space
netstat

In computing, netstat (network statistics) is a command-line tool that displays network connections (both incoming and outgoing), routing tables, and a number of network interface (network interface controller or software-defined network interface) and network protocol statistics. It is available on Unix-like operating systems including OS X, Linux, Solaris, and BSD, and is available on Windows NT-based operating systems including Windows XP, Windows Vista, Windows 7 and Windows 8.

Source: http://en.wikipedia.org/wiki/Netstat