How to check if a port is open
Check whether a TCP port is open on any host from our servers. Step-by-step, plus a free port checker and DNS lookup.
Checking whether a port is open tells you if a service is reachable at a host:port — useful for debugging a server, a firewall rule, or a newly deployed service. Here is how to test it from outside your own network.
Test from outside, not just locally
A port can be open on the machine but blocked by a firewall or security group before it reaches the internet. Checking from your own laptop only tests your local view. An external checker (like ours) connects from our servers, showing what the outside world actually sees.
What "open" means
Open means a service accepted a TCP connection on that port. Closed means the host is reachable but nothing is listening; filtered/timeout usually means a firewall silently dropped the attempt. Each tells you something different about where the problem is.
Step by step
Enter the hostname or IP and the port number (e.g. 443 for HTTPS).
Run the port check — it connects from our server, not your machine.
Read the result: open, closed, or timed out.
If it is closed or filtered, check the service is running and the firewall/security group allows the port.
Try it now — free, no signup
Use the DNS & port checker in your browser. Then, when you need it at scale with an API key and higher limits, grab the full Eveses API.