Network Port Reference
A quick, searchable cheat sheet for the most common TCP and UDP networking ports used in cybersecurity and IT.
| Port | Protocol | Service | Description |
|---|---|---|---|
| 20 | TCP | FTP | File Transfer Protocol (Data) |
| 21 | TCP | FTP | File Transfer Protocol (Command) |
| 22 | TCP | SSH | Secure Shell (Encrypted remote login) |
| 23 | TCP | Telnet | Unencrypted text communications (Insecure) |
| 25 | TCP | SMTP | Simple Mail Transfer Protocol (Email routing) |
| 53 | UDP/TCP | DNS | Domain Name System (Resolves names to IPs) |
| 80 | TCP | HTTP | Hypertext Transfer Protocol (Unencrypted web) |
| 110 | TCP | POP3 | Post Office Protocol (Email retrieval) |
| 143 | TCP | IMAP | Internet Message Access Protocol (Email retrieval) |
| 443 | TCP | HTTPS | HTTP Secure (Encrypted web traffic) |
| 3389 | TCP | RDP | Remote Desktop Protocol (Windows) |
| 5432 | TCP | PostgreSQL | PostgreSQL Database |
| 8080 | TCP | HTTP-Alt | Alternative HTTP port (Often used for web servers/proxies) |
What is a Network Port?
In computer networking, a port is a communication endpoint. While an IP address identifies a specific computer on a network, a port identifies a specific application or service running on that computer.
Think of an IP address as a large apartment building, and the port number as a specific apartment number. If you send a package to the building (IP), it needs the apartment number (Port) to reach the correct person (Service).
Why are ports important for cybersecurity?
Hackers use tools like Nmap to scan a target server and see which ports are "open." If a hacker sees that Port 23 (Telnet) is open, they know the server is running an outdated, unencrypted protocol that might be easily exploited. Firewalls are configured to block traffic based on these port numbers, acting as the security guard for the apartment building.