Ports and Protocols Flashcards

Learn the ports and protocols on the CompTIA Network+ exam with spaced repetition, the method behind Anki. Cards you find hard come back sooner and cards you know come back later, so you spend your time on what you haven't learned yet. Your progress is saved on this device. New to these ports? Start with the illustrated guide.

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Network+ core Beyond Network+

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Every port in the deck

The Network+ core deck is the complete list from CompTIA Network+ N10-009 exam objective 1.4. The Beyond Network+ deck adds ports that often come up on Security+ and CCNA, or that you'll meet in real networks. For a diagram, a real example and an exam tip for each one, see the illustrated guide.

Network+ core (N10-009 objective 1.4)

Port	Protocol	TCP/UDP	What it does
20/21	FTPFile Transfer Protocol	TCP	Transfers files. Port 21 carries commands and port 20 carries data (in active mode). Nothing is encrypted, not even passwords.Example: A web designer uploads site files to an old hosting server with FileZilla, connecting on port 21.
22	SSHSecure Shell	TCP	Encrypted remote command-line access to servers and network devices.Example: An admin runs ssh admin@192.168.1.1 to configure a router from the command line.
22	SFTPSecure File Transfer Protocol	TCP	Encrypted file transfer that runs over SSH, which is why it shares port 22.Example: A developer copies a backup to a Linux server with sftp user@server, which travels inside SSH.
23	Telnet	TCP	Remote command-line access with no encryption. Replaced by SSH.Example: An old switch is managed with telnet 10.0.0.5, so anyone capturing the traffic can read the password.
25	SMTPSimple Mail Transfer Protocol	TCP	Sends email between mail servers.Example: Gmail's mail servers deliver your message to the recipient's mail server over port 25.
53	DNSDomain Name System	TCP and UDP	Turns names like example.com into IP addresses. UDP for normal lookups, TCP for zone transfers and large answers.Example: Typing example.com in a browser sends a DNS query that comes back with the site's IP address.
67/68	DHCPDynamic Host Configuration Protocol	UDP	Gives devices an IP address automatically. Servers listen on 67, clients on 68.Example: A laptop joins the office Wi-Fi and automatically receives its IP address, gateway and DNS server.
69	TFTPTrivial File Transfer Protocol	UDP	Very simple file transfer with no login, often used to copy configs and firmware to network devices.Example: A Cisco switch pulls a new firmware image from a TFTP server with copy tftp: flash:.
80	HTTPHypertext Transfer Protocol	TCP	Unencrypted web traffic.Example: A page loaded over http:// shows "Not secure" in the browser's address bar.
123	NTPNetwork Time Protocol	UDP	Keeps device clocks in sync.Example: Every router and server syncs its clock to pool.ntp.org, so log timestamps line up across devices.
161/162	SNMPSimple Network Management Protocol	UDP	Monitors and manages network devices. Managers poll devices on 161, devices send alerts (traps) to 162.Example: A monitoring tool polls a switch on 161 for traffic counts, and the switch sends a trap to 162 when a link goes down.
389	LDAPLightweight Directory Access Protocol	TCP (UDP also possible)	Looks up users, groups and computers in a directory such as Active Directory.Example: A web app checks a user's password and group membership against Active Directory before letting them in.
443	HTTPSHypertext Transfer Protocol Secure	TCP (HTTP/3 uses UDP)	Web traffic encrypted with TLS.Example: Online banking loads over https://, so nobody else on the network can read your account details.
445	SMBServer Message Block	TCP	Windows file and printer sharing.Example: A Windows PC opens \\fileserver\shared to reach the team's shared network drive.
514	Syslog	UDP	Sends log messages from devices to a central log server. Traditionally UDP, though TCP versions also exist.Example: A firewall sends a message about every blocked connection to a central log server for later review.
587	SMTPSSimple Mail Transfer Protocol Secure	TCP	Encrypted email submission from mail apps to a mail server. Port 465 (SMTP over TLS) is also used.Example: A mail app such as Thunderbird sends mail through smtp.gmail.com on port 587.
636	LDAPSLDAP over SSL	TCP	LDAP encrypted with TLS.Example: A VPN appliance checks staff logins against Active Directory over an encrypted LDAPS connection.
1433	SQL ServerMicrosoft SQL Server	TCP	Default port for Microsoft SQL Server databases.Example: A company's accounting app reads and writes its data on a Microsoft SQL Server database on 1433.
3389	RDPRemote Desktop Protocol	TCP (UDP also used)	Remote desktop access to Windows computers.Example: A helpdesk tech opens Remote Desktop Connection (mstsc) to work on a Windows server's desktop.
5060/5061	SIPSession Initiation Protocol	TCP and UDP	Sets up and ends VoIP calls. 5060 is unencrypted, 5061 uses TLS.Example: An office desk phone registers with the company's VoIP system and uses SIP to set up each call.

Beyond Network+ (Security+ and CCNA extras)

Port	Protocol	TCP/UDP	What it does
49	TACACS+Terminal Access Controller Access-Control System Plus	TCP	Authentication, authorization and accounting (AAA) for admins logging in to network devices. Encrypts the entire payload.Example: An engineer logs in to a Cisco router, and the router asks a TACACS+ server which commands they're allowed to run.
88	Kerberos	TCP and UDP	Ticket-based network authentication, used for Active Directory logins.Example: Logging in to a domain-joined Windows PC gets you a Kerberos ticket from the domain controller.
110	POP3Post Office Protocol version 3	TCP	Downloads email from a server to one device, usually removing it from the server.Example: An old email app downloads all new mail to one PC and deletes it from the server.
137-139	NetBIOS	TCP and UDP	Older Windows name and session services: 137 name service (UDP), 138 datagrams (UDP), 139 sessions (TCP).Example: An older Windows PC finds another computer on the LAN by its name, such as OFFICE-PC.
143	IMAPInternet Message Access Protocol	TCP	Reads email while keeping it on the server, so every device stays in sync.Example: Reading a message on your phone marks it as read on your laptop too, because both use IMAP.
179	BGPBorder Gateway Protocol	TCP	Exchanges routes between networks across the internet.Example: An internet provider uses BGP to tell the rest of the internet which IP address blocks it can reach.
500	IKEInternet Key Exchange	UDP	Negotiates the keys for IPsec VPN tunnels. Switches to UDP 4500 when NAT is in the way.Example: Before a site-to-site VPN carries any traffic, the two firewalls use IKE to agree on encryption keys.
993	IMAPSIMAP over TLS	TCP	IMAP encrypted with TLS.Example: The iPhone Mail app reads Gmail from imap.gmail.com on port 993.
995	POP3SPOP3 over TLS	TCP	POP3 encrypted with TLS.Example: An email client downloads mail from pop.gmail.com on port 995.
1701	L2TPLayer 2 Tunneling Protocol	UDP	VPN tunnel, usually combined with IPsec for encryption.Example: A Windows laptop connects to the office with the built-in L2TP/IPsec VPN option.
1812/1813	RADIUSRemote Authentication Dial-In User Service	UDP	AAA for network access such as Wi-Fi and VPN. 1812 for authentication, 1813 for accounting.Example: Joining company Wi-Fi with your work username (WPA2-Enterprise) sends your login to a RADIUS server.
3306	MySQL	TCP	Default port for MySQL databases.Example: A WordPress site stores its posts and user accounts in a MySQL database on port 3306.