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Common Ports - CompTIA Network+ N10-009 - 1.4 — Transcript

by Professor Messer · 3,161 words · 484 segments · language en · Watch on YouTube

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0:02as a networking professional you may be
0:04asked to configure port numbers
0:05associated with a particular application
0:08so in this video we'll look at the
0:10well-known port numbers associated with
0:12those apps we'll start with a generic
0:15form of file transfer that's used across
0:17many different operating systems this is
0:20FTP or the file transfer protocol this
0:23is a very common and generic form of
0:25file transfer that can be used on Linux
0:28Windows Mac OS and practic Ally any
0:30other operating system unlike many
0:33applications that use a single port
0:35number to communicate FTP is configured
0:37to use one or two different port numbers
0:40specifically TCP Port 20 and TCP Port 21
0:44TCP Port 20 is commonly associated with
0:47the file transfer process itself and
0:49Port 21 is commonly sent to send control
0:52information between one device and
0:54another FTP has an authentication method
0:57so you can use usernames and passwords
0:59and when transferring information you
1:01can choose to not only transfer the file
1:03you can List information in a particular
1:05directory add different files delete
1:08rename and perform other types of file
1:11maintenance TCP Port 22 is commonly
1:14associated with SSH or secure shell this
1:18is a way to communicate to a Remote
1:20device from a console so you have this
1:22textbase front end and you're able to
1:24configure and manage this device over
1:26this text based command line interface
1:29and important characteristic of SSH is
1:32the secure part of SSH because all of
1:35the communication between your device
1:37and that Remote device is all sent
1:39across the network in encrypted form
1:43well if there's encryption being used
1:45with secure shell it would be great if
1:47we could use encryption with our file
1:49transfer protocol so of course there is
1:51a version of the FTP called secure FTP
1:55or
1:56SFTP this allows us to transfer files
1:59from one device to another and that
2:01entire communication across the network
2:03is all encrypted by default
2:05interestingly enough secure FTP is
2:08really using the SSH protocol to be able
2:11to perform this encryption so SSH and
2:14SFTP use the same port number of TCP
2:17Port 22 and just like our FTP protocol
2:21that allows us to perform file
2:22management of that device we can also
2:25perform the same file management using
2:27the secure version of FTP so you can
2:30view the directories you can make
2:31changes to the directory names you can
2:33modify files delete information and
2:36perform all of the normal file
2:38management from the secure FTP
2:40application both secure shell and secure
2:43FTP have that Foundation of SSH as the
2:46underlying protocol so not only does
2:48secure shell allow you that remote
2:51terminal communication you can also have
2:53remote file transfer communication and
2:56all of that communication will be
2:58encrypted using the s SSH protocol over
3:01TCP Port
3:0322 before we had encryption over SSH or
3:07secure shell we used a non-encrypted
3:09form of terminal communication referred
3:12to as telnet this stands for
3:14telecommunication Network and it
3:16commonly uses TCP Port 23 visually this
3:20looks almost identical to what we use
3:22with secure shell the difference however
3:25is the communication that we're sending
3:27between our device and the remote
3:29station is all being sent in the clear
3:31there's no encryption that's taking
3:33place across the network this means that
3:35someone could potentially capture those
3:38packets and view everything that's being
3:40sent back and forth over the network
3:42including your login credentials it's
3:44for this reason that you don't commonly
3:46see telnet being used on our Network and
3:49instead we'll use SSH to ensure that all
3:51of this communication will always be
3:54encrypted another important application
3:56on our network is the use of email and
3:59of course we need protocols to be able
4:01to transfer these emails from one email
4:03server to another to be able to do that
4:05we use SMTP or the simple mail transfer
4:09protocol SMTP is commonly associated
4:12with server to Server email transfers
4:14using TCP Port 25 all of this traffic
4:17sent over TCP Port 25 is sent in the
4:21clear or in plain text there's no
4:23encryption that's automatically
4:25configured when using TCP Port 25 that's
4:28why many SM TP servers will use TCP Port
4:32587 which is SMTP using TLS encryption
4:36or the transport layer security SMTP is
4:40also used from client devices that are
4:43sending email messages and it's often
4:46sending those to a mail server using
4:48this SMTP protocol for receiving email
4:52messages and being able to manage your
4:54email inbox we often use other protocols
4:56such as IMAP or pop 3 so any time that
