Guides ·
How to use Port Checker
Port Checker. Is a TCP port open on a host?. No service is listening, the router is not forwarding it, or a firewall rejects it.
The short answer
To check if a port is open, enter a host and port (or pick a common one such as 22, 80, 443, 3389 or 25565): ClickZM's server tries a TCP connection and reports open, closed or filtered, with the response time and any service banner.
A browser cannot make this check itself, so ClickZM's server does it, blocks private addresses, and does not store the lookup.
How to use it
Enter the website address, domain or IP you want to check.
Click the button to run the Port Checker.
Read the results; warnings and errors are highlighted with an explanation.
Fix any issue, then run the check again to confirm.
Limits worth knowing
Why does my port show closed? No service is listening, the router is not forwarding it, or a firewall rejects it. 'Filtered' means the connection attempt timed out.
Can I scan many ports? This tool checks one port at a time to prevent abuse; private and local addresses are blocked.