Free network tool

Open port checker

Find out whether a TCP service on your public address accepts an incoming connection.

Your result

Which port do you want to check?

Start your service, then enter its TCP listening port. The check uses your current IP address.

Ready

The collector checks the address it sees for your request. If you use a VPN or proxy, that may be its exit address rather than your home connection.

How it works

Check port forwarding and connection problems

A port forwarding test needs a service that is running and listening on the selected TCP port. Configure the router rule to point to that device's local IP, allow the port through its firewall, then run the check from that connection.

A reachable port confirms that a TCP connection succeeded at the time of the test. If forwarding is configured but the connection still fails, compare your router's WAN address with the CGNAT test to check for upstream NAT.

Accepted: reachable now

A service accepted the TCP connection. Check that it is the service you intended to expose.

Refused: check the service

The connection was actively rejected. Make sure your service is running and listening on the correct interface and port.

Timeout: check the route

A firewall, NAT, ISP filter or routing issue may have dropped the connection. A timeout does not prove the port is closed.

Check your router

Verify port forwarding to the correct device. If your ISP uses CGNAT, ordinary router forwarding may not be enough.

View port probe details

Run the test to see its detected details.

Common questions

Can I check another IP address?

This tool checks only the address observed by the collector from your request. It does not accept another target address.

Can it check UDP ports?

No. This check opens a TCP connection. A TCP result does not describe UDP reachability.

Does a reachable port mean it is secure?

No. It only confirms a TCP handshake at that moment. Keep the exposed application up to date and use appropriate authentication.