Port Number Lookup (TCP/UDP Ports List)
Look up what a TCP or UDP port is used for, or find the port of a service: 150+ common ports with their IANA registration, searchable by number, range or name.
Any program can listen on any port; the list says what a port is normally used for, not what is running on a particular machine.
| Port | Protocol | Common use | IANA service | Status |
|---|---|---|---|---|
| 22 | TCP | SSH, SFTP and SCP | ssh | IANA registered |
Network services listen on numbered ports: web servers on 80 and 443, SSH on 22, databases on 3306 or 5432. This lookup covers more than 150 ports you are likely to meet in firewall rules, server logs and router settings. Search by number, by range such as 1-1024, or by name such as rdp or postgres, and see the common use next to the official IANA service name — including the well-known cases where everyday use differs from the registration.
How to use this tool
- Type a port number, a range like 1-1024, or a service name.
- Optionally limit the search to TCP or UDP.
- Read the common use, the IANA service name and whether the use is official.
- Use the range class to tell system, registered and dynamic ports apart.
Formula
System ports 0–1023 · Registered ports 1024–49151 · Dynamic (ephemeral) ports 49152–65535
IANA keeps the Service Name and Transport Protocol Port Number Registry (RFC 6335). Registration is a convention, not a rule: Oracle's listener on 1521 and Kubernetes on 6443 are widely used although IANA lists other services there. Operating systems pick temporary client ports from the dynamic range.
Example
Searching 22 shows SSH (also used by SFTP and SCP), IANA service name ssh, a system port. mysql finds 3306. The range 20-25 returns 5 ports: FTP data (20), FTP control (21), SSH (22), Telnet (23) and SMTP (25). 443 has two entries: HTTPS over TCP and HTTP/3 over UDP (QUIC).
Frequently asked questions
Which ports should I keep closed?
Expose only what a service needs. Telnet (23), SMB (445), RDP (3389), database ports and unencrypted Docker (2375) should never be open to the internet; reach them over a VPN instead.
What is the difference between TCP and UDP ports?
They are separate number spaces. TCP carries reliable connections such as HTTPS and SSH; UDP carries DNS, VoIP, games and QUIC. The same number can mean different things on each.
Why does my app use a port that IANA assigns to something else?
Developers often pick convenient numbers without registering them. As long as nothing else on the machine uses the port, it works.
Sources
Last updated:
Page address with these inputs: https://kakao.mobile/tools/port-number-lookup/
Cite or embed this tool
kakaoCalc. (2026, November 8). Port Number Lookup (TCP/UDP Ports List). https://kakao.mobile/tools/port-number-lookup/
“Port Number Lookup (TCP/UDP Ports List).” kakaoCalc, 8 Nov. 2026, kakao.mobile/tools/port-number-lookup/.
Paste this code into your page. The widget runs in your visitors' browsers, shows no ads and keeps a link back to this page. Embedding terms