Port Scanner

A port scanner checks which TCP ports are open and accepting connections on a specified IP address or hostname.

The tool attempts TCP connections to 17 commonly used ports and reports each as open, closed, or filtered. Open ports indicate actively running services. This information is essential for auditing server security and identifying unintentionally exposed services.

Frequently Asked Questions

What is a port scanner?

A port scanner checks which TCP ports are open on a given IP address or hostname. Open ports indicate running services. For example, port 80 means a web server, port 22 means SSH, port 3306 means MySQL.

Is port scanning legal?

Port scanning your own servers and networks is legal and a standard security practice. Scanning systems you do not own without permission is illegal in most jurisdictions. This tool is intended for testing your own infrastructure.

What ports should I worry about?

Commonly dangerous open ports include 22 (SSH with weak passwords), 3389 (Windows RDP), 3306 (MySQL), 6379 (Redis), and 27017 (MongoDB). These services should never be exposed to the public internet without strict access controls.

What does it mean if a port is closed vs filtered?

A closed port means the host responded with a rejection. A filtered port means no response came back, usually because a firewall is blocking the probe. Both mean the service is not accessible, but filtered suggests active firewall protection.