh access point that is sitting outside
3:55:05of my office
3:55:07and then we have all the all these
3:55:09settings for uh for the ipv
3:55:12ipv6 protocol so that is how to check
3:55:14the status now you want to display a bit
3:55:16more information we use the verbose
3:55:17command
3:55:18verbose over here and i'll give you a
3:55:20bit more information and this is
3:55:22primarily what i like using
3:55:24so this is the status that i like using
3:55:27the verbose status because it tells you
3:55:29the status is active logging is on on
3:55:31low
3:55:32the default policies are to deny
3:55:34incoming and allow outgoing as i
3:55:36mentioned
3:55:37and now we have for
3:55:39for port 22 under the protocol tcp we
3:55:42want to allow incoming connections we
3:55:44want to allow incoming connections there
3:55:46which we is not clever but anyway we had
3:55:49set it to any computer on this subnet so
3:55:51that makes sense
3:55:52we want to deny incoming http
3:55:54connections we want to allow then
3:55:56incoming http connection and that's
3:55:58because i was actually showing you that
3:55:59we can actually disable it so
3:56:01i can say ufw
3:56:04we can say d9
3:56:06for 80
3:56:07and it's going to update it and we hit
3:56:09enter and there we are so now it's it's
3:56:11where we're simply denying the rules
3:56:12here which is great all right so deny
3:56:15deny for both port 80 which is http uh
3:56:18for https we are also denying and that's
3:56:21simply giving you the the action so
3:56:23we're denying or allowing in connections
3:56:26and the only ones being allowed inside
3:56:28are going to be for the ssh port right
3:56:31over here and right over here which are
3:56:34going to simply be allowing particular
3:56:36ip addresses
3:56:38and the entire subnet and all ip
3:56:40addresses from the connection now you
3:56:41might want to change this if you want to
3:56:43only specify a particular subnet
3:56:46but that's simply how to check the
3:56:48verbose status now if you want to look
3:56:50at the numbered status which is
3:56:51important because you might want to
3:56:52delete a particular rule you do that by
3:56:55typing sudo ufw status numbered
3:56:57[Applause]
3:56:59status numbered
3:57:01like so and we hit enter and that is
3:57:03going to number all of the rules that
3:57:05you had set which is very important if
3:57:06you want to delete a particular rule all
3:57:08right so let's take a look at how to
3:57:10delete a particular rule so if i wanted
3:57:12to delete um
3:57:14i want to delete
3:57:16rule 1 and 2 i can do that so i can type
3:57:18in sudo ufw delete
3:57:22and i simply type in one for example and
3:57:24that is going to ask me do i want to
3:57:25delete this particular rule i'm going to
3:57:27hit yes and then i'm going to i want to
3:57:29delete rule 2 as well and yes and if we
3:57:32check the these these status the verbose
3:57:35status here we can see yes now we are
3:57:38talking now we have uh we we have
3:57:40correctly set up our our firewall here
3:57:42so it's going to allow
3:57:44uh allow in connections we can also get
3:57:46rid of that one as well so we're going
3:57:48to simply display the status here the
3:57:50number status so let's get rid of 1 as
3:57:52well
3:57:541 here yes we want to get rid of that
3:57:57and we showed the status once more
3:58:00we can see that yes we are denying all
3:58:02connections all http connections all
3:58:05https connections and we also set this
3:58:08rule which is a duplicate rule of both
3:58:09these two so i'm showing you how to do
3:58:11it really shortly uh we are denying ftp
3:58:13we are denying uh mysql access
3:58:17via tcp and also the the port whether it
3:58:19be on tcp or udp irregardless the only
3:58:22ones we're allowing inside are going to
3:58:24be connections coming from this
3:58:26particular ip which is the access point
3:58:29and this particular ip which is my
3:58:30windows operating system and that is
3:58:32going to be going to be allowed on port
3:58:3322
3:58:35uh and the entire subnet is going to be
3:58:37allowed on port 22 which is really
3:58:39redundant because i should have just
3:58:40gotten rid of this one right over here
3:58:42but regardless that is how to delete uh
3:58:45the particular rules and if you want to
3:58:46reset it again resetting it is very very
3:58:48simple to take it back to the defaults
3:58:50that if is if you have messed up your
3:58:53rule set and you want to just start over
3:58:55fresh so sudo
3:58:57ufw
3:58:59reset and we hit enter it's going to ask
3:59:01you yes
3:59:02and remember the firewall is still
3:59:04active so if i just check the status
3:59:06it's going to tell us that it is
3:59:08inactive that's because we reset it so
3:59:10uh if we we uh we enable it so ufw
3:59:14enable
3:59:16and uh we'll then check the status right
3:59:19now we have or we don't have any rule
3:59:21set so that is how to use ufw or the
3:59:24uncomplicated firewall to allow incoming
3:59:26and outgoing connections to ports
3:59:29from ip addresses particular ip
3:59:30addresses their services how to delete
3:59:33particular rules and how to monitor the
3:59:35current rules that you have set up so
3:59:37that is pretty much all you need to know
3:59:38in regards to getting started and and
3:59:40fully utilizing ufw you know in in
3:59:43regards to configuring a particular
3:59:44operating system or a server if that's
3:59:46what you're working with so
3:59:52in this video i'll be showing you how to
3:59:53clear your tracks on linux operating
3:59:55systems with a variety of tools all
3:59:58right so why is this important now if
4:00:00you're a penetration tester you probably
4:00:02already know why this is important well
4:00:04covering tracks or clearing your tracks
4:00:06is the final stage of penetration of the
4:00:08penetration testing process so just
4:00:10before you start report writing and that
4:00:12video is on its way by the way so do
4:00:15stay tuned for that so clearing your
4:00:17tracks essentially involves clearing or
4:00:19wiping all the activity of an attacker
4:00:21or you being the attacker that is so as
4:00:24to avoid any detection by incident
4:00:26response teams or forensic teams all
4:00:29right so it is vitally important in the
4:00:31penetration testing life cycle
4:00:33and of course if you look at it from a
4:00:35defensive point of view it can really
4:00:37test incident handlers and the blue team
4:00:39in their ability to discover an attacker
4:00:42in in the system whether they do have an
4:00:45intrusion detection detection system or
4:00:47not and of course from the perspective
4:00:49of the forensics teams it can also test
4:00:52them in uh sort of analyzing their skill
