tcpdump

tutorial

http://openmaniak.com/tcpdump.php

list all traffic

sudo tcpdump

list all interfaces

sudo tcpdump -D

log traffic on interface eth0

sudo tcpdump -i eth0

list traffic on certain port

sudo tcpdump port 443

show ip-addresses instead of DNS names

sudo tcpdump -n

traffic from src ip on port

sudo tcpdump port 443 and src 217.149.135.12