Common Ports Reference

Searchable reference of 55+ common TCP/UDP ports with service names

What is it and how does it work?

Network ports are 16-bit numbers (0–65535) that identify specific processes or services on a networked host. When your browser connects to a web server, it connects to port 80 (HTTP) or port 443 (HTTPS). When you SSH into a server, you connect to port 22. Knowing which port a service uses is essential for configuring firewalls, troubleshooting connectivity, setting up servers, and understanding network traffic. The Internet Assigned Numbers Authority (IANA) maintains the official registry of port assignments.

Port numbers are divided into three ranges: well-known ports (0–1023), assigned by IANA and requiring administrator privileges to bind to on most operating systems; registered ports (1024–49151), registered with IANA for specific applications; and dynamic/ephemeral ports (49152–65535), used temporarily by client operating systems for outbound connections. This tool lets you look up any port number to see what service it's assigned to, or search by service name to find its port.

Common use cases

• Firewall rule configuration: before opening a port on your firewall, look up what service uses it — port 3306 is MySQL, 5432 is PostgreSQL, 6379 is Redis — to ensure you're exposing only what's intended.
• Port conflict diagnosis: if a service fails to start with "address already in use", find which service typically uses that port and check if that service is already running on your system.
• Security audit: scan your firewall rules and look up each open port to verify you haven't accidentally left developer tools (like 8080, 3000, 4200) exposed on production servers.

Frequently asked questions

What is the difference between TCP and UDP ports?

TCP (Transmission Control Protocol) is connection-oriented — it guarantees delivery and ordering, making it suitable for HTTP, SSH, FTP, and most application protocols. UDP (User Datagram Protocol) is connectionless and faster but unreliable — used for DNS (port 53), DHCP (67/68), NTP (123), and streaming media where speed matters more than guaranteed delivery. Both protocols use the same 0–65535 port range independently.

Why do well-known ports require root/administrator access?

UNIX and Linux operating systems restrict binding to ports below 1024 to the root user or processes with the CAP_NET_BIND_SERVICE capability. The rationale is that well-known ports represent trusted services — if any process could bind to port 80 or 443, a malicious user could intercept web traffic. Windows has a similar restriction but it's less consistently enforced.

What are the most commonly scanned ports for security purposes?

Penetration testers and attackers typically scan port 22 (SSH), 23 (Telnet), 25 (SMTP), 80 (HTTP), 443 (HTTPS), 3306 (MySQL), 3389 (RDP/Windows Remote Desktop), 5432 (PostgreSQL), 6379 (Redis), and 8080 (HTTP alt). Running services on these ports without authentication or with default credentials is a common security vulnerability.

What is port forwarding and when is it needed?

Port forwarding (NAT port mapping) redirects connections arriving at a specific port on a public IP address to a different port on a private IP address behind a router. It's needed to run a home server (game server, web server, NAS) accessible from the internet when your device is behind a NAT router. The router receives the connection on the public port and forwards it to the internal device.

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