Port Checker tests whether a specific TCP port is open and accepting connections on any server. An open port means a service is running and reachable. Use it to verify server config, test firewall rules, or troubleshoot unreachable services.
How to use this tool
Enter the hostname or IP address.
Enter the port number (80=HTTP, 443=HTTPS, 22=SSH, 3306=MySQL).
Click Check to attempt a TCP connection.
Open means the service is reachable; Closed means it's not accepting connections.
If closed when it should be open, check firewall rules and verify the service is running.
Frequently asked questions
What ports should be open on a web server?
Port 80 (HTTP) and 443 (HTTPS) for websites. Port 22 (SSH) for management, ideally restricted by IP. Database ports like 3306 should never be exposed publicly.
What's the difference between closed and filtered?
Closed means the server refuses the connection — nothing is listening. Filtered means no response at all, usually a firewall silently dropping packets. Filtered is more secure.
Why is a port closed even though the service runs?
Most common: a firewall blocking it. Check iptables/ufw on Linux. Also check if the service listens on localhost only (127.0.0.1) instead of all interfaces (0.0.0.0). Cloud providers have separate security groups too.
Is SSH port 22 safe to keep open?
It's a common brute-force target. Secure it by using SSH keys only, changing to a non-standard port, using fail2ban, and restricting to specific IPs via firewall.