Common TCP and UDP Port Numbers (Quick Reference)

Published Jun 1, 2026

Common TCP and UDP Port Numbers

Port numbers identify which application or service should receive traffic on a host. Combined with an IP address, they form a socket: 192.168.1.1:443.

Use the Port Number Reference to search by number or service name.

Port ranges

Range	Name	Notes
0–1023	Well-known	IANA assigned; often need root to bind
1024–49151	Registered	IANA assigned applications
49152–65535	Dynamic/private	Ephemeral client ports

Essential ports every admin should know

Port	Service	Protocol	Description
22	SSH	TCP	Secure remote shell
53	DNS	TCP/UDP	Domain name resolution
80	HTTP	TCP	Unencrypted web
443	HTTPS	TCP/UDP	TLS-encrypted web
25	SMTP	TCP	Mail delivery
587	Submission	TCP	Mail client submission
3306	MySQL	TCP	MySQL / MariaDB
5432	PostgreSQL	TCP	PostgreSQL database
6379	Redis	TCP	In-memory cache (unofficial)
8080	HTTP-alt	TCP	Proxies / dev servers

TCP vs UDP

TCP — reliable, ordered delivery (HTTP, SSH, databases)
UDP — fast, no guarantee (DNS queries, VoIP, gaming, QUIC/HTTP3)

Some services use both: DNS uses UDP for queries and TCP for large zone transfers.

Official vs unofficial

Official ports are registered with IANA. Unofficial ports are community conventions (Redis 6379, MongoDB 27017) — widely used but not formally assigned.

Security tip

Close unused ports at the firewall. Scanning for open ports (nmap) is standard in security audits — know what should be listening before exposing a server.