4:00:54and finding what the attack the attacker
4:00:56may have left behind in regards to logs
4:00:59uh files or backdoors that they may have
4:01:01left running any user accounts that they
4:01:03were using etc so this is usually or
4:01:06commonly the biggest mistake vector that
4:01:08an attacker makes all right or that is
4:01:10associated with with attackers and it's
4:01:12something that has been ignored over the
4:01:14years which is really really weird
4:01:15because if you read or pick up any
4:01:16penetration testing book
4:01:18when they essentially explain the
4:01:20penetration testing
4:01:22cycle or the stages of penetration
4:01:24testing uh clearing your tracks is one
4:01:26of them just before you actually write
4:01:28up your report and of course if you're
4:01:30an attacker this is the final stage of
4:01:33uh of your attack and of course leaving
4:01:34some persistence behind but that's
4:01:36another video for another time
4:01:39so
4:01:39it's it's very very sad to see that this
4:01:41is not taken into consideration i'm not
4:01:43talking about this from an attacker's
4:01:45perspective but also from a blue team
4:01:47perspective where uh this is something
4:01:49that is very easy for them because
4:01:51attackers are very very sloppy they they
4:01:53haven't taken it into consideration so
4:01:56it's really good to essentially
4:01:57understand how this is done and how it
4:01:59can be
4:02:00and how it can be analyzed from both
4:02:02perspectives from a red team and a blue
4:02:04team perspective so
4:02:05uh this is usually as i've said the
4:02:07biggest mistake of an attacker and this
4:02:09is where the professional attackers are
4:02:11sorted out from the amateurs so if you
4:02:13take a look at most of the biggest hacks
4:02:15in the world over the last two years
4:02:17most of the the detection has been made
4:02:19really really easily from the malware
4:02:21that they have left behind which they
4:02:23didn't clear they should have cleared
4:02:24but of course they were setting it up
4:02:26for persistence as i said that's a video
4:02:29for another time but again also masking
4:02:31malware or backdoors is also a vital or
4:02:34an important piece of uh of the forensic
4:02:37or well not the forensic the post
4:02:38exploitation
4:02:40all right now when we talk about uh the
4:02:42attacker's perspective uh he or she
4:02:45usually needs to
4:02:46evade detection if there is an intrusion
4:02:48detection system therefore preventing
4:02:50any incident response and then he or she
4:02:53needs to clear the logs or back doors
4:02:55that can be discovered by the forensics
4:02:57team all right so what an attacker is
4:02:59looking to do and should do is first of
4:03:02all clear logs modify registries or
4:03:05clear any of the registries that they
4:03:07did create and lastly remove any files
4:03:10or user accounts that they might have
4:03:11been using all right now as i've said
4:03:14for this particular video we'll be
4:03:15focusing on linux i also want to make an
4:03:17independent video for windows because it
4:03:19is vitally important to understand how
4:03:21to do so on both these operating systems
4:03:24and also probably take a look at mac os
4:03:27as that is also getting quite uh quite
4:03:29popular especially for penetration
4:03:31testers
4:03:32so i'm going to be covering the
4:03:33fundamentals and you can do a lot of
4:03:35your own research i'll be covering the
4:03:36tools that i've personally used before
4:03:40and
4:03:41really uh the last piece that i want to
4:03:43actually tell you is clearing your
4:03:44tracks will also depend on the
4:03:46privileges that you have on the system
4:03:49and whether or not you're remotely
4:03:50attacking the system but for linux it is
4:03:52quite universal
4:03:54all right now i also have a little or a
4:03:56quick tool that i'll be sharing with you
4:03:57at the end of the video that is an a
4:03:59forensics tool or an anti-forensics tool
4:04:01for windows so you can definitely check
4:04:03that out
4:04:04i'll probably make another video of it
4:04:05but for now let's focus on linux all
4:04:07right so let's talk about the linux log
4:04:10files which are the most important
4:04:11aspects
4:04:12uh of uh of persistence or activity that
4:04:15is being logged on the linux operating
4:04:17system or the linux kernel
4:04:19all right so your the log files on any
4:04:21linux system can be found on in the var
4:04:25well actually let me just change
4:04:26directory into that so cd var and it is
4:04:29stored in the log directory right over
4:04:31here so now that i'm in the directory i
4:04:33can list all the files in here
4:04:35and these are all the log files that
4:04:37currently exist and of course if you
4:04:39just read their name they're pretty
4:04:40self-explanatory they have all they they
4:04:43have they're all they all have their
4:04:45various use cases and what data they are
4:04:48essentially logging all right so for
4:04:50example when talking about uh the
4:04:52auth.log file this stores authentication
4:04:55logs uh let's see if
4:04:57let's see if we can find the kernel if
4:04:59we can find yet there we are the
4:05:00kernel.log file which essentially stores
4:05:03all the kernel logs you then have the
4:05:05mail server logs which is of course uh i
4:05:08don't think we have a mail server here
4:05:09but if we did you'd have the mail server
4:05:12logs as well you then have the system
4:05:14bootlog which is your boot your boot log
4:05:16which again we don't have here for some
4:05:18reason
4:05:20we then have um
4:05:22you have your http the httpd log which
4:05:25essentially has logs for your web server
4:05:27if you do have a web server
4:05:29or a web server that being the apache
4:05:31web server so again there are a lot of
4:05:33log files here we're going to be
4:05:34focusing on the auth log right of you
4:05:37which essentially contains the
4:05:38authentication logs and then we'll take
4:05:40a look at the bash history file which is
4:05:43very important as well we'll also take a
4:05:44look at the shred file as well so
4:05:47let's talk about the shred file and the
4:05:50the the auth dot log file
4:05:52all right so if i'm just to open up the
4:05:54auth.log file here this essentially
4:05:56stores all the uh the authentication
4:05:59logs which are very very important for
4:06:01to a forensics team uh to essentially
4:06:03analyze what was happening to the system
4:06:05what activities were carried out etc etc
4:06:09all right so you can go ahead and
4:06:10analyze all all of the files right over
4:06:13here and get an idea of of essentially
4:06:16uh what was going on and of course that
4:06:18is uh
4:06:19that deserves its own video in its own
