I still don't know how to log traffic on a specific interface ( eg eth0 )

Well, RTFM. ;-) http://netfilter.samba.org/unreliable-guides/ And try the following: iptables -A INPUT -i eth0 -j LOG iptables -A FORWARD -i eth0 -j LOG iptables -A FORWARD -o eth0 -j LOG iptables -A OUTPUT -o eth0 -j LOG HTH Tobias