Give one port (OPT1) the WAN IP?

[Fmstrat]

Ok, I have an odd one now.

Let's say I have the following scheme:

• An ISP provider router I have no admin access to
  • WAN IP: 11.11.11.11
  • LAN network: 22.22.22.0
• Behind that router is a PFSense box:
  • WAN IP: 22.22.22.31
  • LAN network: 33.33.33.0
• Behind that PFSense box is a client:
  • IP: 33.33.33.41

Now, is it possible to put the ISP provided router BEHIND the PFsense box, treating it like a DMZ (except for specific ports), AND making it think it has the public IP? So basically:

• PFSense box:
  • WAN IP: 11.11.11.11
  • LAN network: 33.33.33.0
• Behind that PFSense box is the ISP router that PFSense relays all traffic to except inbound port 12345
  • WAN IP: 11.11.11.11 (But really this is coming from PFSense)
  • LAN network: 22.22.22.0
• Behind that PFSense box is also a client that receives inbound traffic on port 12345:
  • IP: 33.33.33.41

The goal is to make the ISP router think it's on the "outside."

Thanks!

[netblues]

How does the isp router receive its ip address and gateway info?
pppoe? dhcp? static?

[Fmstrat]

DHCP. Thanks!

[netblues]

@Fmstrat So, create a separate dmz interface, with dhcp server and feed the isp router from there. This will assign whatever ip you wish to its wan interface, and also adjust routing.
Having said that, isp router have limited dhcp client capabilities and are often buggy.