4:06:22right because that is more of a
4:06:23forensics type of video
4:06:25but for now we're looking to get rid of
4:06:27this because remember if you're an
4:06:28attacker you want to get rid of all of
4:06:30these files so that uh they really
4:06:32cannot build an idea of what was going
4:06:34on on the system all right so let me
4:06:37just exit out of this and as i said the
4:06:40tool that is most recommended for any of
4:06:42this getting erasing files erasing hard
4:06:45drives is shred now if you haven't heard
4:06:47of shred shred is essentially a tool
4:06:49that allows you to delete uh or erase a
4:06:52file permanently so it allows you to
4:06:54delete files data permanently now many
4:06:57of you might be confused with saying wow
4:06:58why can't you just delete it well if you
4:07:00delete a file
4:07:02it can be recovered and i'll explain
4:07:03this in a second so shred allows you to
4:07:06delete files and data permanently and
4:07:07prevents the recovery of that data
4:07:10it does this because it over it
4:07:12overwrites the file multiple times with
4:07:14ones and zeros now when you
4:07:16traditionally delete a file with your
4:07:19graphical user interface or you simply
4:07:21hit the delete a key on your keyboard
4:07:23what's happening here
4:07:25is your file isn't being deleted it is
4:07:27simply marked as a space in which data
4:07:30can be written to or data can be written
4:07:32on top of therefore replacing the
4:07:34previous data and of course this is
4:07:35going to be dependent on how you use the
4:07:37computer and that's why when you you see
4:07:39these real amateurs are doing
4:07:41questionable things on their computer
4:07:43you know doing illegal stuff on the
4:07:44computer
4:07:46just delete the file without even
4:07:48realizing that you aren't deleting it is
4:07:50deleted for you the user but uh in the
4:07:53back end the file still exists it's
4:07:55simply marked that the sector is simply
4:07:57marked as a as a space that should be
4:08:01written onto us and when it's written
4:08:03onto then the files are lost but you can
4:08:05still perform a lot of data recovery
4:08:07that's why you have an industry
4:08:09dedicated to data recovery because of
4:08:11how operating systems are and how they
4:08:13uh they essentially mark spaces or data
4:08:16that you won't delete it there's spaces
4:08:17that can be overwritten all right so
4:08:19that is the difference between keeping
4:08:21files and maintaining uh the fact that
4:08:23they cannot be written to
4:08:25or overwritten that is
4:08:27by other files and and
4:08:29when you actually hit delete so when we
4:08:32talk about a tool like shred shred is a
4:08:34tool that i've used a lot of times
4:08:36before for wiping or erasing hard drives
4:08:39when i'm when i'm done with them when
4:08:41i'm disposing them or when i'm selling
4:08:42drives which is very very rare never
4:08:45sell your drives
4:08:47all right so shred comes pre-installed
4:08:49in kali linux and i'm guessing in pretty
4:08:50much all the other distributions so i'm
4:08:53just going to clear this out and what
4:08:54we're going to do is we're just going to
4:08:56open up shred here with the help command
4:08:59and the shred tool is quite
4:09:01comprehensive and i'll try and explain
4:09:03all the commands
4:09:04all right so the shred command
4:09:06essentially when you when you're writing
4:09:08to a file or a particular drive it uh
4:09:11it essentially overwrites the specified
4:09:14files repeatedly and therefore making it
4:09:16difficult or impossible for uh you know
4:09:19hardware software or software recovery
4:09:21to to get the data back all right so the
4:09:24options or the parameters that you can
4:09:25specify
4:09:26with the shred tool are as follows you
4:09:28have the f the f command which
4:09:30essentially allows you to change
4:09:32permissions to allow writing if needed
4:09:34you have the n command which is the
4:09:35iterations or essentially this allows
4:09:38you to overwrite the amount of times you
4:09:40want which is which is good the default
4:09:42amount of times is three which is okay
4:09:44but if you're really paranoid about you
4:09:46know about your files and you really
4:09:48want to get rid of them you can increase
4:09:50the amount of times all the iterations
4:09:52then have the size uh the size of the
4:09:54number of bytes to shred you then have
4:09:56the u command which is essentially
4:09:58allows you to
4:09:59uh to truncate uh it essentially
4:10:01truncates and remove the files after
4:10:03overwriting you then have the v command
4:10:05over here which shows your progress over
4:10:07both uh shows verbose information about
4:10:09the progress you then have the x command
4:10:12right over here which essentially
4:10:14uh this what this does is again is it's
4:10:17self-explanatory but this does not round
4:10:19the files up to the next full block
4:10:22uh we then have the z command which adds
4:10:24the final overwrite with zeros to hide
4:10:26shredding so it uh usually with uh
4:10:29with software recovery tools they can
4:10:31actually detect if there was shredding
4:10:33done and this prevents that and you have
4:10:35u the u command which essentially
4:10:37removes the file after threading which
4:10:39is what we're going to be taking a look
4:10:40at as well
4:10:42all right so let's take a look at the
4:10:43command that we'll be using and i'll
4:10:45explain what's going on
4:10:47all right so we'll be using the vfzu
4:10:49command which if we just look at the
4:10:51arguments here we are going to be using
4:10:53the v so verbose v
4:10:55f z u so f we're going to force to
4:10:58change the permissions if they exist so
4:11:00if you don't have read and write
4:11:01permissions is going to force it
4:11:03uh so uh there we are so z uh we're
4:11:06going to use the v f z u so then z is
4:11:09going to be essentially add a final
4:11:10override with zeros to hide the
4:11:12shredding process which is good and we
4:11:14are going to remove the file uh after or
4:11:17after the overwriting process all right
4:11:19so that is what is going on here so to
4:11:21do that we simply type in shred
4:11:24and after shred we type in our commands
4:11:26or the combination of commands so
4:11:28vfzu and the file which is auth.log and
4:11:32i'm going to hit enter and there we are
4:11:34all right so shred it's going to start
4:11:36the shredding process right over here
4:11:37and you can see shred uh authored logo
4:11:40was renamed to zero zero zero et cetera
4:11:42renamed renamed renamed all the way to
4:11:44uh to the fact that the file was removed
4:11:47or destroyed all right so that gets rid
4:11:49of the auth.log file which essentially
