Book Review: Linux Routers - A Primer for Network Administrators, 2nd Ed.

Title: Linux Routers - A Primer for Network Administrators, 2nd Ed.Author: Tony MancillPublisher: Prentice Hall PTRISBN: 0-13-009026-3

According to its preface, Linux Routers is a howto book describing different router configurations, as well as a guide to running Linux in a production environment with all the nontechnical details that go along with it. The book covers the deployment of a Linux router--from picking the hardware to maintaining the system once it is in place--and provides philosophical as well as technical information.

Tony Mancill, the book's author, has has been running Linux in corporate production environments since 1996 and has worked as a UNIX systems administrator and systems programmer in several large IT shops. He also is a volunteer developer for the Debian project. The router configurations detailed in the book are ones that he has personally set up and maintained over the years.

Linux Routers contains 11 chapters, and seven chapters deal with specific router configurations deployed in production environments. The configurations covered include routing between two separate subnets, extranet routing, frame relay routing, tunneling routers and routing to the Internet. The book's five appendices provide useful internet links for additional reading, explain the building of the Linux kernel, discuss testing strategies and the ethics of being a network administrator, and present the GNU GPL. The book also contains a glossary, bibliography and index.

Each chapter on router configuration begins with an introduction of what tasks the router needs to accomplish, followed by the specific kernel options or software packages required for that task. Any hardware needed for the router also is introduced. Next come step-by-step instructions for configuring the Linux kernel and discussions of troubleshooting procedures. Illustrations and tables are provided to clarify the material presented. There is also information on utilities or diagnostic applications useful in specific situations.

The instructions for kernel configuration in each chapter are targeted to the 2.4 series kernels, but some information in the book that deals with earlier kernels. The book's instructions for loading software packages are targeted for Debian's distribution but are flexible enough to be adapted to other distributions. There are also specific instructions for configuring the Linux Router Project's distribution for several of the router scenarios presented in the book.

In addition to router configuration, the book deals with choosing PC hardware, how to make configuration changes in order minimize the chances of taking the network down, configuration back-up and recovery and network security. An introduction to routing basics in Linux is offered, as are explanations of specific hardware used for routing. The book also provides many pointers to additional information on a broad range of topics.

With over 100 more pages than the first edition of the book, changes in this edition of Linux Routers include targeting the 2.4 series kernels, the addition of a chapter dealing with tunneling routers and virtual private networks, information on IPv6 and more coverage of useful utilities and diagnostic tools. A chapter was also added that contains instructions for configuring the 2.2 series kernels.

Mr. Mancill advocates using Linux for routers based upon its flexibility and maintainability in addition to its cost benefits. The router configurations in the book cover a variety of real-world situations and illustrate his point well. Mr. Mancill includes explanations of what has worked for him over the years, as well as mistakes he has made and their resolutions.

Linux Routers provides a well-rounded discussion of using Linux in a variety of routing situations. Instead of simply dealing with router software configuration, the book touches on all the steps needed to put a system in place, configure it and then maintain it. While routing itself is a very technical subject, the book tries to provide understandable explanations accompanied by illustrations to help readers unfamiliar with it. Each chapter is self-contained, so readers can easily find the material that deals with their situation.

Ralph Krause (www.netperson.net/~rkrause) is a freelance programmer, writer and web site designer from Michigan. He has been writing about Linux since 1999.