When we wrote the first edition of this book (about five years ago), Linux was just beginning to prove itself in the corporate world. We hoped that Linux Administration Handbook would help spread the news that Linux was a first-tier operating system capable of matching off against offerings from Sun, HP, and IBM.

Now Linux is IBM. For anyone awaiting an unambiguous signal that the Linux waters were safe for corporate swimmers, IBM’s 2004 announcement of Linux support across its entire server line must have been quite comforting. No one was ever fired for buying IBM; these days, Linux in general is an equally safe proposition.¹

We set out to write a book that would be the professional Linux system administrator’s best friend. Where appropriate, we’ve adapted the proven concepts and materials from our popular book, UNIX System Administration Handbook. We’ve added a truckload of Linux-specific material and updated the rest, but much of the coverage remains similar. We hope you agree that the result is a high-quality guide to Linux administration that benefits from its experience in a past life.

None of the other books on Linux system administration supply the breadth and depth of material necessary to effectively use Linux in real-world business environments. Here are the features that distinguish our book:

• We take a practical approach. Our purpose is not to restate the contents of your manuals but rather to summarize our collective experience in system administration. This book contains numerous war stories and a wealth of pragmatic advice.
• This is not a book about how to run Linux at home, in your garage, oron your PDA. We describe the use of Linux in production environments such as businesses, government offices, and universities.
• We cover Linux networking in detail. It is the most difficult aspect of system administration and the area in which we think we can be of most help.
• We do not oversimplify the material. Our examples reflect true-life situations with all their warts and unsightly complications. In most cases, the examples have been taken directly from production systems.
• We cover five major Linux distributions.

Our Example DistributionsLike so many operating systems, Linux has grown and branched in several different directions. Although development of the kernel has remained surprisingly centralized, packaging and distribution of complete Linux operating systems is overseen by a variety of groups, each with its own agenda.We cover five Linux distributions in detail:

• Red Hat^® Enterprise Linux^® 4.3 ES
• Fedora^TM Core 5
• SUSE^® Linux Enterprise 10.2
• Debian^® GNU/Linux 3.2 “Etch” (testing release of 9/06)
• Ubuntu^® 6.06 “Dapper Drake”

We chose these distributions because they are among the most popular and because they represent the Linux community as a whole. However, much of the material in this book applies to other mainstream distributions as well.

We provide detailed information about each of these example distributions for every topic that we discuss. Comments specific to a particular operating system are marked with the distribution’s logo.The Organization of This Book

This book is divided into three large chunks: Basic Administration, Networking, and Bunch o’ Stuff.

Basic Administration presents a broad overview of Linux from a system administrator’s perspective. The chapters in this section cover most of the facts and techniques needed to run a stand-alone Linux system.

The Networking section describes the protocols used on Linux systems and the techniques used to set up, extend, and maintain networks. High-level network software is also covered here. Among the featured topics are the Domain Name System, the Network File System, routing, sendmail, and network management.

Bunch o’ Stuff includes a variety of supplemental information. Some chapters discuss optional software packages such as the Linux printing system. Others give advice on topics ranging from hardware maintenance to the politics of running a Linux installation.

Each chapter is followed by a set of practice exercises. Items are marked with our estimate of the effort required to complete them, where “effort” is an indicator of both the difficulty of the task and the time required.There are four levels:

• no stars—Easy, should be straightforward
• one star—Harder or longer, may require lab work
• two stars—Hardest or longest, requires lab work and digging
• three stars—Semester-long projects (only in a few chapters)

Some of the exercises require root or sudo access to the system; others require the permission of the local sysadmin group. Both requirements are mentioned in the text of the exercise.Our Contributors

We’re delighted that Adam Boggs, Bryan Buus, and Ned McClain were able to join us once again as contributing authors. With this edition, we also welcome Ben Whaley, Tobi Oetiker, Fritz Zaucker, Jeffrey S. Haemer, David Schweikert, and Scott Seidel as contributors and friends. Their deep knowledge of a variety of areas has greatly enriched the content of this book. Above all, we thank and acknowledge Lynda McGinley, who in addition to taking ownership of a substantial amount of text also worked tirelessly to organize and facilitate our contributors’ work.Contact Information

Please send suggestions, comments, and bug reports to linux@book.admin.com. We answer most mail, but please be patient; it is sometimes a few days before one of us is able to respond. Because of the volume of email that this alias receives, we regret that we are unable to answer technical questions. To get a copy of our current bug list and other late-breaking information, visit our web site, www.admin.com.

We hope you enjoy this book, and we wish you the best of luck with your adventures in system administration!

Evi Nemeth
Garth Snyder
Trent R. Hein

October 2006

Note

1. At least on servers. Today’s battleground is the desktop, a domain over which Microsoft Windows still maintains a near-lock. The outcome of that struggle remains difficult to predict. As of this writing, Windows still provides a more polished user interface. But it’s hard to argue with “free.”