4:11:52gets rid of the authentication logs very
4:11:54very simple you can take a look at all
4:11:56the other logs and of course you might
4:11:58want to get rid of all the other logs
4:12:00that
4:12:00that might have existed before or in the
4:12:03fact in in regards to the services that
4:12:05you might have used so for example if
4:12:07you used mac changer which is quite rare
4:12:09you might want to get rid of that log
4:12:11file the kernel log file which is right
4:12:13over here so
4:12:14if we open it up
4:12:16kernel.log
4:12:18and there we are these are all the log
4:12:19files in regards to the to the kernel so
4:12:22again this is a file that you might want
4:12:23to get rid of or you can simply edit
4:12:25what you don't want in any of these log
4:12:27files so as to to to sort of throw off
4:12:31the forensic themes or off of your back
4:12:33to essentially make it look really
4:12:35really traditional all right so that is
4:12:37how to clear your log files of course
4:12:39you can use shred for deleting any other
4:12:42file this is a video not it's not
4:12:43designed to be uh to be about shred but
4:12:46there you go you can use shred to erase
4:12:48files uh permanently all right so do be
4:12:51careful with it as well now let's talk
4:12:53about bash history which is a video that
4:12:55most of you guys requested me to to talk
4:12:58about now bash history essentially keeps
4:13:00a record of all the commands that were
4:13:02executed by a user on the linux command
4:13:05line
4:13:06now this is very very important because
4:13:09the uh the bash history is a is a file
4:13:11that is kept uh
4:13:13usually separated for each individual
4:13:15user on the linux system so if you are
4:13:18the root user you have your own bash
4:13:19history file if there was a user called
4:13:22alexis he will also have his own bash
4:13:24history file you get the idea so
4:13:27the directory in which it is stored in
4:13:29is in the home user the user that being
4:13:32the user that you are using
4:13:34and the file is the dot bash history
4:13:37file
4:13:38all right so i'll get to that in a
4:13:39second so if there was a user
4:13:42let me just go back into the root
4:13:43directory and this is where it is stored
4:13:45so if you do have a user it is stored in
4:13:47the
4:13:48home and the username so this is where
4:13:50you put in the username and it is stored
4:13:52under the bash history file right over
4:13:54here
4:13:55all right
4:13:56so that is if you are using a particular
4:13:59use on the system which is quite obvious
4:14:01but if you do have root privileges then
4:14:03it's also important but you essentially
4:14:04want to get rid of all the bash history
4:14:06because this will essentially give
4:14:08forensics teams a list of all of what
4:14:11you did on that system
4:14:13all right so let me actually show you
4:14:15how this can be analyzed so i'm just
4:14:17going to open up nano here and since i'm
4:14:19in the root directory i think i should
4:14:20have the there we are the bash history
4:14:22file
4:14:24uh now i personally have a lot of
4:14:26important information in there so i'm
4:14:28going to simply show you how to get to
4:14:31wipe it all right now wiping it you can
4:14:33also use shred if you want to but i
4:14:35don't recommend doing that because again
4:14:37you're really starting to
4:14:39you're helping the forensic team build
4:14:42uh an idea of what type of attacker
4:14:44they're dealing with so i would
4:14:45recommend keeping things as normal as
4:14:47possible
4:14:48all right so if you you can also use the
4:14:50null redirect to clear the file which is
4:14:52what i'm going to do so you can
4:14:53essentially use the null redirect as
4:14:55follows so
4:14:56bash history
4:14:58and uh as on once i hit enter it will
4:15:00essentially clear the file because i'm
4:15:02using null redirect so it's essentially
4:15:04clearing the entire file so
4:15:06bash history let me open up the file
4:15:08sorry
4:15:09nano
4:15:10uh and um
4:15:13bash
4:15:14history as follows and there we are so
4:15:15it's empty now you might be wondering
4:15:17well it is empty but did it contain
4:15:19anything well if we start using the
4:15:21terminal here which uh am i currently
4:15:23using this so i'm using terminator
4:15:25uh yeah there we are so i was using a
4:15:27material session i was just working on a
4:15:29few hack the box videos which will also
4:15:31be coming out so don't worry about that
4:15:33so if i was to do your sudo apt get
4:15:36update
4:15:38there is a command that i did run and we
4:15:40try and open up the bash history file
4:15:42right over here and we'll let we let
4:15:44that running and that is in my uh
4:15:47terminator session all right so let's
4:15:48open it up one more time and uh for some
4:15:51reason it isn't showing up well we have
4:15:52to wait for the command to execute so
4:15:54uh let me just wait for that to execute
4:15:56so i'll get back to you when this is
4:15:58done
4:16:00alrighty i'm back i've essentially just
4:16:02ran a few commands i was just doing a
4:16:04bit of metasploit work i was using
4:16:07messer venom all that good stuff because
4:16:09i really wanted to show you how much
4:16:10information the bash history file can
4:16:13uh can actually reveal so let me just
4:16:15open it up one more time here
4:16:17and my terminal always lags out when i
4:16:20resume a video which is really weird
4:16:21something to do with my processor let me
4:16:23know if you guys know what's going on
4:16:25here alright so bash
4:16:28bash history like so when we hit enter
4:16:30and there you are so you can see that i
4:16:32was doing uh some very interesting
4:16:34things here
4:16:35so i went to my desktop i created a
4:16:38payload the message venom i copied the
4:16:42uh the payload to my apache directory i
4:16:45restarted apache
4:16:47uh looks like i removed a motility
4:16:50installation i also removed an
4:16:52index.html file
4:16:54uh well i cleared the terminal i'm
4:16:58actually missed i misspelled so yeah
4:17:00this reveals a lot of information about
4:17:02what the attacker was doing or what a
4:17:04particular user was doing on the system
4:17:06so
4:17:07so there you go and it'll also tell you
4:17:09that your attacker has really bad typing
4:17:12skills and really makes a lot of
4:17:13spelling mistakes so yeah you can pretty
4:17:15much get an idea of what exactly is
4:17:18going on here
4:17:19all right so that's pretty much going to
4:17:21be it for this video guys thank you so
4:17:23much for watching
4:17:24if you have any questions or suggestions
4:17:26let me know in the comment section on my
4:17:28social networks on my website and i'll
