I have a router with three interfaces serving two (related) companies. Each company has their own LAN interface but both share the WAN interface even though each company has a different public IP. I've set up standard NAT and incoming PAT rules and everything works just fine... EXCEPT I cannot get company1 to communicate to company2 if they use their external WAN IPs...
here's a sanitized snipped of the config:
ip address 126.96.36.199 255.255.255.240
ip address 188.8.131.52 255.255.255.240 secondary
ip nat outside
ip address 10.0.0.1 255.255.255.0
ip address 192.168.0.1 255.255.255.0
ip nat inside
ip route 0.0.0.0 0.0.0.0 184.108.40.206
ip nat inside source static tcp 192.168.0.8 25 220.127.116.11 25 extendable
ip nat inside source static tcp 10.0.0.16 25 18.104.22.168 25 extendable
If I try to connect to port 25 of company1's public IP from an internal LAN IP of company2 it doesn't work. I can connect internal 10.0.0.x and 192.168.0.x just fine, but using the other company's public IP doesn't work.
I'm guessing it's because I'm doing double NAT, but I don't know how to fix it.