Tài liệu Red Hat Linux Networking and System Administration P1 docx

®
PRESS
®
®
®
PRESS
Red Hat Linux Networking
and System Administration
Linux Solutions from the Experts at Red Hat
SECURITY TOOLS
INCLUDED ON CD-ROM
Collings
& Wall
Your Official Red Hat
®

Linux
®
Guide to Networking and System Administration
K
URT
W
ALL

has worked with Linux and Unix for nine years and is the
author of several other books, including Red Hat Linux 7.2 Weekend
Crash Course and Linux Programming by Example.
T
ERRY
C
OLLINGS

is the Instructional Technologist at Muhlenberg College in
Pennsylvania, where he is responsible for developing smart classroom
technologies. He is also the coauthor of the Linux Bible.
■
Plan your network, install Red Hat Linux, and get a handle on the file
system and configuration files
■

Configure TCP/IP networking, the Network File System, and the Net-
work Information System
■
Set up print services and connections to Windows and Macintosh clients
■

Monitor performance, administer users and groups, back up and restore
the file system, and install or upgrade software packages
■

Design a security plan, implement local security, set up firewalls and
proxy servers, and combat system intrusions
■

Troubleshoot file system, networking, printing, and e-mail problems

R
eviewed by the experts at Red Hat, this in-depth guide delivers all
the know-how you need to set up and manage a state-of-the-art Linux
network.
Red Hat Linux experts Terry Collings and Kurt Wall start with the

basics—network planning and Red Hat installation and configuration.
They then show you in detail how to set up network and Internet services,
from establishing a network file system to configuring mail services. Eight
chapters give you the lowdown on customizing the kernel, automating
tasks with scripting, performing backups, and more—the nuts-and-bolts
maintenance information you need to keep your system running smoothly.
And last but not least, the authors provide nearly 100 pages of proven
strategies and tips for maintaining system security.
Complete with utilities and code on CD-ROM, this official Red Hat
Linux guide is the one resource you need for a secure, high-performance
Linux network.
9 780764 536328
55999
ISBN 0-7645-3632-X
7
85555 09538
0
Proven Red Hat Linux Networking and Administration Solutions
CD-ROM INCLUDES
Code, scripts, and ex-
amples from the book
Linux networking and
administration tools,
including Ethereal,
logcheck, NET-SNMP,
Nmap, Portsentry,
Tripwire and SAINT
trial version
Plus a searchable
e-version of the book

Reviewed by the Experts at Red Hat
$59.99 USA
$89.99 Canada
£44.99 UK incl.VAT
Shelving Category
Networking
Reader Level
Intermediate to
Advanced
www.redhat.com
www.hungryminds.com
Cover design by
Michael J. Freeland
Cover photo © Hulton Getty
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Terry Collings & Kurt Wall
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Red Hat
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Linux
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Networking
and System Administration
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Red Hat
®
Linux
®
Networking and
System
Administration
Terry Collings and Kurt Wall
M&T Books
An imprint of Hungry Minds, Inc.
Best-Selling Books
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Red Hat® Linux® Networking and System Administration

Published by
Hungry Minds, Inc.
909 Third Avenue
New York, NY 10022
www.hungryminds.com
Copyright © 2002 Hungry Minds, Inc. All rights reserved. No part of this book, including interior design, cover design,
and icons, may be reproduced or transmitted in any form, by any means (electronic, photocopying, recording, or
otherwise) without the prior written permission of the publisher.
Library of Congress Control Number: 2001093591
ISBN: 0-7645-3632-X
Printed in the United States of America
10 9 8 7 6 5 4 3 2 1
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Distributed in the United States by Hungry Minds, Inc.
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LIMIT OF LIABILITY/DISCLAIMER OF W
ARRANTY: THE PUBLISHER AND AUTHOR HAVE USED THEIR BEST
EFFORTS IN PREPARING THIS BOOK. THE PUBLISHER AND AUTHOR MAKE NO REPRESENTATIONS OR
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a trademark or registered trademark of Linus Torvalds. All other trademarks are property of their respective owners.
Hungry Minds, Inc., is not associated with any product or vendor mentioned in this book.
is a trademark of Hungry Minds, Inc. is a trademark of Hungry Minds, Inc.
a3632-X FM.F 2/21/02 8:33 AM Page iv
About the Authors
Terry Collings has been working in the computer field since 1981 and has
experience in all types of operating systems and their associated hardware. He has
industry certifications in Novell, TCP/IP, MS Windows, and Unix. Terry’s full-time

job is at Muhlenberg College in Allentown, PA, where he is the school’s
Instructional Technologist. His main function in this position is assisting faculty in
the use of computer technology to augment their classroom presentations. He is
also the system administrator for the school’s online course content management
software. Terry also teaches a wide range of computer and technology-related
courses in the evenings at Allentown Business School. Terry has been a technical
editor for several Hungry Minds, Inc., books and is the co-author of the Linux Bible.
He can be reached at

.
Kurt Wall first touched a computer in 1980 when he learned FORTRAN on an
IBM mainframe of forgotten vintage; things have only gotten better since then.
These days, Kurt is a full-time Linux and Unix author, editor, consultant, and
programmer. He has written five books about Linux and Unix programming and
system administration, is working on his sixth, and is the technical editor for over
a dozen other Linux- and Unix-related titles. Currently, Kurt works from his home
in Indianapolis. He can be reached via e-mail at

.
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Credits
CONTRIBUTING WRITERS
Viktorie Navratilova
Dennis Powell
Brandon Wiley
ACQUISITIONS EDITOR
Terri Varveris
PROJECT EDITOR
Martin V. Minner
TECHNICAL EDITORS