4:17:30be seeing you in the next video peace
4:17:32guys
4:17:36[Music]
4:17:47hey guys in this video we're going to be
4:17:49taking a look at ssh brute force
4:17:51protection with fail to ban now before
4:17:53we actually get started with setting it
4:17:55up let's get a bit of an understanding
4:17:57as to what this tool is and how we can
4:17:58use it
4:18:00for ssh brute force protection all right
4:18:02so what is fail to ban filter ban is an
4:18:04intrusion prevention framework that's
4:18:06written in python
4:18:08and that protects linux systems and
4:18:09servers from brute force attacks now
4:18:11these are not limited to ssh but the
4:18:13scope of this video is going to be based
4:18:15around ssh as the primary service that
4:18:18is going to be protected uh you know
4:18:19from brute force attacks
4:18:21all right so it allows you to monitor
4:18:23the strength and the frequency of
4:18:24attacks and then from that you can sort
4:18:26of create various jails that you can use
4:18:29and you can sort of customize your the
4:18:32strength of the defense you want to set
4:18:34up based on the attacks you're getting
4:18:36and of course fail to ban can be set up
4:18:38to block ip addresses automatically
4:18:40based on specific parameters more of
4:18:42which i'll explain as we move along all
4:18:44right so the great thing about fail the
4:18:46ban is that it automates the process of
4:18:48protecting your server
4:18:50or your ssh from brute force attacks
4:18:52alright so
4:18:53let's get started all right now that we
4:18:56have an understanding of what fail to
4:18:57ban is and how we can use it to protect
4:19:00our servers you know from brute force
4:19:02attacks on ssh
4:19:04let's take a look at the infrastructure
4:19:05we'll be using in this video
4:19:07so for the purpose of this video i've
4:19:08just set up a quick
4:19:10a quick server here with linux and i'll
4:19:12just copy the ip address it's just a
4:19:14simple ubuntu server and they'll
4:19:16demonstrate how powerful filthban
4:19:18actually is so i'll just open up a
4:19:20terminal here and we can try and log
4:19:22into this server right now i haven't set
4:19:24any any other user account so we'll be
4:19:26logging as the root user
4:19:27and let me just enter the password here
4:19:30and that should log us in immediately so
4:19:32the first thing i want to do is i want
4:19:34to update
4:19:35the packages because we do need to
4:19:36install fail to ban all right so i'm
4:19:38just going to say upgrade update here
4:19:40and we do need to run sudo there because
4:19:43we're already using the root user but in
4:19:45any case
4:19:46let's just update the packages here or
4:19:48the repositories sorry not our packages
4:19:52now filter ban is completely free to use
4:19:55and you know you can install it through
4:19:56most of your popular package managers in
4:19:58our case we're just going to use the
4:19:59aptitude package manager so as a apt-get
4:20:03install and we're going to say fail to
4:20:05pan and we hit enter
4:20:07and that is going to prompt us to
4:20:09download about 18.7 megabytes and we're
4:20:12just gonna let that install
4:20:13uh this shouldn't take uh too much time
4:20:16and we can see we do have a sim link
4:20:18created here that's very important for
4:20:19the filter band service so one of the
4:20:22first things we need to do is we need to
4:20:23ensure that we have enabled fail to ban
4:20:25to run on on system startup so in the
4:20:27event you do reboot your server uh you
4:20:30need to make sure that filter ban you
4:20:31know runs
4:20:32directly on the startup or during the
4:20:34startup so to do this we'll use a
4:20:36systemd so system control and we'll say
4:20:39um enable
4:20:41uh of course we're gonna say fill to ban
4:20:44and the service is actually called fail
4:20:46to ban dot service so we're gonna hit
4:20:48enter
4:20:48and as you can see it's gonna say
4:20:50synchronizing the state of the
4:20:51filterband service with the csv
4:20:54service script uh so irregardless of
4:20:56whether we used systemd
4:20:59so
4:21:00what we can do now is we can start
4:21:02taking a look at the configuration files
4:21:04right now the configuration files
4:21:07for failed ban are going to be found in
4:21:09the etsy uh they're in the etsy
4:21:11directory so we can say um let's just
4:21:13list all the files etsy
4:21:15fail to ban and we hit enter and let's
4:21:17take a look at these configuration files
4:21:19so the most important one that you want
4:21:21you want to be familiar with is are
4:21:23going to be the jail dot conf file and
4:21:25the filterband.com file or the
4:21:27filterband.com file is a file we'll not
4:21:29be taking a look at
4:21:30uh in this video but we're taking a look
4:21:32at the actual jail.configuration file
4:21:34now uh uh if a fairly frequent or common
4:21:38term that you'll be hearing uh you know
4:21:40that will hear being mentioned when
4:21:41talking about fail the ban is the use of
4:21:43jails all right so what is a jail in
4:21:46filter ban well a jail is essentially a
4:21:48configuration file
4:21:50that you know contains filters or
4:21:52arguments that protect your system or a
4:21:54particular service now by default all
4:21:57your jails for particular services are
4:22:00going to be in the jail.conf file
4:22:02alright so if i just get the contents or
4:22:04let's actually view the entire file we
4:22:06can say um
4:22:08let me move into the directory so it's
4:22:10much easier for us to work there
4:22:12so we can say less and we say
4:22:15jail
4:22:17jl.conf and we hit enter uh you can
4:22:20pretty much see that first of all it
4:22:21tells you that uh this is not the uh the
4:22:24appropriate way of actually creating or
4:22:27modifying the already preset jails the
4:22:29reason being is this we should actually
4:22:31create another jail.configuration file
4:22:34uh with the local extension so you can
4:22:36see in most of the cases you should not
4:22:38modify this file but provide
4:22:39customizations in the jail.loc of the
4:22:42gel.local file or you can create
4:22:45separate.con files under the jl.d
4:22:47directory something we're not going to
4:22:48be doing because the gel.local file is
4:22:50pretty much the best way of going about
4:22:52it so what you can do is you can copy
4:22:54this file and you know you can make a
4:22:55copy of it however the second copy is
4:22:57going to be called jail.local
4:22:59in within this uh it has various jails
4:23:02that protect various services now the
4:23:04first one you can see
4:23:06is uh going to be the sshd or the
4:23:08openssh server service and it's going to
4:23:10be enabled so a jail has already become
4:23:13uh has already been configured for this
