An IP address gets traffic to the right device; a port number gets it to the right program on that device. Ports range from 0 to 65535 and are split into three groups:
- 0–1023, well-known ports: standard services such as web and email.
- 1024–49151, registered ports: assigned to specific applications.
- 49152–65535, dynamic ports: picked temporarily by your device for outgoing connections.
The most common ports
| Port | Protocol | Service | Notes |
|---|---|---|---|
| 20, 21 | TCP | FTP | File transfer; unencrypted, use SFTP instead |
| 22 | TCP | SSH, SFTP | Secure remote login and file transfer |
| 23 | TCP | Telnet | Unencrypted remote login; avoid |
| 25 | TCP | SMTP | Mail between servers; often blocked on home lines |
| 53 | TCP/UDP | DNS | Name lookups. See what is DNS |
| 67, 68 | UDP | DHCP | Automatic local IP addresses. See what is DHCP |
| 80 | TCP | HTTP | Unencrypted web |
| 110 | TCP | POP3 | Mail download (995 with TLS) |
| 123 | UDP | NTP | Clock synchronization |
| 143 | TCP | IMAP | Mail access (993 with TLS) |
| 443 | TCP/UDP | HTTPS | Encrypted web; UDP for HTTP/3 (QUIC) |
| 445 | TCP | SMB | Windows file sharing; never expose to the internet |
| 465, 587 | TCP | SMTP submission | Sending mail from an app |
| 853 | TCP | DNS over TLS | Encrypted DNS |
| 1194 | UDP | OpenVPN | VPN |
| 1433 | TCP | Microsoft SQL Server | Database |
| 3306 | TCP | MySQL / MariaDB | Database |
| 3389 | TCP/UDP | RDP | Windows Remote Desktop; a top target for attacks |
| 5060, 5061 | TCP/UDP | SIP | Voice over IP |
| 5432 | TCP | PostgreSQL | Database |
| 5900 | TCP | VNC | Remote desktop |
| 8080, 8443 | TCP | Alternative HTTP/HTTPS | Development servers, proxies |
| 25565 | TCP | Minecraft (Java) | Game servers |
| 51820 | UDP | WireGuard | VPN |
TCP vs UDP
- TCP sets up a connection and makes sure every piece arrives in order. Used for web pages, email and file transfers.
- UDP sends packets without a connection or delivery guarantee. Faster, used for DNS, video calls, games and streaming.
A service can use the same port number on both.
Ports to keep closed to the internet
Automated scanners try these ports on every public IP all day long. Unless you know exactly why, do not forward them:
- 3389 (RDP) and 5900 (VNC): remote desktop
- 445 (SMB) and 139 (NetBIOS): file sharing
- 23 (Telnet) and 21 (FTP): unencrypted logins
- Database ports such as 3306, 5432 and 1433
To reach these services from outside, use a VPN instead.
Check whether a port is open
Our Open Port Checker tests any TCP port on your own connection from the internet.
How to see which ports are in use on your computer
- Windows:
netstat -anoin Command Prompt - macOS:
lsof -i -P | grep LISTEN - Linux:
ss -tulpn
Frequently asked questions
Which port does a website use?
443 for HTTPS and 80 for plain HTTP. Your browser adds it automatically.
Can a port be "hacked"?
A port is just a number. The risk is the program listening on it: outdated or badly configured software can be attacked through its open port.
Is it safe that port 443 is open on my router?
Only if you forwarded it on purpose to a server you maintain. By default, home routers keep incoming ports closed.