Nmap is a utility for network exploration or security auditing. It supports ping scanning (determine which hosts are up), many port scanning techniques (determine what services the hosts are offering), and TCP/IP fingerprinting (remote host operating system identification). Nmap also offers flexible target and port specification, decoy scanning, determination of TCP sequence predictability characteristics, sunRPC scanning, reverse-identd scanning, and more.
You can download it from the following link: https://packetstormsecurity.com/files/download/10868/nmap-2.3BETA13.tgz
Source: https://packetstormsecurity.com/files/10868/Nmap-Scanning-Utility-2.3-BETA-13.html