本书为管理各种类型的系统和服务器提出建议，这些建议甚至会让经验丰富的系统管理员也迫不急待地想要学习，也会让那些使用Linux的老手感到他们遇到了新的挑战。这本书总结了各种步骤，让您可以根据这些步骤，胜任无论是搭建独立的家庭办公室或者小型办公室(SOHO)网络、网站服务器和局域网服务器，还是构建负载均衡的服务器集群和基于虚拟技术的服务器整合等一系列的工作。同时您还可以从书中学到与这些任务相关的各种工具。
　　对于Unix资深用户、微软认证系统工程师(MCSE)和大型机(mainframe) 管理员来说，《Linux系统管理》是一本绝好的Linux入门指导书。对于正在从事Linux系统管理的人而言，这本书可以作为进阶指导，让您提高已有的技能，学习新知识。
　　本书包含下列专题：安装、配置、维护基于BIND的DNS服务器并为其排查错误；为中小型企业办公室搭建具有完全安全认证功能的电子邮件服务；为网站服务器从零开始安装Apache、PHP和IMySQL并进行配置；基于免费 Linux虚拟机搭建具有负载均衡功能的Apache网站服务器集群；使用Xen或者VMWare的liunx虚拟化技术在一台服务器上运行多个Linux内核，并且管理每个内核在运行时的处理器占用时间、设备使用和内存分配；创建和改写Shell脚本以便完成您的工作；使用rsync、tar、cdrecord、Amanda和 IMySQL工具进行数据备份和恢复。
　　本书为系统管理这一传统领域提供了宝贵丰富的知识和经验。在本书作者的研究过程中，他们解决了许多以前完全没有文档记录的问题。通过本书，作者将把他们的收获传授给您。

Preface
1. Requirements for a Linux System Administrator
　About This Book
　How Can We Help？
　Where Do You Start？
　Do You Need a Book？
　Who Needs You？
　What System Managers Should Know About Linux
　What's Next
2. Setting Up a Linux Multifunction Server
　Server Requirements
　Installing Debian
　Logging in Remotely
　Configuring the Network
　Changing the Default Debian Packages
　Setting Up Quotas
　Providing Domain Name Services
　Adding a Relational Database: MySQL
　Configuring Mail Securely with Postfix, POP3, and IMAP
　Putting Apache to Work

As Bill Lubanovic and I were putting the final touches on this book, I overheard a conversation between two coworkers in our Cisco lab discussing Linux. The senior networking guru of the two made an interesting remark. He said that despite all his knowledge, he felt incomplete as a professional because he had never learned Linux. A moment later he and the other gentleman turned to me and looked me square in the eyes. I smiled and went on working. .
That evening, our director of Information Technology made an offhand remark to me during a conference that struck me as unusual. He said that he wanted to learn Apache, and when I asked him why he replied, “I just want to learn it,” and left it at that.
Later in the conference, our director requested feedback from the group on a solution for patch management, explaining and using the example of rsync. He said he wanted something similar, while launching into a detailed technical discussion of incremental and cumulative patch management. I have a good working knowledge of rsync, but hadn’t heard such a detailed academic explanation of any open source tool in any forum.
In both of those cases and many others, I wished I had this book ready to hand over to highly trained and skilled people who wanted to learn Linux administration. Perhaps you have had similar experiences and wished you had a book like this one at hand. I venture to guess that conversations like the ones I’ve just described occur many times in many places daily. ..
When Andy Oram and I began discussing a Linux system administration book, we had a slightly different idea of what we wanted to accomplish. Andy talked about a book in which each chapter took users through the steps of building and deploying application servers without co-mingling detailed discussions. He suggested that the discussion reside in one place in each chapter and the technical steps in another.Later, I proposed that we make each chapter a module unto itself and let the reader complete the modules he wanted and/or needed. As this book evolved, we felt that we’d accomplished that objective. You do not have to read this book cover to cover to become a Linux system administrator. Simply start where you have the most interest. When I first started using Linux, the community consisted mostly of programmers and hobbyists. I don’t recall any discussion lists that focused on desktops or commercial applications. We logged onto the Internet by starting a daemon. We didn’t have dialers or web browsers like the ones available today. The vast majority of people I knew did their own system administration or were in some stage of learning. Reflecting on the time when we estimated that 30,000 Linux users existed on the planet, I’m amazed at how many people use Linux today and haven’t the slightest idea how to write a configuration file. Linux forums seem to be filled with people asking how to get CUPS or Samba to work. On mailing lists, people hold detailed discussions on the technical details of projects like Postfix, JBoss, and Monit.Many people still itch to learn the extensive capabilities of Linux as an application platform. If you use Linux and want to take the next step from a power user to an administrator, this book will help you make the transition. We wrote this book with you in mind.
How This Book Is Organized
Chapter 1, Requirements for a Linux System Administrator Lays out the goals of the book and what you’ll gain by reading it.
Chapter 2, Setting Up a Linux Multifunction Server Gets you started with a nearly Internet-ready server.
Chapter 3, The Domain Name System
Shows you the basics of setting up primary and secondary DNS servers.
Chapter 4, An Initial Internet-Ready Environment
Uses the ISPConfig free software configuration system to get you started with a rich set of services that you can practice while reading the rest of the book.
Chapter 5, Mail
Sets up a Postfix mail server with SASL authentication, a POP server, and an IMAP server.
Chapter 6, Administering Apache
Gives a quick run-through of the popular Apache, MySQL, and PHP combination (together with Linux, known as a LAMP server), including SSL authentication.
Chapter 7, Load-Balanced Clusters
Extends the previous chapter’s Apache configuration with IP Virtual Server and ldirectord to provide high availability.
Chapter 8, Local Network Services
Shows you how to manage users and configure common networking elements such as DHCP and gateway software on local area networks (LANs).