How to Use a Port Scanner to Find Network Vulnerabilities

A port scanner is a software application designed to probe a server or host for open communication ports. It acts as a digital building inspector, checking every door (port) to see if it is wide open, locked, or protected by security personnel (firewalls). Both network administrators use port scanning to secure their perimeters, and cybercriminals use it to find an entry point during the reconnaissance phase of an attack. 🛡️ How Port Scanning Works

Computers communicate over networks using two primary protocols: TCP (Transmission Control Protocol) and UDP (User Datagram Protocol). There are 65,535 available ports for each protocol, divided into ranges like standard “well-known” ports (0–1023) such as Port 80 for HTTP and Port 22 for SSH.

A port scanner sends specialized packets to these ports and analyzes the responses to determine one of three states: Best Port Scanner Tools & Techniques for Network Security