Network traffic monitoring with tcpdump

tcpdump is a command-line network traffic analyzer. It allows capture of network packets from a host and subsequent filtering and display.

Sample applications

Show traffic into port 2003 from a given host

sudo tcpdump -A -nn 'port 2003 and src host 10.60.35.49'

Must run as root (sudo)
-A print ASCII payload
-nn numeric IP and ports