TCP / UDP Port Reference
Look up well-known TCP and UDP port assignments.
Overview
Type a port number or service name and the reference reports the well-known TCP/UDP port assignment - what protocol uses it, whether the registration is IANA-official or a de facto standard, and the RFC where applicable.
It's for sysadmins, network engineers, and developers writing firewall rules, security group definitions, or service configurations. Reach for it when an unfamiliar port shows up in a netstat or packet capture, or when you need to confirm whether a port is safe to repurpose for a custom service.
How it works
The data is the IANA Service Name and Transport Protocol Port Number Registry - the authoritative list maintained by the Internet Assigned Numbers Authority. Ports 0-1023 are "well-known"; 1024-49151 are "registered"; 49152-65535 are "dynamic/private" (ephemeral allocation, no central assignments).
Many de facto popular ports (PostgreSQL 5432, Redis 6379, MongoDB 27017, Elasticsearch 9200) have entries from the registry too, alongside specifics like the RFC that originally specified them.
Examples
- Common service ports:
22 SSH (RFC 4251) 80 HTTP (RFC 9110) 443 HTTPS 53 DNS (TCP+UDP, RFC 1035) - Database ports:
3306 MySQL 5432 PostgreSQL 6379 Redis 27017 MongoDB - Mail and messaging:
25 SMTP 587 SMTP submission (TLS) 993 IMAPS - Reverse lookup by name:
"postgresql" -> 5432
FAQ
What's the difference between TCP and UDP for a given port?
Some services use one (HTTP is TCP only) and some use both (DNS uses UDP for small queries, TCP for zone transfers). The registry tracks each protocol independently per port.
Can I run a service on a different port?
Yes - the IANA assignment is conventional, not enforced. Many tools default to the assigned port but accept overrides. Just be aware: firewall rules, monitoring, and clients all expect the default.
What ports should I avoid for custom services?
Anything below 1024 (privileged on Unix), anything assigned to a popular service, and anything in the dynamic/ephemeral range (49152+) that the OS might allocate for outbound connections. Pick something in 8000-9999 or 30000-40000.
Why do some ports listed conflict?
A few historical assignments overlap with later, more-common uses (port 8080 has multiple unofficial uses). The reference lists the most likely interpretation first.