tcpdump

Dump traffic on a network. More information: https://www.tcpdump.org.

tcpdump -D

tcpdump -i eth0

tcpdump -A tcp

tcpdump host www.example.com

tcpdump -i eth0 src 192.168.1.1 and dst 192.168.1.2 and dst port 80

tcpdump net 192.168.1.0/24

tcpdump -w dumpfile.pcap port not 22

tcpdump -r dumpfile.pcap