Linux Firewalls, Third Edition

Connecting Networks

Let's contrast the preceding case with the case in which you want to connect two networks. These networks could be in separate physical locations, or they could just be two separate subnets of the same network.

In this configuration, the VPN gateways have startup scripts to start IPSec services at boot time. The servers establish a secure connection with each other. Both gateways have a static route to the other gateway. From a user perspective, they don't need to do anything to communicate and share information between networks. All communication is taken care of by the VPN gateways. From the perspective of the user, it looks as though Network 2 is on the same network as Network 1. This may be a slight oversimplification, ...