Netstat

The Netstat is a command line tool that displays network connections, routing tables and a number of network interfaces. It is also used for finding problems in the network and to determine the amount of traffic on the network as performance measurements.Established connections will also list the IP address (potentially an attacker's) that the machine is connected to. It helps you quickly identify any suspicious network behavior on the machine and help point you in the right direction to files and connections that may require additional investigation.