ngrep
Filter network traffic packets using regex. tldr-pages
On several platforms
Several platforms
Capture traffic of all interfaces
ngrep -d anyIdentifyCapture traffic of a specific interface
ngrep -d eth0IdentifyCapture traffic crossing port 22 of interface eth0
ngrep -d eth0 port 22IdentifyCapture traffic from or to a host
ngrep host www.example.comIdentifyFilter keyword 'User-Agent:' of interface eth0
ngrep -d eth0 'User-Agent:'Identify