Port scanning identifies which network ports on a server are open and accepting connections. Every service listens on a specific port — web servers on 80/443, SSH on 22, email on 25/587, FTP on 21, databases on 3306 (MySQL) or 5432 (PostgreSQL).

Unnecessary open ports expand your attack surface. Attackers scan for exposed services running outdated or vulnerable software to gain unauthorized access. Regular port scanning helps verify firewall rules and ensure only required services are accessible.

This tool checks the top 20 most commonly targeted ports on any domain or IP, reporting which are open and identifying associated services.