Check If a Port Is Open
Enter an IP or hostname and a port number to instantly see if it's open, closed, or filtered — useful for debugging firewalls, mail servers, and custom services.
Run a port check
Enter one public hostname or IP address and a single TCP port.
Firewall rule, service down, or something else?
When a connection fails, it helps to know exactly where: is the port closed by a firewall, or is the service behind it just not running? This tool checks from an external location so you see exactly what the outside world sees when it tries to reach that port.
1. Enter the hostname or IP address and the port number.
2. CloudStats attempts a connection from an external location.
3. See instantly whether the port is open, closed, or filtered.
4. Set up continuous port monitoring to get alerted if it changes state unexpectedly.
FAQ
Frequently asked questions
What's the difference between "closed" and "filtered"?
Closed means the port actively refused the connection; filtered usually means a firewall silently dropped it without a response.
Can I check non-standard, custom application ports?
Yes, you can check any port number, not just common ones like 80, 443, or 22.
Can this replace manually running telnet or nc from my terminal?
For a quick external check, yes — and unlike checking from your own machine, it confirms what's reachable from outside your network.