Nmap ("Network Mapper") is a console utility 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. It was designed to rapidly scan large
networks, but works fine against single hosts.
