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Glossary Networking

Port

A port is a number from 0 to 65535 that tells a computer which program or service an incoming network connection is for.

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In more detail

An IP address gets traffic to the right machine and the port gets it to the right program on that machine. Web servers listen on 80 (HTTP) and 443 (HTTPS), SSH on 22. Ports are tied to a transport protocol (TCP or UDP), and a Firewall usually decides which ones are reachable.

Example

The address 203.0.113.5:443 means port 443 on that machine. Look any port up with the Port Number Lookup, or see Common Network Ports Cheat Sheet.

Try these tools

Port Number Lookup

Look up the standard service name for a well-known TCP/UDP port, or search ports by service name.

TCP/UDP Port Range Generator

Generate a firewall-rule-ready list of ports from single values and ranges, with automatic compression.

See also

  • Glossary TCP
    TCP (Transmission Control Protocol) is the transport protocol that delivers data reliably and in order between two programs.
  • Glossary UDP
    UDP (User Datagram Protocol) is a fast, connectionless transport protocol that sends data without guaranteeing delivery or order.
  • Glossary Firewall
    A firewall is a system that allows or blocks network traffic according to rules about addresses, ports and protocols.
  • Cheat sheet Common Network Ports Cheat Sheet
    The port numbers behind the web, mail, SSH, DNS and databases, with TCP or UDP.
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