What should Muromets do at the fork at the linux stone?

Question

linux

There are two network cards on the computer, one is connected to the router, the second to the Internet. What is the way to set up the system on debian?

Answer 1

Set up routes, obviously.
All requests to 0.0.0.0 are sent to the card that looks outside (that is, it will be the default gateway), local traffic to the internal one.