Nmap 6.45

Nmap ("Network Mapper") is a free and open source (license) utility for network exploration or security auditing. Plenty of systems and network administrators also find it useful for tasks such as network stock, managing service upgrade schedules, and monitoring host or service uptime.

Nmap makes use of raw IP packets in novel ways to decide 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 jogging, what type of packet filters/firewalls are in use, and dozens of other characteristics.
It was designed to quickly scan huge networks, but works fine against single hosts.Download