Nmap is a free tool for network exploration and security audits. The application uses low-level IP packets to determine which hosts are available in the network, which services are running and under which operating systems, as well as the type of firewalls. The program offers a variety of port scanning techniques including TCP SYN, TCP connect(), UDP, TCP ACK, TCP Window, TCP Maimon, TCP Null, FIN and Xmas, TCP with defined flags, Idle, IP protocols, FTP bounce, and the status of each service can be evaluated using one of the statuses.

An additional advantage of Nmap is the ability to inventory the network, manage update schedules and monitor hosts and service time.