Open Port Checker
Is a TCP port open on a public host? Common ports only. Private addresses are blocked.
Frequently asked questions
What does open, closed and timed out mean?
Open: something is listening and accepted the connection. Closed: the host answered but nothing is listening on that port. Timed out: no answer came back, which usually means a firewall is silently dropping the traffic.
How do I test port forwarding?
Make sure the service is running and listening on the port, then enter your public IP address (you can find it on the What Is My IP page) and the forwarded port. If the router forward and the firewall are set up correctly, the result is open.
Why does a port show closed when my service is running?
The check comes from the internet, not from inside your network. Common causes: the service only listens on localhost, a firewall blocks the port, the router is not forwarding it, or your ISP blocks it.
Which ports can I check?
Common TCP ports only: 21, 22, 25, 53, 80, 110, 143, 443, 465, 587, 993, 995, 3306, 3389, 5432, 8080 and 8443. UDP is not supported.
Why can some ports or sites not be tested?
Our checker runs on Cloudflare, which does not allow outbound connections on port 25 (SMTP) or to Cloudflare's own network. So port 25 cannot be tested, and neither can any site that sits behind Cloudflare. In those cases the result says so instead of reporting the port as closed.
Why are there limits?
To stop the tool being used to scan other people's servers. Private and internal addresses are blocked, only common ports are allowed, and each visitor can run 10 checks per minute.