Joel Lee
Matt Hayden
Sandra Moore
COPY EDITOR
Marti Paul
RED HAT PRESS LIAISON
Lorien Golaski, Red Hat
Communications Manager
PROJECT COORDINATOR
Dale White
GRAPHICS AND PRODUCTION
SPECIALISTS
Beth Brooks
Sean Decker
Melanie DesJardins
Jeremey Unger
QUALITY CONTROL TECHNICIANS
Laura Albert
Luisa Perez
Carl Pierce
Marianne Santy
SENIOR PERMISSIONS EDITOR
Carmen Krikorian
MEDIA DEVELOPMENT SPECIALIST
Greg Stephens
MEDIA DEVELOPMENT COORDINATOR
Marisa Pearman
COVER DESIGN
Michael Freeland
COVER PHOTO

Hulton Getty
PROOFREADING AND INDEXING
TECHBOOKS Production Services
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This book is dedicated to the victims and heroes of September 11, 2001.
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Preface
Red Hat Linux is the most popular distribution of Linux currently in use. Red Hat
Linux has shown itself to be a robust, reliable operating system that can run on a
variety of hardware, from personal computers to large mainframes. Linux in general,
and Red Hat Linux in particular, is a very powerful operating system that can be used
at the enterprise level as a full-fledged server, as well as at the workstation level for
typical user applications. For those of us dissatisfied with the reliability of other com-
mercially available operating systems, Red Hat Linux is a pleasant alternative.
How This Book Is Organized
This book is divided into five parts. Each part covers a specific area of functionality
in a typical Red Hat Linux system.
Part I — Red Hat Linux System and Network
Administration Defined
This part describes the duties of a system administrator. Chapter 1 explains some of
the more common tasks, such as installing servers and application software,
managing user accounts, and backing up and restoring files. Many more topics are
covered in this chapter. Chapter 2 details the steps involved in planning and build-
ing a network and planning for security and disaster recovery. Chapter 3 takes you
through the steps required to install Red Hat Linux on a local system as well as on
a remote system. Chapter 4 gives an explanation of the Red Hat Linux file system
and storage devices. Chapter 5, the last chapter in Part I, lists the system and
network configuration files and their uses.
Part II — Red Hat Linux Network Services

This part of the book is where you learn about the networking services available in
Red Hat Linux. Chapter 6 gives an explanation of the TCP/IP protocol suite and
how to configure it on your system. Chapter 7 tells how to configure the Network
File System (NFS) for sharing files with other Linux or Unix computers on your
network. Chapter 8 provides a description of the Network Information System (NIS)
as well as configuration instructions. If you have computers running Microsoft
operating systems, Chapter 9 is where you find instructions for connecting your
Red Hat Linux network to the Windows network. The final chapter in this part,
Chapter 10, tells you how to connect your Red Hat Linux network to computers
running the Apple operating system.
ix
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Part III — Red Hat Linux Internet Services
Internet services are somewhat different from network services used on an internal
network. Chapter 11 begins this part by explaining Internet services, and includes a
discussion of the xinetd and TCP wrappers configuration files.A fundamental part of
using the Internet is the ability to enter a domain name and have it converted into
an IP number that is the actual address of a computer. The name-to-number conver-
sion is done by the Domain Name System (DNS), which is covered in Chapter 12.
Chapter 13 describes the File Transfer Protocol (FTP) and gives installation and con-
figuration instructions. Sending and receiving e-mail has become so common that
it’s hard to remember the time before we had it. Chapter 14 explains mail services
and its configuration. Last, but not least, you find an explanation of setting up a
Web server. Chapter 15 covers Apache, one of the most popular Web servers in use.
Part IV — Red Hat Linux System Maintenance
The goal of this part of the book is to provide a fundamental understanding of the
tasks required to maintain your system and ensure that it runs optimally. Chapter 16
explains the Red Hat Network, a service available from Red Hat that you can use to
keep your system current. You can register your systems with Red Hat and then
receive notifications of updated or new software that can be installed. Chapter 17

discusses upgrading and customizing the kernel for your specific needs. Chapter 18
tells you how to use the command line to perform all of your system administrative
tasks. If you want to use scripts to automate some of your work, Chapter 19 is where
you find out how to do it. Chapter 20 deals with monitoring the performance of your
system. Creating users and groups is a basic part of system maintenance, and
Chapter 21 describes this process. Chapter 22 details the steps necessary to back up
your file system and use the backups to restore your system. The final chapter in this
part, Chapter 23, gives instructions on installing and upgrading software packages.
Part V — Security and Problem Solving
A critical area of concern for system administrators is maintaining a secure system.
Most of the chapters in this part deal with security, beginning with Chapter 24,
which covers security basics. Chapter 25 addresses local, or host-based, security. In
Chapter 26 you find an explanation of firewalls and Internet security and the risks
you may encounter from outside connections. Chapter 27 looks at ways to monitor
a Red Hat Linux system for attempted, potential, and actual security compromises
using the tools available in a standard Red Hat Linux installation. The last chapter
in this part, Chapter 28, lists problems you may encounter during normal operation
of your system and the steps to take to solve the problems discussed.
x Preface
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How to Use This Book
Our intention for this book is to cover the Red Hat Linux operating system in
enough detail to provide the answers that you need. The book is divided into the
parts previously discussed to make it easy for you to go to the specific part for the
topic you need to learn about. You can use the book as a reference for whatever
you need to know about a particular topic.
Using this book’s icons
Watch for the following margin icons to help you get the most out of this book:
Tips provide special information or advice.
Caution icons warn you of a potential problem or error.

This icon directs you to related information in another section or chapter.
A Note highlights an area of interest or special concern related to the topic.
This icon points you toward related material on the book’s CD-ROM.
Preface xi
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