4:23:15but you can see that there aren't any
4:23:17protection uh configuration options that
4:23:19have been set here
4:23:21so for example the band time the default
4:23:24band time for all jails on all services
4:23:26irregardless of whether it's ssh or ftp
4:23:28has been set to one hour now we can
4:23:31pretty much customize this for uh
4:23:32particular services which is what we
4:23:34want to do so you can use this uh this
4:23:37same configuration file uh and you can
4:23:39copy it you know and use the local
4:23:41extension and this will essentially set
4:23:43up protection for all of those services
4:23:45however in our case i want to
4:23:47i want to actually create a new
4:23:49jail.local file and the only service
4:23:51that i'm going to be protecting or we're
4:23:52going to be configuring is the
4:23:54the the openssh server this sshd service
4:23:57so again all we'll do is we will say um
4:24:00we'll use them here and we'll say
4:24:02jl.local
4:24:04and we're going to hit enter now as you
4:24:06already saw within the gel.configuration
4:24:09file
4:24:10we can essentially
4:24:12we we can start working with these
4:24:14services that we want to protect so
4:24:16again we do this by specifying their
4:24:18name so in our case the openssh server
4:24:20is defined by the ssh daemon here so
4:24:23we're going to say ssh daemon and then
4:24:25after this we're going to start
4:24:27providing the syntax now the first
4:24:29important bit of syntax here is going to
4:24:31be the enabled configuration or the
4:24:33enabled option
4:24:35this essentially you know
4:24:37means whether this essentially controls
4:24:39whether the jail is enabled uh or
4:24:41disabled and the option here we can
4:24:43specify is either true or false right
4:24:46and of course that is self-explanatory
4:24:49enabled means that the uh the jail or
4:24:52the protection will be enabled or this
4:24:54these particular configurations will be
4:24:56enabled so for now let's just keep it at
4:24:58false because i want to show you uh you
4:25:01know a test brute force attack on the
4:25:02server
4:25:03uh before and after so what we'll do is
4:25:06we'll just say false
4:25:08and uh
4:25:09after this we can then get started with
4:25:11our configurations now let me just talk
4:25:12about the various configurations that
4:25:14exist here
4:25:16uh so we pretty much need to specify the
4:25:18service the port and the filter and the
4:25:21log file that we'll be using now let me
4:25:23explain that sounds like a mouthful but
4:25:24it's really very simple to understand
4:25:27all right so the first thing i want to
4:25:28do is i want to say what's the pot the
4:25:30port is going to be the ssh port right
4:25:33so the ssh port here
4:25:35and
4:25:36after this we specify the filter that
4:25:38we're looking for now the filter is
4:25:40something very important right so let me
4:25:42just open up a uh
4:25:43i'll open up a new tab here and we can
4:25:46try and authenticate to this server one
4:25:48more time so i'll just say ssh root and
4:25:51we'll just authenticate to this server
4:25:53and the reason being is i want to show
4:25:55you the log the log file that we're
4:25:57talking about this is the auth.log file
4:25:59now the auth.log file uh pretty much
4:26:02stores all the authentication attempts
4:26:04made to the server whether they they
4:26:05were successful or whether they failed
4:26:08and pretty much you can find this within
4:26:11the let's just get the contents of the
4:26:13file so you can find this within the log
4:26:15directory under etsy and it's called the
4:26:17author log file now when i talk about a
4:26:19filter again a filter is very simple to
4:26:22understand uh we'll just hit enter for
4:26:24some reason we don't have
4:26:27this file we're looking sorry this is in
4:26:29the var directory my apologies i'm just
4:26:32getting confused with the etsy directory
4:26:33there so you can see that this gives you
4:26:35um
4:26:36it gives you a log here of all the
4:26:38authentication attempts
4:26:40and when i was talking about the actual
4:26:42filter so if i say filter
4:26:44this will essentially mean this is
4:26:47essentially where you say fail to ban i
4:26:49want you to look for this particular
4:26:52filter in our case we're looking for the
4:26:53ssh daemon or the sshd service here so
4:26:56you can see
4:26:57that for example if we take a look at
4:26:59the first ssh
4:27:01demon
4:27:02log here we can see that this is the the
4:27:04ssh server listening on port 22 and then
4:27:07if we take a look at some authentication
4:27:09attempts you can see we have an
4:27:10authentication attempt here
4:27:12that tells us accepted password for the
4:27:14root user and the particular ip address
4:27:17here
4:27:18and this was made through ssh not a tty
4:27:21session so if it can also tell you
4:27:23whether the authentication is done
4:27:25locally or remotely so that is the
4:27:27filter we're looking for so we only want
4:27:29to filter for ssh daemon or sshd
4:27:32logs there so we then need to specify
4:27:35the the location of the log file that
4:27:37we're going to be using so say log path
4:27:39is going to be equal to and we specify
4:27:41the relative directory here so we're
4:27:42going to say var
4:27:44log
4:27:45and auth.log here
4:27:48and after this we can just hit enter and
4:27:50we can now talk about the security
4:27:52options right so the security options
4:27:54are very simple the first or the first
4:27:56of with of which is the most important
4:27:59this is the max retry option and this is
4:28:01where you specify the number of attempts
4:28:03to be made before an ip address or a
4:28:06user is banned all right so to do this
4:28:08we say max retry
4:28:10max retry and that's going to be equal
4:28:12to in our case we'll just say three so
4:28:14the number of uh so we say the number of
4:28:16attempts to be made before a band is
4:28:18going to be equal to three so if you
4:28:20enter
4:28:21you know an incorrect password three
4:28:22times that's that you're going to be
4:28:24banned right
4:28:25now we then have the band time right so
4:28:27the band time
4:28:29is again self explanatory this is the
4:28:31number of seconds an ip address will be
4:28:33banned for now typically you can set it
4:28:35to an hour which is uh is primarily
4:28:38going to be uh you know 3600 seconds or
4:28:41you can uh you can specify a day which
4:28:44is a very good option that many system
4:28:47administrators set so again
4:28:49we can just calculate this so 60 times
4:28:5260 um that pretty much gives us what
4:28:54we're looking for that's 3600 multiplied
4:28:57by 24 hours that's going to be 86 400 so
4:29:01we can say 86
