Networking: fallback failed requests to another network interface

Question

I'm on a linux workstation behind a microsoft proxy server so I've installed cntlm to handle proxy authentication.

Now I want to add some more complexity; I want failed requests to use another network interface. Is this possible? To clarify my request:

• Start request from a client (browser, package manager, ecc...) through cntlm local proxy -> eth0 -> network proxy
• If the request is succesful: ok, end of the workflow
• Otherwise: retry the request using eth1 without passing through cntlm

Another acceptable solution is to use specific routes for intersted IPs, I tried this solution but I was not able to make it work. Requests still pass through cntlm, failing because parent proxy doesn't exist

Answer 1

using an additional network adapter do not have anything to do with cntlm. You have to configure a proper routing, add a secondary route with a higher distance. I cannot suggest you the right one, this depends on the ip address and the network you use.