Open Port Checker

How to use the port checker

1. Make sure the program that should receive connections (game server, camera, NAS) is running.
2. Enter the port number, or click one of the common ports.
3. Press Check port. We try to open a connection from our network to your public IP on that port.

The check uses your own connection. If your browser has both an IPv4 and an IPv6 address, it tests IPv4 first, because port forwarding on home routers is set up for IPv4; click the IPv6 address to test that instead. To keep the tool from being used to scan other people's networks, other addresses cannot be tested.

What the results mean

From the outside, "closed" and "filtered" cannot always be told apart, so both are shown as closed.

If a port shows closed but should be open

1. Check that the program is running and listening on that port, not only on localhost.
2. Check the port forwarding rule in your router: right port, right protocol (TCP), right local IP. See port forwarding.
3. Allow the port in the device's firewall, such as Windows Defender Firewall.
4. Check for CGNAT. If your router's WAN address differs from your public IP, your provider shares addresses and incoming connections cannot reach you. See what is CGNAT.
5. Disconnect your VPN. With a VPN, the test reaches the VPN server, not your home.
6. Ask your provider whether it blocks the port on home connections.

If a port shows open but should be closed

Remove the port forwarding rule or turn off UPnP in your router, then test again. Ports such as 3389 (Remote Desktop), 445 (file sharing) and 23 (Telnet) should never be open to the internet. See common port numbers.

Frequently asked questions

Does this check UDP ports?

No. It tests TCP, which most servers use. UDP has no connection handshake, so a closed UDP port often looks the same as an open one from outside.

Why does it test a different IP than the home page shows?

Your browser may reach websites over IPv6, while port forwarding works on your IPv4 address. The checker finds both and tests IPv4 by default.

Why can I not test another IP address?

Testing someone else's ports without permission is port scanning. We only test the connection you are using.

Is it safe to check my ports?

Yes. We make one connection attempt per port and close it immediately. Nothing is sent to the program that answers.

Last updated October 21, 2026 by the FindMyIPLocation team.