I wanted to go a little bit further and install EBtables (the 2-layer filtering and routing table). The purpose of it was to only allow the minimal necessary(IPv4 and ARP). To test it I ran:
ebtables -P INPUT DROP ebtables -P FORWARD DROP ebtables -P OUTPUT DROP
Then, I tested it,
ping 18.104.22.168, and surely enough, I got a reply. I tried a couple of other combinations, checked there are no other tables, but ping still worked. If EBtables can't block/filter, it is pointless.
I am NOT trying to block ICMP, I am trying to block everything except IPv4. To test EBtables, I tried using ICMP, but it was not blocked (meaning EBtables don't work).
What am I doing wrong? (Debian Squeeze, iptables and whatnot, EBtables v2.0.9-2)