Package tcpdump

A network traffic monitoring tool

http://www.tcpdump.org

Tcpdump is a command-line tool for monitoring network traffic.
Tcpdump can capture and display the packet headers on a particular
network interface or on all interfaces. Tcpdump can display all of
the packet headers, or just the ones that match particular criteria.

Install tcpdump if you need a program to monitor network traffic.

System Administration
Command Description
tcpdump dump traffic on a network
tcpslice extract pieces of and/or merge together tcpdump files