Port Number Lookup
Search TCP/UDP port numbers by number or service name. Covers well-known ports (0–1023) and commonly used registered ports.
| Port | Protocol | Service | Description |
|---|
Frequently Asked Questions
Well-known ports (0–1023) are assigned by IANA and reserved for system or privileged services. Examples: port 80 (HTTP), 443 (HTTPS), 22 (SSH), 25 (SMTP). Binding to these ports usually requires root/admin privileges on most operating systems.
TCP (Transmission Control Protocol) is connection-oriented and provides guaranteed delivery — used for HTTP, SSH, FTP, etc. UDP (User Datagram Protocol) is connectionless and faster but unreliable — used for DNS, VoIP, video streaming, gaming.
Yes. Port numbers are separate namespaces for TCP and UDP. Port 53 is used for DNS over both TCP (zone transfers, large responses) and UDP (most queries). A server can listen on TCP:80 and UDP:80 simultaneously.
For a typical web server: 80/TCP (HTTP) and 443/TCP (HTTPS). For SSH admin access: 22/TCP (restrict to trusted IPs). For email: 25/TCP (SMTP), 587/TCP (submission), 993/TCP (IMAPS). Always follow the principle of least privilege — only open what you need.