Donaldson R F Common Ports Lookup
Search a port number or a service name to see what it is normally used for. This is a reference list — it does not scan or connect to anything.
What port numbers mean
A port is a number from 0 to 65535 that lets one computer run many network services at once. Well-known ports (0–1023) are assigned by IANA to standard services such as HTTP (80) and HTTPS (443); registered ports (1024–49151) are assigned to specific applications; the rest are for temporary (ephemeral) connections. TCP ports and UDP ports are separate, so the same number can mean different things on each.
Port numbers are only conventions: a service can run on any port, and an open port does not tell you what is really listening. Entries marked common use are popular but not officially registered for that purpose. To close or restrict ports on your own systems, use a firewall and follow your provider’s guidance. Related: DNS lookup.