Port Scanner
Test whether common TCP ports are reachable on a hostname or IP address. Use this tool to troubleshoot firewalls, forwarding rules, and exposed services.
What Is a Port Scanner?
A port scanner checks whether specific network ports on a remote host accept connections. Each port typically corresponds to a service, such as HTTP on port 80 or HTTPS on port 443. Open ports indicate services that are reachable over the network, while closed or filtered ports are blocked by the operating system, firewall, or router.
Common Port Use Cases
Troubleshooting Services
Verify that web servers, mail servers, SSH, and other services are reachable from the internet or your internal network.
Firewall Testing
Confirm that firewall rules are correctly allowing or blocking traffic on specific ports and protocols.
Security Hardening
Identify unnecessary open ports that could increase your attack surface and should be closed or restricted.
Port Forwarding Checks
Ensure that port forwarding on your router correctly exposes internal services (such as game servers) to the outside world.
Best Practices and Limitations
- Only scan hosts that you own or have explicit permission to test.
- Results show reachability from this server's perspective and may differ from what you see on your local network.
- Some firewalls silently drop packets, which makes ports appear as "filtered" rather than clearly open or closed.
- This tool tests TCP ports only; it does not scan UDP-based services.