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 37	Time	Used to provide a machine-readable date and time, usually for synchronizing clocks	TCP / UDP
Port 49	TACACS	Terminal Access Controller Access-Control System	TCP / UDP
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 88	Kerberos	Used for secure network authentication, especially in Active Directory environments	TCP / UDP
Port 102	ISO-TSAP	ISO Transport Service Access Point (TSAP)	TCP / UDP
Port 110	POP3	Post Office Protocol; used to connect to a mail server to retrieve emails	TCP / UDP
Port 111	rpcbind	Portmapper service used to map RPC program numbers to network port numbers, typically used in NFS and other RPC services.	TCP / UDP
Port 123	NTP	Network Time Protocol	UDP
Port 135	DCE/RPC Endpoint Mapper	Distributed Computing Environment / Remote Procedure Call (DCE/RPC) Endpoint Mapper	TCP / 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
Ports 381 - 383	HP Performance Data Collector	Collects performance data from managed nodes	TCP / UDP
Port 389	LDAP	Lightweight Directory Access Protocol	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 464	Kerberos	Used for changing or setting passwords in Kerberos-based authentication systems, such as Active Directory	TCP / UDP
Port 465	SMTP	Simple Mail Transfer Protocol; used to securely transmit mail messages from email clients to email servers.	TCP
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 593	RPC Mapper Service	Enables secure remote connections and function execution over HTTP.	TCP / 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 691	Microsoft Exchange Routing Engine (RESvc)	Used by Microsoft Exchange servers to update routing tables for efficient message delivery.	TCP
Port 902	VMware vSphere	Used to manage your ESXi hosts and the virtual machines (VMs) that run on them	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 1194	OpenVPN	Used by OpenVPN for establishing encrypted tunnels between VPN clients and servers	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
Port 5353	mDNS	Multicast DNS (mDNS) is used for resolving hostnames to IP addresses within small networks without a local DNS server.	UDP
Port 5432	PostgreSQL	Used for communication between PostgreSQL clients and the database server	TCP
Port 5900	VNC (Virtual Network Computing)	Used for remote desktop sharing, allows a client to remotely view and control another computer's desktop	TCP
Ports 6665-6669	IRC (Internet Relay Chat)	Used for Internet Relay Chat (IRC) communications, enabling text-based communication over networks	TCP / UDP
Ports 6881-6999	BitTorrent	Used for peer-to-peer file sharing, facilitating data distribution across networks	TCP / UDP
Port 10000	Webmin	Used for remote server communication and configuration	TCP
Port 12345	NetBus	Used for remote administration; can be exploited for unauthorized access	TCP / UDP
Port 31337	Back Orifice / ncat	Used for remote control of servers by hacking tools and remote administration utilities	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/system 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?

The next range of port numbers after well-known ports 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 falls between 49152 and 65535. Unlike well-known or registered port numbers, these ports can be used without any restriction.