I have a STUN service running on the same machine that is the gateway for the LAN, I would like the results from the STUN service be the same for both internal and external machines. Currently since the masquerading is done in the postrouting rule when the packets leave the gateway the STUN server will just see the LAN IP/port instead of the natted ip/port.
eth1 (lan): 10.0.0.1/32 eth0 (wan): 126.96.36.199/31 iptables -A POSTROUTING -t nat -o eth0 -j MASQUERADE iptables -A INPUT -p udp -d 188.8.131.52/31 --dport 3701 -j ACCEPT
When a LAN machine with IP 10.0.0.2 contacts the STUN service at 184.108.40.206 the packets get through but the STUN service see that the packet gets sent from 10.0.0.2.
How can I get the NAT translation to occur before the packet arrive to the STUN service and that the response back from the STUN service won't be from 10.0.0.1 but rather the 220.127.116.11 used when contacting the service?