Currently I am using a Raspberry Pi to bridge an ethernet connected printer to wireless internet and have used DNAT successfully to give the printer internet access, manually forwarding the printer’s port 80 to the Rpi’s wlan0 interface port 80 along with other needed ports to access the printer using outside hosts. I’ve also been able to use Proxy ARP so that the printer’s static IP address is visible on the network, the Pi responding to ARP broadcasts on the printer’s behalf and proxying ARP requests for the printer. What I would like to do is combine the functionality of the DNAT approach with the IP separation provided by Proxy ARP.
The problem is that I cannot figure out how to seamlessly accomplish the needed forwarding/spoofing with the Rpi so that instead of directing requests to the Pi’s port 80, outside hosts can make requests using the printer’s IP directly even if it’s on a different subnet, say 10.1.2.254:80, to access the http page.
Is it possible to accomplish this routing in tandem with Proxy ARP? Are there other approaches that are better suited for this arrangement, or could IP aliases alongside DNAT accomplish this illusion that the printer’s IP and active ports are also present on the network/another network?