4:29:04400 and that's typically going to block
4:29:06uh any ip addresses that have incorrect
4:29:10authentications more than three or uh
4:29:12three incorrect authentications for
4:29:14entire day
4:29:15right so what we can do is we'll just
4:29:17set it to 3600 or we can set it to 60
4:29:20seconds whatever you feel is appropriate
4:29:22for your server based on the attacks
4:29:24you've been getting or you can set a
4:29:25generic one if you're monitoring your
4:29:27server and seeing how many attacks
4:29:29you're typically getting which i'll show
4:29:31you how to monitor
4:29:32you can then ignore ip addresses so you
4:29:35can whitelist ip addresses
4:29:37so again that's done by specifying
4:29:39ignore ip and then within this you can
4:29:42then specify any ip addresses that you
4:29:44may want to white if you're a system
4:29:45administrator it may be wise to enter
4:29:47your ip address here
4:29:49um so you can do that and i think
4:29:52we can also specify uh i've specified
4:29:55band time what about find time so the
4:29:57amount of time between failed uh login
4:30:00attempts
4:30:01we can you can just say find time
4:30:05or we can actually leave that out
4:30:06because we really don't need that uh
4:30:08these are these options are pretty
4:30:10pretty good um so we can save
4:30:13this file
4:30:15and we
4:30:16we
4:30:17ensured that this jail was disabled and
4:30:19the reason being is i want to show you
4:30:22what you know typical field
4:30:23authentication looks like
4:30:25so what i'll do is um let me just exit
4:30:28from here and i'll just
4:30:31ssh into this and i'll enter incorrect
4:30:33passwords now typically the the
4:30:36the max amount of times you're allowed
4:30:37to authenticate incorrectly is three
4:30:39times that's the default one but i'll
4:30:41explain something interesting here so
4:30:43for example
4:30:44uh actually before i do this because i
4:30:46do want to block my ip address because
4:30:48it is going to connect to it remotely
4:30:51let's see if we can actually use proxy
4:30:53chains here so let me just open up this
4:30:55in part os and i'll expand this
4:30:59uh or we can actually use anon surf so
4:31:01let me just use anon surf instead of
4:31:02using proxy chain so we'll just start
4:31:04this
4:31:05yes go ahead
4:31:07and the reason being is i don't want to
4:31:09actually expose my real ip address here
4:31:11because when i'll be showing you the ip
4:31:13addresses that were blocked uh this will
4:31:15come into play so what i'll do is i'll
4:31:17just wait for announcers and on surf to
4:31:19start before we authenticate to the
4:31:21server and i'll show you what happens
4:31:24here
4:31:24so remember the jail has is currently
4:31:26disabled and ssh protection is is
4:31:29currently not active with fail to ban
4:31:31all right so we are currently uh
4:31:34anonymized here so what we'll do is
4:31:35we'll say ssh
4:31:37root at
4:31:38and we'll hit enter
4:31:40and we'll say yes we want to accept the
4:31:42fingerprint and we'll enter incorrect
4:31:44password so i can just say password
4:31:47and again that will be incorrect
4:31:49permission denied
4:31:50password will hit enter
4:31:53another incorrect password attempt for
4:31:56authentication attempt hit enter one
4:31:58more time
4:32:00and there we are you can see so it gives
4:32:02you three attempts by default and then
4:32:04after which you're told permission
4:32:05denied let's try this one more time so
4:32:08we're we're sort of exceeding the amount
4:32:10of attempts but remember we haven't
4:32:11enabled the fail to ban jail so we can
4:32:14still try authenticating incorrectly
4:32:16say password
4:32:19and
4:32:20password let's try it a few more times
4:32:22and there we are we can still see that
4:32:24after three unsuccessful attempts
4:32:27uh it uh it it essentially disconnects
4:32:29the the connection what i'll do is we'll
4:32:32just wait for we'll just close this and
4:32:34uh let's restart the service before we
4:32:36actually get started so again uh before
4:32:38after writing any changes to your uh to
4:32:41your jail configuration file
4:32:43uh you essentially need to restart the
4:32:45the filterband service so we say system
4:32:48control
4:32:49sorry system
4:32:50system control and we say restart
4:32:53uh we'll say fill a two band service and
4:32:57we
4:32:58hit enter and that's going to restart it
4:33:00so now that we've tested that this uh
4:33:02that we you know we currently do not
4:33:04have any brute force protection here uh
4:33:07what we can do is we can modify this
4:33:09file and we can say uh set this to true
4:33:12so now we're going to activate the
4:33:13protection so we're gonna say true
4:33:16and we're going to write changes and
4:33:18exit and we'll restart the filter band
4:33:20service and let me just check the status
4:33:22here
4:33:24[Music]
4:33:27sorry that is incorrect
4:33:29we'll just change this to status and we
4:33:31can see it's active and running this is
4:33:33very important because
4:33:36if you do want to actually check if
4:33:38you're having any issues with your
4:33:39syntax or any of the filters you've set
4:33:42up for your particular jail in the jail
4:33:44configuration file
4:33:46this is where you can actually check if
4:33:47there are any issues and you also have
4:33:49the log here so you can see stopped
4:33:50start started and we're ready again so
4:33:54we can now get started and we can test
4:33:56it one more time so what i'll do is i'll
4:33:58use the same ip address here
4:34:00and what we'll do is we'll just say ssh
4:34:03root act
4:34:04and for some reason we're being told the
4:34:06connection was closed by remote host
4:34:09so let's try a different ip here so uh
4:34:12let's see if we can let's check the
4:34:15um
4:34:16the status of of the tor service
4:34:19and we remember we need uh
4:34:22do we have tor running we currently have
4:34:24door running i believe but i think we
4:34:26still need to disable the anon surf here
4:34:29we can just stop it
4:34:32uh so we'll say stop and we'll wait for
4:34:34this to stop
4:34:36and i think we can just use proxy chains
4:34:38now that would be much better
4:34:40uh instead of using anon surf
4:34:43although i should have done that before
4:34:45but i just wanted to explain a point
4:34:46here so
4:34:48all anonymous mode has been stopped and
4:34:52we'll just start store
4:34:55uh actually yeah we can we can do we'll
4:34:57start it and uh now let's use proxy
4:34:59chains i'll say proxy chains
4:35:02ssh um i'll say root at and we'll paste
4:35:06the ip in here
4:35:08all right so it'll ask us for the
4:35:10password and i'll just enter an
4:35:11incorrect password late enter
