Network Ports and Protocols and What They’re Used For

Published October 20, 2023

With more than 65,000 port numbers in existence, a list of common networking ports is not only helpful, but necessary. Especially if you’re studying for a networking certification exam like the Network+ or the CCNA. Both of these exams will test your knowledge of common ports and their associated services.

As a component of the Transport Layer (Layer 4 in the OSI model), TCP and UDP ports are the virtual places where network connections begin and end. Port numbers allow network-connected devices to transmit data using transmission protocols. Without port numbers, network traffic would be indecipherable.

This list of common TCP and UDP ports is by no means exhaustive, but does include ports that network administrators will be expected to use in their day-to-day role.

List of Common Ports and Protocols

Port Number	Service Name	Description	Protocol
Ports 20-21	FTP	File Transfer Protocol	TCP
Port 22	SSH	Secure Shell; used for secure logins, file transfers, and port forwarding	TCP
Port 23	Telnet	Telnet protocol; used for unencrypted text communications	TCP / UDP
Port 25	SMTP	Simple Mail Transfer Protocol, used for email routing between mail servers	TCP
Port 53	DNS	Domain Name System; translates 'host names' into IP addresses	TCP / UDP
Port 69	TFTP	Trivial File Transfer Protocol	UDP
Port 80	HTTP	Hypertext Transfer Protocol; used for unencrypted web traffic	TCP
Port 110	POP3	Post Office Protocol; used to connect to a mail server to retrieve emails	TCP / UDP
Port 123	NTP	Network Time Protocol	UDP
Port 139	NetBIOS-ssn	NetBIOS Session Service	TCP / UDP
Port 161	SNMP-agents	Simple Network Management Protocol; agents communicate on this port	TCP / UDP
Port 443	HTTPS	Hypertext Transfer Protocol Secure; used for encrypted web traffic	TCP / UDP
Port 445	Microsoft DS SMB	Microsoft Directory Services; TCP used for AD and Windows shares, UDP for SMB file-sharing	TCP / UDP
Port 514	syslog	Syslog Protocol; for collecting and organizing all log files sent from various devices on a network	UDP
Port 587	SMTP	Simple Mail Transfer Protocol; used for email message submission	UDP
Port 636	LDAP / LDAPS	Lightweight Directory Access Protocol (over SSL); used to store data in the LDAP directory and authenticate users to access the directory	TCP / UDP
Port 993	IMAP	Internet Message Access Protocol; used to deliver and manage messages on email servers on behalf of email clients	TCP
Port 995	POP3	Post Office Protocol version 3 (over SSL); lets email users download messages from an email server using an email client	TCP / UDP
Port 1433	Microsoft SQL Server	Allows encrypted access to and management of databases and servers	TCP
Port 1521	Oracle Database	Oracle client apps communicate with Oracle database servers	TCP
Port 3306	MySQL	Used to connect with MySQL clients and utilities	TCP
Port 3389	Remote Desktop Protocol	Allows client device to remotely access and control a Windows desktop computer over this port	TCP
Port 5060	SIP	Session Initiation Protocol; used to signal and control communication sessions	TCP / UDP

Understanding TCP and UDP Protocols: Frequently Asked Questions

Ports and their affiliated numbers are used to identify specific applications and services. Port numbers are what allow apps on an IP network to communicate with the source and destination IP address and the transport protocol.

What is a Port Number?

Networking protocols use port numbers that are based on the type of packet being sent and/or received. A network host typically runs many software packages/processes, so when it receives a packet it looks to the port number to identify which process should get it.

How Do Port Numbers Work?

All network-connected devices are affiliated with a port that’s been assigned a number. These port numbers are standardized, and each is reserved for certain protocols.

Port identification numbers are used to ensure the correct information is being sent and received. For example, one port is used to send the packet, while another port is used to receive the data.

All port numbers target a service or application and are reserved for certain protocols.

Where Do Ports Fall Into the OSI Model?

Ports are a concept of Layer 4 — the Transport Layer. Transport protocols such as TCP and UDP indicate the port that a packet should go to.

What Are Well Known/Systems Ports?

Port numbers that fall into the category of Well Known/Systems ports include numbers between 0 and 1023. IP protocols use them for TCP, UDP, Telnet, and FTP.

These port numbers are only used by network admins, default applications, operating systems, and services. Users do not have access to this range of ports.

What are Registered Port Numbers?

After Well Known ports is the next range of port numbers, which includes ports 1024 through 49151. This range of ports is known as “Registered ports,” because they are registered with the IANA (Internet Assigned Numbers Authority).

Unlike Well Known port numbers, Registered port numbers are used by network users.

What Are Dynamic/Private Port Numbers?

The final range of port numbers fall between 49152 and 65535. Unlike Well Known or Registered port numbers, these ports can be used without any restriction.