Common network ports quick reference
Below are the TCP and UDP ports you will see most often in firewalls, logs and configuration files. Most services listen on a fixed default port, so knowing the common ones lets you identify traffic at a glance.
| Port | Protocol | Transport | Purpose |
|---|---|---|---|
| 20/21 | FTP | TCP | File transfer (21 control, 20 data) |
| 22 | SSH | TCP | Secure remote login and SFTP |
| 23 | Telnet | TCP | Unencrypted remote terminal |
| 25 | SMTP | TCP | Sending and relaying email |
| 53 | DNS | UDP/TCP | Domain name resolution |
| 67/68 | DHCP | UDP | Automatic IP assignment |
| 80 | HTTP | TCP | Web pages, unencrypted |
| 110 | POP3 | TCP | Email retrieval |
| 143 | IMAP | TCP | Email synchronisation |
| 443 | HTTPS | TCP | Secure web traffic |
| 587 | SMTP submission | TCP | Email sending with authentication |
| 993 | IMAPS | TCP | Secure IMAP over TLS/SSL |
| 3306 | MySQL | TCP | MySQL database access |
| 5432 | PostgreSQL | TCP | PostgreSQL database access |
| 3389 | RDP | TCP | Windows remote desktop |
| 8080 | HTTP alt | TCP | Web proxy and dev servers |
Notes
- Well-known ports are numbered 0–1023 and assigned by IANA; anything can technically run on any port, so confirm what is actually listening.
- For unencrypted protocols such as SMTP or POP3, the secure variant usually runs on a separate port (465/587 or 995).
- UDP is connectionless and used where speed matters; services like DNS and DHCP answer on both TCP and UDP.
Frequently asked questions
- What is port 443 used for?
- Port 443 is the default port for HTTPS, the encrypted version of HTTP. It is what browsers use for most secure websites and where TLS connections terminate.
- What is the difference between TCP and UDP ports?
- TCP establishes a reliable, ordered connection and is used by most services such as HTTP, SSH and email. UDP is faster and connectionless, which suits DNS queries, DHCP and streaming.
- Which ports are considered well-known?
- Well-known ports are numbers 0–1023, assigned by IANA to standard services such as HTTP (80) and HTTPS (443). Ports 1024–49151 are registered, and 49152–65535 are dynamic or ephemeral.
- How can I check which ports are open on my machine?
- On Windows run netstat -ano. On macOS and Linux use netstat -tulnp or lsof -i. The output lists listening addresses and the program owning each port.