How to use the port checker
- Enter a hostname (like example.com) or an IP address.
- Enter the port number you want to test, or tap one of the common-port buttons to fill it in.
- Press "Check port".
- Read the result: whether the port is open or closed, the resolved IP address, and the response time in milliseconds.
What the common ports are for
| Port | Service |
|---|---|
| 80 | HTTP — standard, unencrypted web traffic. |
| 443 | HTTPS — encrypted web traffic used by most modern sites. |
| 22 | SSH — secure remote command-line access to servers. |
| 21 | FTP — file transfer between a client and a server. |
| 3389 | RDP — remote desktop access on Windows machines. |
Why open and closed both matter
An "open" result means the host answered the connection attempt on that port, which is what you want to see when a web server, mail server or remote desktop should be reachable. A "closed" or "filtered" result means nothing answered — either the service is down, the port is blocked by a firewall, or the host is simply not listening there.
This makes the checker useful in two directions. If a service you host is not working for customers, you can test the port to see whether it is reachable from the outside. If you are securing a server, you can confirm that ports you do not use are closed rather than left open to the internet.
A note on the response time
The milliseconds value shows how long the connection check took to complete, not how fast the service itself responds to real requests. It is a useful rough gauge of network distance between you and the host, but a busy application behind an open port can be slow even when the port check itself is quick.
Checking a service before you rely on it
If you are setting up a website, game server or remote desktop, running a port check right after you finish is the fastest way to confirm the outside world can reach it. Test from a normal internet connection rather than from the same machine that hosts the service, since local checks can succeed even when the port is actually blocked at the network edge. Re-check after any firewall or router change so you know the rule took effect the way you intended.