4:35:14and uh lend an incorrect password again
4:35:17remember we have said we have set the
4:35:18options in the gel configuration file to
4:35:20three so again it will just uh it will
4:35:22block the user for the first three
4:35:23attempts obviously
4:35:25uh we aren't getting a response we can
4:35:27also try brute forcing with hydra
4:35:30which is also another option so let's
4:35:32try this out so we'll say
4:35:34hydra
4:35:35uh l uh we'll say root
4:35:39and the password list is gonna be user
4:35:42uh share
4:35:44and we're gonna say word lists and we'll
4:35:46use some of the meta split word lists
4:35:48here
4:35:48uh let's see which ones we have
4:35:51do we have any ssh ones
4:35:53nothing much
4:35:57we can use the common roots let's try
4:35:59that we can just use any the the bottom
4:36:01line is i just want to show you
4:36:03what this would look like
4:36:05so we're looking for ssh
4:36:07and we specify the ip address here
4:36:09let's get rid of any other sessions that
4:36:11i had and let's have some verbose output
4:36:14and let enter
4:36:15and you can see it tells us that could
4:36:16not connect to
4:36:18to this particular ip
4:36:20connection refused what i'll do is uh we
4:36:23can you can see that after the third
4:36:25failed attempt
4:36:27we can see that we get no response and
4:36:28that actually proves that it's working
4:36:30however i'll i'll actually show you how
4:36:32you can check this so if we just
4:36:34terminate this and we go back in on to
4:36:37our server we can view the logs and the
4:36:39failed authentication attempts and the
4:36:41blocked ips
4:36:42uh by taking a look at the filter ban
4:36:44client here so i can hit enter and then
4:36:47after this we want to display the status
4:36:49right so if i hit status and we hit
4:36:51enter this will give you the number of
4:36:53jails that you have and as you can see
4:36:54we have only one gel and that is the ssh
4:36:57daemon so we want to check the status of
4:36:59the ssh
4:37:01daemon or this is ssh server as the
4:37:03openssh server
4:37:05uh jail and we hit enter all right and
4:37:08you can see that the status for the jail
4:37:10is as follows so the filter is
4:37:12the currently failed is zero the total
4:37:15amount of failed authentication attempts
4:37:17is six
4:37:18uh you then have the file list which is
4:37:20uh the authentication log that is going
4:37:22through uh it's banned three ip
4:37:24addresses so the total amount of band
4:37:26ips is three you have the band ips that
4:37:29i think we used with unknown surf
4:37:31and also with store and my ip address
4:37:33here which for some reason it blocked i
4:37:35think that's because i disabled
4:37:37um i think i disabled announcers and
4:37:40pareto's using my ip in any case
4:37:43so what we can do now is we can go back
4:37:45into parrot and um
4:37:48if we take a look at hydra we can see
4:37:50that we have a few issues here so let's
4:37:52test this one more time by running anal
4:37:54surf
4:37:55again and then we'll try and run hydra
4:37:57with that so that we have a new ip we
4:37:58can work with
4:38:00because it looked through the filter
4:38:01bank line that it did work um
4:38:04so and when i'd run
4:38:07i'd run proxy chains with hydra here
4:38:10uh because actually didn't run proxy
4:38:12chains directly so if i try and do that
4:38:14right now we can actually do it here so
4:38:16we can save proxy chains
4:38:18um
4:38:20we'll wait for this to connect first so
4:38:21we're currently on the announcer tunnel
4:38:24so we can just run it through this so we
4:38:26hit enter
4:38:27there's going to test if possible
4:38:28authentication is supported and you can
4:38:30see it is working and
4:38:33immediately we're getting a few
4:38:34connection errors so
4:38:36it's going to try connecting again but
4:38:39what we can do is um
4:38:41[Music]
4:38:42we can say sudo
4:38:44we'll say
4:38:46proxy chains and we'll run this with
4:38:49hydra right and i'll enter my password
4:38:51here
4:38:52so we can see that it's currently
4:38:54supported
4:38:56and
4:38:57immediately we get uh authentication
4:38:59errors to the server so that's working
4:39:01fine let's take a look at the filter
4:39:03bank client one more time so again i'll
4:39:06just clear that out and we can run the
4:39:09fill to burn client and check the number
4:39:11of failed authentication attempts again
4:39:14and now you can see that again the
4:39:16amount of failed authentication attempts
4:39:18has moved up to 38
4:39:20and the currently the the total amount
4:39:22of band ip addresses are as follows so
4:39:25we have various ones that we had uh that
4:39:27we have uh that we got with anon surf
4:39:30and proxy chains to uh
4:39:32to a certain extent so
4:39:34uh that's pretty much how to view
4:39:37um
4:39:38this is pretty much how to view all the
4:39:39failed authentication attempts and the
4:39:42blocked ips which you can then use to
4:39:43build a geographical model of where most
4:39:46of the attacks are coming from even
4:39:47though they may be coming from a botnet
4:39:49uh so again that's how to use feldeban
4:39:51uh so again if you want to disable a
4:39:53particular jail uh we can just check
4:39:55this out here
4:39:57uh fill the ban and you can then modify
4:39:59the local configuration file so we can
4:40:02use fim and we say jail dot local
4:40:05and we enter so if i'm working with the
4:40:07ssh daemon i can just disable this
4:40:10to false here and that will disable the
4:40:12protection
4:40:13and if i just run and exit and we can
4:40:16try and restart this service so i can
4:40:18say
4:40:20system control
4:40:23we can say restart
4:40:25oops sorry
4:40:26restart let me just reduce the font size
4:40:28here and we'll say fill to ban
4:40:31service and we'll hit enter
4:40:34and there we are
4:40:35all right uh let's take a look at
4:40:38whether we can actually log in now
4:40:41so i'll say exit
4:40:42and this is through my local ip i'm not
4:40:44going to use proxy chains
4:40:46um so i'll say
4:40:48ssh will actually just ssh without proxy
4:40:50change ssh
4:40:52root at this particular ip and you can
4:40:55see it now works perfectly fine so if i
4:40:57hit another
4:40:58uh you know some other incorrect
4:41:00passwords we are now able to
4:41:03at least get authentication attempts
4:41:05across the line uh but yeah that's
4:41:08pretty much all that i wanted to show
4:41:09you guys how to do um you know with
4:41:11failed by how to use fill the band you
4:41:13know to protect to protect your server
4:41:15from uh ssh brute forces uh let me know
4:41:17if you have any questions or suggestions
4:41:19and i'll be seeing you in the next video

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