5:00you are sending email or you're
5:02transferring email between email servers
5:04you're probably using SMTP or the simple
5:07mail transfer
5:09protocol we don't often memorize the IP
5:12address of devices that we communicate
5:14with instead we use the fully qualified
5:17domain name or fqdn and the way that we
5:20translate between the fully qualified
5:23domain name and the IP address is we use
5:26a DNS server and that stands for domain
5:28name system DNS commonly uses UDP Port
5:3253 to be able to perform this name query
5:35so we'll ask a DNS server what the IP
5:38address of www.professormesser.com might
5:41be and it will respond back with the IP
5:44address that your device can use to
5:46communicate to that server for those
5:48small queries we commonly use UDP Port
5:5153 but if there's a large transfer of
5:53data from one DNS server to another we
5:56commonly would use TCP Port 53 these DNS
6:00servers are obviously very critical
6:02resources because without them we
6:04wouldn't be able to communicate to
6:05servers such as professormesser.com this
6:08is also a very common protocol to find
6:10on the network and if you take a packet
6:12capture you're almost guaranteed to
6:14capture some type of DNS
6:16traffic we become very accustomed to
6:19Simply plugging into a network or
6:21connecting to a wireless network and
6:24automatically being able to communicate
6:26across that network but behind the
6:28scenes there is an automat IP
6:30configuration process using DHCP or the
6:33dynamic host configuration protocol this
6:36is the protocol that allows us to
6:38automatically configure IP address
6:40settings for anyone that connects to the
6:42network by default DHCP uses UDP Port 67
6:46and UDP Port 68 to be able to use DHCP
6:50we need a DHCP server at home we
6:53commonly use a DHCP server that's
6:56integrated into an existing wireless
6:58router but in an Enterprise Network
7:00there are often Standalone DHCP servers
7:03we usually configure a pool of IP
7:06addresses on DHCP and anyone who
7:08connects to the network will be
7:10automatically assigned an IP address
7:12from this available pool of addresses
7:14there's also a lease time associated
7:17with this IP address so you're only able
7:19to use that IP address for a certain
7:21amount of time and if you are still
7:23using that address at the end of the
7:25leasing period you can choose to renew
7:27that lease with the DHCP server
7:30we can also configure certain devices to
7:32always receive the same IP address every
7:35time they connect to the network and we
7:37associate that IP address with the MAC
7:39address of that device we configure that
7:42in the DHCP server that's often referred
7:44to as a DHCP reservation all of this
7:47communication that occurs across the
7:49network for DHCP will almost always use
7:52UDP Port 67 and UDP Port
7:5568 we talked earlier about the FTP or
7:59file transfer protocol that we use to
8:01send files from one device to another
8:03and we describe the process of
8:06authentication and the many different
8:08management functions associated with FTP
8:11but what if you just needed to transfer
8:13a small bit of configuration information
8:15from one device to another you don't
8:17need to view the name of a directory or
8:20change any of the file names you simply
8:22need to transfer a small amount of
8:24information very very quickly to be able
8:27to do that you might use tftp or the
8:30trivial file transfer protocol and by
8:32default it uses UDP Port 69 you'll often
8:36see tftp used for very simple file
8:38transfers usually this is something that
8:40doesn't require any type of
8:42authentication or login process so it
8:44may be something like a Voiceover IP
8:47device that has no IP address and no
8:49configuration and when you plug it into
8:51the network it is powered on using power
8:53over ethernet it uses DHCP to get an IP
8:57address and then it uses TFT TP to be
9:00able to download the latest
9:01configuration file from the server this
9:04is a quick and easy process it transfers
9:06data without any extra overhead it's
9:09able to do that very efficiently and
9:11very quickly using UDP Port
9:1469 if you're communicating to a web
9:17server you're probably using one of two
9:19different port numbers this is using
9:21HTTP or
9:23https this stands for hypertext transfer
9:26protocol and it's a communication that
9:28is commonly associated with
9:30browser-based communication if the
9:32information between your browser and the
9:34web server is being sent in the clear
9:36without any type of encryption it's
9:38commonly using TCP Port 80 if you need
9:41to perform encryption of that data and
9:44that is probably the default for most
9:46websites that you'll visit these days it
9:48is using SSL that stands for secure
9:51sockets layer or newer version of SSL
9:54referred to as TLS or transport layer
9:56security if this is encrypted data then
9:59it's probably using TCP Port 443 which
10:02is sending
10:04https for
10:05secure another thing you may notice with
