Now that the Gateway server and the Intranet server have been fully configured to support the various services, we need to put them all together. Please refer to the article Plan of Action, page 102, and look up the network-topology diagram. According to it, the Gateway server and the Intranet server are to be put on a separate physical Ethernet segment, which is independent of the main LAN.

The Intranet server is a multi-homed machine with eth1 connected to the internal LAN. We shall look at this in two parts—the physical connection and the network configuration that includes NAT.
Physical connections

Gateway server to Intranet server

1. Get an eight-port hub and two patch cords

2. Connect the internal network interface (eth1: 192.168.0.1) of the Gateway server to the hub using the first patch cord.

3. Connect the external network interface (eth0: 192.168.0.2) of the Intranet server to the hub using the second patch cord.

You should not connect other workstations or servers to this network—don’t plug another box on this hub. You could also avoid a hub and use a null cable instead, and connect the two servers back to back.

Intranet server to LAN

Connect the internal interface of the Intranet server (eth1: 192.168.1.1) to the hub/switch of your internal LAN. All the other hosts on the LAN should be plugged into the same hub/switch and not to the one connecting the Gateway and the Intranet server.

The physical connections are in place. Try pinging 192.168.0.2 (Intranet) from 192.168.0.1 (Gateway). If the Internet link is up you could try pinging some public IP like dns.vsnl.net.in from the Intranet server to check whether NAT on the Gateway is working.

Shanker Balan is a technology research consultant with Exocore Consulting