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I have a strange nat problem
I became the administrator of a linux gateway using firehol.
This machine is a gateway for a small subnet /28. I have some DNAT enabled for some users to connect from home to their PC-s at work. Theese users connect to one of the IP's from my subnet. If I issue an iptables -t nat -L -n I can see the rules witch DNAT the traffic from theese users with destination to the local ip-s, but at the SNAT part I see the traffic going outside only SNAT-ed to my gateways IP.
So for example: Let's say I have 188.8.131.52 for my gateway, and 184.108.40.206 a pc behind that gateway. Users from home connect to 220.127.116.11 but theese are beeing DNAT-ed at the gateway to 192.168.X.X (a pc on the network). The problem is that according to iptables everything is SNAT-ed to 18.104.22.168 (the gateways ip).
But this is not true. If I start capturing packets with tcpdump I see that traffic sourced from 22.214.171.124. And the users can connect to their pc's (they connect to 126.96.36.199 and they get replies also from 188.8.131.52).
On the inside interface of the gateway I capture packets sourced from 192.168.x.x and on the outside interface they are sourced from 184.108.40.206. So the nat is done by the gateway.
I checked iptables -t nat and iptables -t mangle but this address 220.127.116.11 doesn't appear there.
Any help would be appreciated. Where else should I check? Firehol is doing something without iptables?