Sidebar 1: Assumptions

All of the examples and code in the following sections were developed on a Linux system running Caldera OpenLinux 2.3 with the following additions.

1. I compiled kernel 2.2.12 with all of the section on “Networking Options” compiled in except for a few. Note that you can use the installed kernel 2.2.10 for most of the examples.

2. I obtained and compiled the IPROUTE2 utility by Alexey Kuznetsov version iproute2-2.2.4-now-ss990824.tar.gz -- this provided the ip utility used throughout this article.

3. I obtained and compiled ipchains version 1.3.9 for the purpose of the multiple IP masq examples and fwmark.

4. All of the IP addresses are manually added using the ip utility I actually have custom init scripts that do this, but for the examples here I will spell out the manual methods to show exactly what is being done. Without using ip, you cannot do any of the policy routing and addressing.