On my linux firewall/router, my PREROUTING table seems to be acting funny.
I have the following 2 entries amongst others (IP's were obviously changed):
DNAT icmp -- * * 0.0.0.0/0 184.108.40.206 icmp type 8 state NEW,RELATED,ESTABLISHED to:10.0.0.2 DNAT icmp -- * * 0.0.0.0/0 220.127.116.11 icmp type 8 state NEW,RELATED,ESTABLISHED to:10.0.0.3
From my home computer, when I ping either 18.104.22.168 or 22.214.171.124, the pkts and bytes counters go up in the PREROUTING table as expected. However, when I do a tcpdump to view the forwarded packets, the pings sent to 126.96.36.199 are not be NAT'ed.
The outgoing packets leaving the firewall out eth1 are SRC: my.home.ip TO: 188.8.131.52.
When I ping 184.108.40.206, it is properly NAT'ed and the packets are sent to 10.0.0.3.
Any ideas why this is happening? What really baffles me is the fact that I know the pings are matching the iptables rules because the packet counters are increasing yet they are not being NAT'ed.