Server Tuning?

Question

linux

Please explain, there is a task:
Given:
There is an Internet wire, there is a server (a computer with two network cards and vpn), a router, a switch and many computers!
Task:
It is necessary that the Internet be connected to the server with VPN, then from the server to the router, from another network card, then from the router to the switch (all this from cables) and from the switch to all other computers!
The problem is that the server sees the Internet on one network card, but does not distribute it to the router from the second card ... How to be? How to do everything right? Tell me pls!

Answer 1

The server must have a virtual router, such as Untangle NG Firewall, or you need to configure iptables and turn this server into a router by itself. But how would it then turn out to be a security hole. the piece of iron on which you have a potential payload looks directly into the Internet. What prevents to put a router before the server? It seems to me that there is a fundamental error in the architecture of the network.