Nmap ("Network Mapper") is a utility for network exploration or
security auditing. It may as well be used for tasks such as network
inventory, managing service upgrade schedules, and monitoring host or
service uptime. Nmap uses raw IP packets 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 scans large networks,
and works fine against single hosts.
