UPDATED ON: May 23, 2012
Free and Open source Network Mapper utility
Nmap ("Network Mapper") is used for network exploration or security auditing. Many systems and network administrators also find it useful for tasks such as network inventory, managing service upgrade schedules, and monitoring host or service uptime. Nmap uses raw IP packets in novel ways to determine what hosts are available on the network, what services (application name and version) those hosts are offering, what operating systems (and OS versions) they are running, what type of packet filters/firewalls are in use, and dozens of other characteristics.
RELATED TOPICSDownload Nmap Security Scanner host monitor ip packets network inventory Network Mapper Nmap Nmap Security Scanner packet filters security auditing service uptime