Online port checker
Verify your server's external visibility. Test if specific TCP ports are open, closed, or filtered by your firewall from an outside perspective.
What is a port checker?
A port checker is a simple tool to check for open ports on your computer or device. It is most commonly used to verify port forwarding settings on a router.
If you are facing connection issues with a program like an email client or a web server, the required port might be blocked by your router's firewall or your ISP. This tool helps you diagnose firewall setup problems and security vulnerabilities by confirming whether a specific port is open or closed to the public internet.
For example, if you host a Minecraft server, you can use this checker to ensure port 25565 is properly forwarded so your friends can connect to your server.
Most commonly used ports
Port numbers range from 1 to 65535. The Internet Assigned Numbers Authority (IANA) defines several conventions for these ranges:
- 0 - 1023 Well-known ports (HTTP, SMTP, FTP, etc.)
- 1024 - 49151 Reserved ports for specific services.
- 49152 - 65535 Dynamic or private ports.
Well-known port list
For a complete list of all registered ports, visit the Wikipedia list of port numbers.