Port Checker

What the port checker does

The tool attempts a real TCP connection from our server to the host and port you choose. If the handshake completes within three seconds, the port is reported as open along with the time it took. If the connection is refused or times out, it is reported as closed or filtered. It also shows the IP address the hostname resolved to, which is useful when you suspect DNS is pointing somewhere unexpected. The port list covers the services website owners and administrators check most often: web (80, 443, 8080, 8443), mail (25, 465, 587, 110, 143, 993, 995), remote access (22, 3389), databases (3306, 5432, 6379), DNS (53), FTP (21) and hosting control panels (2083, 2087).

How to use it

• Enter a hostname such as example.com or a public IPv4 address.
• Choose a port from the list and click Check port for a single result.
• Click Check common ports to test 80, 443, 22, 25, 587 and 3306 in one pass and see them in a table.
• Compare the result with what you expect. A database port that shows as open to the world, for example, is a finding you should act on immediately.

Only public addresses can be checked. Private ranges, loopback and link-local addresses are rejected before any connection is attempted, and only the listed ports are allowed. This keeps the tool useful for diagnostics without turning it into a general port scanner. Results are never cached, so every check reflects the server's state at that moment.

Why it matters

Half of all "the site is down" and "email is not sending" tickets come down to a port. A firewall rule blocks 443 after a server migration, a mail provider requires 587 while the hosting company only opened 25, or an SSH key stops working because the port itself is unreachable rather than the key being wrong. Testing from an outside vantage point tells you in seconds whether the problem is on the network path or inside the application.

The reverse case is just as important. Database and cache ports such as 3306, 5432 and 6379 should almost never answer from the public internet. Running a quick check against your own server is an easy way to catch an exposed service before someone else does. When we build or host a site at Digzy Technology, we lock down every port that does not need to be public and verify the result from outside the network. If you are troubleshooting a certificate on port 443, pair this with the SSL checker, or confirm what your hostname resolves to with the DNS lookup.