Policy Routing Using Linux

Linux machines, with their low cost and practically infinite configurability, work fantastically as specialized network nodes like routers and firewalls. Matthew Marsh has done a lot of research into the applicability of Linux as a router operating system--specifically to unusually complex IPv4 routing requirements--and has compiled his findings into Policy Routing Using Linux. It's a rich read for anyone interested in working with iproute2 or the Routing Policy Database (RPDB). In fact, many of the concepts Marsh discusses are applicable to routers generally; you'll find this book conceptually helpful (if not practically so) even if you do your policy routing on other kinds of equipment.

As policy routing is not a fundamental concept you must understand in order to interconnect networks, this is not an introductory text. Marsh assumes knowledge of IP addressing and routing concepts, and some familiarity with access control and packet filtering. Given that base, the author explores policy routing capabilities and limitations with great enthusiasm. He typically fills a couple of pages with conceptual text and occasional diagrams, and then jumps to examples. These alternate between command and configuration-file listings with illuminating commentary. Special topics, such as the ability of Linux's policy routing utilities to interact with dynamic routing protocols, are dealt with adequately in sidebars. --David Wall

Topics covered: The application of policies to IPv4 and IPv6 routing problems, with specific solutions outlined for the Linux operating system. Detailed coverage goes to iproute2 and the Routing Policy Database (RPDB). Examples are numerous and valuable.