Utilore

Port Checker

Enter a domain and a port number and find out whether anything answers there from outside your network. That is the question a router setup or a firewall rule usually comes down to.

Common ports

The request goes to our server, not to a third-party service — the site you check never sees you.

How to use

  1. Enter the domain name — for example, example.com.
  2. Type the port, or press one of the common ones below.
  3. Press «Check»: open means the connection was accepted.

Good to know

What «open» and «closed» really mean

Open means our server established a TCP connection: something is listening and it accepted us. Refused means the host answered but nothing is on that port — the machine is alive. Timeout means no answer at all, which usually points to a firewall silently dropping packets rather than to a dead server. The tool reports which of the three happened, because the fix differs in each case.

Checking from outside is the whole point

From inside your own network almost everything looks open. Port forwarding on a router, a firewall rule, a cloud security group — none of them can be verified from the same side they were configured on. This check comes from a server somewhere else entirely, which is exactly the vantage point you need.

Frequently asked questions

Can I scan a range of ports?

No. Up to eight different ports per host per minute — enough to check a service, not enough to sweep a machine. This is a checker, not a scanner.

Why is a port that works for me shown as closed?

Because you are inside the network and we are not. That is usually the finding, not the error: the rule that lets you in does not let the internet in.

Which ports are worth checking?

80 and 443 for a website, 22 for SSH, 25 and 587 for mail, 3306 and 5432 for databases, 3389 for remote desktop. A database or remote desktop open to the whole internet is a finding in itself.

Is my own address involved?

No. The connection goes out from our server, so the check says nothing about your network and reveals nothing about you.

Related tools