Open Port Checker

Open Port Checker

Test whether TCP ports are open on a public server or IP address. Enter a hostname or IP, pick ports — 80, 443, 22 or a small range like 8000-8010 — and the tool tries to connect to each from our server, reporting open, closed or filtered with the response time.

How the check works

For every port the server attempts a TCP three-way handshake. If the target replies with SYN-ACK, a service is listening and the port is open. If it replies with a reset, the port is closed. If nothing comes back before the 3-second timeout, a firewall is probably dropping the traffic, so the port is reported as filtered. Hostnames are resolved first; addresses in private, loopback and reserved ranges are refused for safety.

Common ports

• 80 / 443 — HTTP and HTTPS web servers.
• 22 — SSH remote login; 3389 — Windows Remote Desktop.
• 25, 465, 587 — SMTP mail delivery and submission; 993 / 995 — IMAPS and POP3S.
• 3306, 5432, 27017, 6379 — MySQL, PostgreSQL, MongoDB and Redis, which should normally not be reachable from the internet.
• 8080 / 8443 — alternative web and admin ports.

Click a chip under the form to add a port quickly.

Practical uses

Confirm that port forwarding on your router works for a game server, NAS or camera; verify that a new firewall rule opened or closed a port; check that your hosting provider does not block outgoing mail on port 25; or audit that databases are not exposed. Remember that your ISP may block some inbound ports such as 25 or 80. To find a host's address first, use Website to IP.