Nmap

Nmap (“Network Mapper”) is a free and open source (license) utility for network discovery and security auditing. Nmap.org

This tool can be used to to obtain a network inventory, determine what ports are open on a host, what services are running on ports, the version of those services, operating system identification, and much more!

The tool is available for Windows, Linux, and Mac OSX. This post will go over a couple of useful Nmap scans and display the results. Nmap is a command-line tool but also offers a graphical application called zenmap.