Feb 2021

Here are some more great uses for tcpdump.

tcpdump -i eth0 -nn -Q in

Shows only the 'input' traffic on the specified interface

Can also use -Q out for just outgoing traffic

tcpdump -i eth0-nn igmp

Shows only IGMP traffic on the specified interface

Can be combined with -Q in/out

tcpdump -i eth0 -nn igmp -Q in