10:08the devices that are connected to the
10:09network is they all tend to have the
10:12correct time and date down to the second
10:15level we're able to do that through an
10:17automated process called ntp or the
10:20network time protocol every device on
10:23the network operating systems routers
10:25switches and any other device can use
10:28ntp to stay synchronized with their
10:30clock across all of those different
10:32devices by default ntp uses UDP Port 123
10:37being able to synchronize these clocks
10:39is more than simply a convenience in
10:42fact it can be a very critical part of
10:44synchronizing log files between very
10:46diverse devices this allows us to go
10:49back in time and piece together
10:51Communications even though that
10:53communication occurred on many different
10:55devices this is a process that usually
10:57occurs automatically behind the scenes
11:00and many devices will synchronize their
11:02clock multiple times during the day
11:04using the ntp protocol you might also be
11:07able to configure this process maybe
11:09you'd like a device to update its clock
11:11every hour or maybe simply updating once
11:13a day is sufficient this is also a very
11:16accurate way to keep these clocks in
11:19synchronization and usually we get about
11:21a 1 millisecond difference between
11:24devices that are all on the same network
11:26this provides a level of granularity
11:28that's sufficient for most applications
11:31and it's something that occurs
11:32automatically using UDP Port 123 and the
11:35network time
11:37protocol as a network professional
11:39you'll be responsible for the uptime and
11:41availability of routers switches
11:44firewalls and many other devices on the
11:46network one way to manage those devices
11:49is through a protocol named SNMP or the
11:52simple Network management protocol by
11:55default SNMP uses UDP Port 161 to query
12:00devices and receive information about
12:02how that device may be performing for
12:05example we might have a management
12:06station and we might be querying a
12:08device to determine how much traffic has
12:11traversed that particular device over a
12:13certain amount of time and then it can
12:15provide us with a summary of how much
12:17data has been transferred over that time
12:20frame we can then store that data create
12:23graphs reports and other information
12:25that allows us to manage that device you
12:28might also find that different versions
12:30of SNMP may be used on your network
12:33version one of SNMP is the original
12:35version this allows your management
12:37station to perform a single query to
12:39this device and receive a single
12:41response and all of this is sent over
12:43the network in the clear with no
12:45encryption version two of SNMP allowed
12:48for bulk transfers so we can ask for
12:51many different variables from this
12:52device and receive a large group of data
12:55from that device which simplified the
12:57network communication and made it much
13:00more efficient but it didn't provide any
13:02type of encryption all of this
13:04information is still being sent across
13:05the network in the clear a more modern
13:08version of SNMP is what you may commonly
13:10find on your network today which is
13:12version three this is a more secure
13:15standard for SNMP which allows message
13:18Integrity authentication and encryption
13:20of the SNMP data one of the things
13:23you'll find with this default use of
13:25SNMP is the management station is
13:28interacting actively making a query and
13:31then receiving a response for that query
13:33so it's up to the management station to
13:36initiate that communication but it would
13:38be nice if these devices could identify
13:41problems and proactively send that
13:43information down to the management
13:45station we can do that by using a
13:47feature of SNMP called an SNMP trap this
13:51allows these notifications to be sent
13:53directly from these devices using UDP
13:56Port
13:58162 many organizations may have hundreds
14:01or thousands of devices on their Network
14:03and it may be a challenge to be able to
14:05keep track of what devices are on the
14:07network what users are connecting to
14:09those devices and how the relationship
14:11might be between the user and the device
14:14we're able to maintain a database of all
14:17of these devices and all of these users
14:19through a protocol named ldap ldap
14:22stands for lightweight directory access
14:24protocol and it commonly uses TCP port
14:27389
14:29ldap allows us to very easily query
14:31these databases and retrieve information
14:34that we may have stored there's also a
14:36secure version of ldap called ldap
14:38secure it uses TCP Port
14:42636 ldap uses a hierarchical structure
14:45to be able to layout the network and the
14:48devices this is a graphical view of an
14:51ldap database it starts with the root of
14:53the database which is an organization in
14:56this case the organization is Messer
14:58Studios we've also grouped together like
15:01devices into organizational units there
