#9 block an interface complete

[Jörg Schütter]

DSL is often used via pppoe and is transportet via
ppp0. The physical
connection is established via an ethernet cable and the
NIC is also
valid as a device (e.g. eth1). But there is no traffic
via eth1, all the
traffic goes via ppp0. I think it would improve the
security a little
(it is dificult to use this interface) when the traffic
from / to this
interface is dropped.

$iptables -A INPUT -i eth1 -j DROP
$iptables -A OUTPUT -o eth1 -j DROP