TCP Port Checker
Check whether specific TCP ports are open on a host.
âšī¸ Checks up to 15 ports per request against public hosts only. A "closed" result may also mean a firewall is silently dropping the connection.
How TCP Port Checker works
How does this tool work?
For each port you list (up to 15 per check, comma-separated), the tool attempts a real TCP connection with PHP's fsockopen() against the resolved public IP, using a 3-second timeout per port, and reports open or closed along with connection time and, for common ports like 22 or 443, the associated service name.
When would I use this?
Useful for confirming a firewall rule actually took effect, checking whether a database or cache service like MySQL or Redis is reachable from outside before digging into application-level connection errors, or verifying a newly opened port on a VPS.
What does 'closed' actually mean here?
A closed result can mean two different things - the target actively refused the connection, or a firewall silently dropped the packets and the check simply timed out after 3 seconds - and from outside, both look identical, so this tool can't tell a hard refusal apart from a filtered port. Only public IP addresses can be scanned; anything resolving to a private or reserved range is rejected before any port is touched.