Common TCP and UDP ports
What each well-known port is used for, which protocol it runs on and whether it is safe to open. Official assignments come from the IANA registry; unofficial but widespread uses are marked and linked to the product’s documentation.
Check if a port is open on your IP
We only check the address you are visiting from, one TCP port at a time. You cannot enter someone else’s address: this is not a port scanner.
| Port | Protocol | Service | Category |
|---|---|---|---|
| 21 | TCP | FTP | File sharing and Windows |
| 22 | TCP | SSH | Remote access |
| 23 | TCP | Telnet | Remote access |
| 25 | TCP | SMTP | |
| 53 | TCP and UDP | DNS | Other services |
| 80 | TCP | HTTP | Web |
| 110 | TCP | POP3 | |
| 135 | TCP | MS RPC | File sharing and Windows |
| 139 | TCP | NetBIOS | File sharing and Windows |
| 143 | TCP | IMAP | |
| 443 | TCP and UDP | HTTPS | Web |
| 445 | TCP | SMB | File sharing and Windows |
| 465 | TCP | SMTPS | |
| 587 | TCP | SMTP submission | |
| 993 | TCP | IMAPS | |
| 995 | TCP | POP3S | |
| 1080 | TCP | SOCKS | VPN and proxies |
| 1194 | TCP and UDP | OpenVPN | VPN and proxies |
| 1433 | TCP | MS SQL Server | Databases and caches |
| 1521 | TCP | Oracle DB | Databases and caches |
| 1723 | TCP | PPTP | VPN and proxies |
| 2049 | TCP and UDP | NFS | File sharing and Windows |
| 3000 | TCP | dev servers | Development tools |
| 3128 | TCP | Squid proxy | VPN and proxies |
| 3306 | TCP | MySQL | Databases and caches |
| 3389 | TCP and UDP | RDP | Remote access |
| 4444 | TCP | Metasploit | Other services |
| 5000 | TCP | Flask, Docker Registry | Development tools |
| 5060 | TCP and UDP | SIP | Other services |
| 5432 | TCP | PostgreSQL | Databases and caches |
| 5900 | TCP | VNC | Remote access |
| 6379 | TCP | Redis | Databases and caches |
| 8000 | TCP | Django, Python | Development tools |
| 8080 | TCP | HTTP alternate | Web |
| 8081 | TCP | Metro, alt HTTP | Development tools |
| 8443 | TCP | HTTPS alternate | Web |
| 8888 | TCP | Jupyter | Development tools |
| 9000 | TCP | PHP-FPM, SonarQube | Development tools |
| 9090 | TCP | Prometheus, Cockpit | Development tools |
| 9200 | TCP | Elasticsearch | Databases and caches |
| 11211 | TCP and UDP | Memcached | Databases and caches |
| 25565 | TCP | Minecraft | Other services |
| 27017 | TCP | MongoDB | Databases and caches |
| 51820 | UDP | WireGuard | VPN and proxies |
Why a port can look closed when your server is running
Most home networks sit behind a router doing NAT: the router owns the public address, and your computer has a private one such as 192.168.1.10. A connection from the internet reaches the router and stops there unless you add a port forwarding rule to your computer.
Many mobile and some home providers go further and use carrier-grade NAT (CGNAT): several customers share one public address, and your router itself gets an address from 100.64.0.0/10. Then no rule on your side can open a port; ask the provider for a public IP or use a tunnel or VPN service.
Even with forwarding in place, the firewall on the computer (Windows Defender Firewall, ufw, firewalld) must allow the port, and the program must listen on all interfaces (0.0.0.0), not only on 127.0.0.1.
UDP cannot be checked this way: a UDP service usually stays silent to packets it does not understand, so “no answer” means nothing. This check uses TCP only.