15:03is a production OU a support OU and an
15:07engineering OU within those
15:09organizational units there may be common
15:12name devices for example there may be
15:14users such as Jack and Daniel or there
15:17may be a database or storage device
15:19named Tech docs we're able to organize
15:22and access these devices through this
15:24structure making it a very common and
15:27simplified way of gaining access access
15:29to this
15:30data Microsoft Windows has some very
15:33unique features when it comes to data
15:35transfer Microsoft stores information on
15:38the network in a file share you can also
15:40share printers through Microsoft's
15:42operating systems and there's also
15:44authentication built into this entire
15:47process to be able to provide all of
15:49this functionality there is a
15:51specialized protocol named SMB or server
15:54message block to be able to share files
15:57share printers or authenticate to the
15:59network you might also see this referred
16:01to as cifs or the common internet file
16:05system SMB is integrated into Windows
16:08itself you don't need to add additional
16:10software there's no additional FTP or
16:13SFTP process instead built into the
16:16Windows Explorer or the file explorer
16:18within Microsoft Windows is the SMB
16:21functionality that allows us to access
16:23file shares print to remote printers
16:26lock different files on the network and
16:28provide processes for authentication and
16:31permissions for all of that data early
16:34versions of Microsoft Windows used the
16:36net bios protocol to be able to
16:39facilitate this communication but most
16:41modern versions of Microsoft Windows
16:43communicate directly across the network
16:45using IP and TCP Port 445 is the one
16:49that is usually associated with server
16:52message block or
16:54SMB as a network professional you'll
16:57find that you are constantly referring
16:59to logs that are being kept on your
17:01routers your switches your firewalls
17:03your servers and almost any other device
17:06that's connected to the network One
17:08Challenge is being able to consolidate
17:10all of these different log files to one
17:12single location and there is a
17:14standardized protocol for transferring
17:16these log files called CIS log CIS log
17:19commonly uses UDP Port 514 to be able to
17:23transfer this log data across the
17:25network you'll often use CIS log in
17:28conjunction with a security information
17:30and event manager or a Sim this is a
17:34consolidation point where you can have
17:36all of your log files transferred into
17:38one single Consolidated database so if
17:41you're using CIS log and transferring
17:43that over UDP Port 514 then you're
17:46probably transferring it to a very large
17:48Drive array or some other device where
17:51you can collect that log information
17:53over an extended period of
17:55time we store a lot of very diverse
17:58information on our databases but
18:00fortunately there is a very common form
18:03of storage and retrieval for those
18:06databases referred to as a structured
18:08query language or SQL some people refer
18:11to this as SQL this SQL database uses a
18:15standard language that you can use to be
18:17able to query and retrieve information
18:20from that database Microsoft has its own
18:23form of SQL database called the
18:25Microsoft SQL server or mssql
18:28stands for Microsoft structured query
18:31language and it very commonly uses TCP
18:33Port
18:341433 there are other types of SQL
18:37databases you might find on your network
18:39and they usually use different port
18:41numbers so if you see TCP Port 1433 then
18:45you're probably using a Microsoft SQL
18:48Server many of us start on the help desk
18:51to be able to provide support for our in
18:53users and one way that we're able to
18:55view the remote desktop of those devices
18:58is through the use of RDP or the remote
19:01desktop protocol RDP uses by default TCP
19:04port
19:053389 to be able to view that remote
19:08desktop the remote desktop protocol is
19:11commonly associated with a service
19:13that's running on a Windows device but
19:15fortunately there are many clients that
19:17can use RDP to connect to those windows
19:20devices so it's not unusual to find RDP
19:23clients for Windows Mac OS Linux iPhone
19:27Android and many other op operating
19:29systems there are many different
19:31protocols used for voice over IP one of
19:34the most popular is sip this is the
19:37session initiation protocol and it
19:39commonly uses TCP Port 5060 and TCP Port
19:435061 sip is commonly used as the control
19:47protocol that we use when we pick up the
19:49phone we dial the number it initiates
19:51the phone call and then when the phone
19:53call is over it disconnects the session
19:56you might also see sip being used for
19:58extend iions of Voiceover IP that
20:00provide video conferencing instant
20:02messaging and even file transfers all of
20:05this takes place using sip over TCP Port
20:085060 and TCP Port 5061

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