ngrep

Filter network traffic packets using regular expressions. More information: https://github.com/jpr5/ngrep.

• Capture traffic of all interfaces:

ngrep -d any

• Capture traffic of a specific interface:

ngrep -d eth0

• Capture traffic crossing port 22 of interface eth0:

ngrep -d eth0 port 22

• Capture traffic from or to a host:

ngrep host www.example.com

• Filter keyword 'User-Agent:' of interface eth0:

ngrep -d eth0 'User-Agent:'