A free and open source tool for network discovery and security auditing
Pros & Cons:
Nmap ("Network Mapper") is a free and open source tool for network discovery and security auditing. It will scan an individual IP address or a range and report on open ports, interesting information and the likely type of device or operating system.
This tool proved invaluable in proving to a client that the IP address he claimed was a print server in fact had a PC using it.
Nmap runs on major operating systems including Windows, Mac OS X and Linux. It requires WinPcap but it is included in the Nmap suite, which also includes the graphical user intereface Zenmap and other debugging and analysis tools.
Nmap was reviewed by Gizmos Freeware on