RHCE Red Hat Certified Engineer Linux (Exam RH302)

617 Pages·2008·36.23 MB·English

by  Michael Jang

RHCE Red Hat Certified Engineer Linux Study Guide (Exam RH302), Fifth Edition

byMichael Jang

McGraw-Hill/Osborne 2007 (896 pages)

ISBN:9780072264548

With hundreds of practice questions and hands-on exercises, this authoritative guide covers what you need to know--
and shows you how to prepare--for the challenging RHCE exam (RH302).

Table of Contents

RHCE Red Hat Certified Engineer Linux Study Guide (Exam RH302), Fifth Edition

Preface

Introduction

Chapter 1
- RHCE Prerequisites

Chapter 2
- Hardware and Installation

Chapter 3
- The Boot Process

Chapter 4
- Linux Filesystem Administration

Chapter 5
- Package Management

Chapter 6
- User Administration

Chapter 7
- System Administration Tools

Chapter 8
- Kernel Services and Configuration

Chapter 9
- Apache and Squid

Chapter 10 - Network File-Sharing Services

Chapter 11 - Domain Name Service

Chapter 12 - Electronic Mail

Chapter 13 - Other Networking Services

Chapter 14 - The X Window System

Chapter 15 - Securing Services

Chapter 16 - Troubleshooting

Appendix A - Sample Exam 1

Appendix B - Sample Exam 2

Glossary

Index

List of Figures

List of Tables

List of Exercises

List of Exam Details

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Back Cover

The Best Fully Integrated Study System Available

With hundreds of practice questions and hands-on exercises, RHCE Red Hat Certified Engineer Linux Study Guide, Fifth Edition covers
what you need to know--and shows you how to prepare--for this challenging exam.

�
100% complete coverage of all objectives for exam RH302

�
Exam Readiness Checklist at the front of the book--you're ready for the exam when all objectives on the list are checked off

�
Inside the Exam sections in every chapter highlight key exam topics covered

�
Real-world exercises modeled after hands-on exam scenarios

�
Two complete lab-based exams simulate the format, tone, topics, and difficulty of the real exam

Covers all RH302 exam topics, including:

�
Hardware installation and configuration

�
The boot process

�
Linux filesystem administration

�
Package management and Kickstart

�
User and group administration

�
System administration tools

�
Kernel services and configuration

�
Apache and Squid

�
Network file sharing services (NFS, FTP, and Samba)

�
Domain Name System (DNS)

�
E-mail (servers and clients)

�
Extended Internet Services Daemon (xinetd), the Secure package, and DHCP

�
The X Window System

�
Firewalls, SELinux, and troubleshooting

About the Author

Michael Jang (RHCE, LPIC-1, LCP, Linux+, MCP) is currently a full-time writer, specializing in operating systems and networks. His
experience with computers goes back to the days of jumbled punch cards. He has written other books on Linux certification, including
Linux+ Exam Cram and Sair GNU/Linux Installation and Configuration Exam Cram. His other Linux books include Linux Annoyances for
Geeks, Linux Patch Management, and Mastering Fedora Core Linux 5. He has also written or contributed to books on Microsoft
operating systems, including MCSE Guide to Microsoft Windows 98 and Mastering Windows XP Professional, Second Edition.

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RHCE Red Hat Certified Engineer Linux Study Guide (Exam
RH302), Fifth Edition

Michael Jang

New York, Chicago, San Francisco, Lisbon, London, Madrid, Mexico City, Milan, New Delhi, San Juan, Seoul, Singapore, Sydney
Toronto

McGraw-Hill is an independent entity from Red Hat, Inc., and is not affiliated with Red Hat, Inc., in any manner. This publication
may be used in assisting students to prepare for a Red Hat Certified Engineer Exam or a Red Hat Certified Technician Exam.
Neither Red Hat, Inc., nor McGraw-Hill warrant that use of this publication will ensure passing the relevant exam. Red Hat�, Red
Hat� Linux�, Red Hat� Enterprise Linux�, RHCE, and RHCT™ are either registered trademarks or trademarks of Red Hat, Inc. in
the United States and/or other countries.

This publication is not intended to be a substitute for the Red Hat RHCE prep course, RH300.

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For the young widows and widowers, may they find the courage to face their fears, to navigate their way through the pain, and to
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About the Contributors

Author

Michael Jang (RHCE, LPIC-1, LCP, Linux+, MCP) is currently a full-time writer, specializing in operating systems and networks.
His experience with computers goes back to the days of jumbled punch cards. He has written other books on Linux certification,
including Linux+ Exam Cram and Sair GNU/Linux Installation and Configuration Exam Cram. His other Linux books include Linux
Annoyances for Geeks, Linux Patch Management, and Mastering Fedora Core Linux 5. He has also written or contributed to books
on Microsoft operating systems, including MCSE Guide to Microsoft Windows 98 and Mastering Windows XP Professional,
Second Edition.

Technical Editor

Elizabeth Zinkann is a logical Linux catalyst, a freelance technical editor, and an independent computer consultant. She was a
contributing editor and review columnist for Sys Admin Magazine for ten years. As an editor, some of her projects have included
Mastering Fedora Core Linux 5, Ending Spam, Linux Patch Management, and Write Portable Code. In a former life, she also
programmed communications features, including ISDN at AT&T Network Systems.

Acknowledgments

I personally would like to thank the following people:

� Nancy E. Cropley, R.N. (d. 2002) It's now been over five years since you've left this world, but I continue to hold your spirit in

my heart, and I hope you can still see the joy of the world through my eyes. You are my hero, even today. I hope you can see
how happy I am with Donna, but I wish I could still be with you. I will always miss you.

As a political activist, you fought for what you believed in: social justice, peace, and universal healthcare. You were never
afraid to go to jail to support your beliefs. Your example is helping me find a backbone for life.

As a nurse for the homeless, you helped so many who are less fortunate. You worked tirelessly in the clinics, in the shelters,
and on the streets. Your efforts eased the pain of so many people. And you saved lives.

As an Internet entrepreneur, you showed me how to be happy pursuing a life working from home. You made it possible for me
to have the freedom to be, instead of getting stuck in the corporate world.

Nancy, you were my partner, my lover, my soul mate. You helped me find joy in this world. I take your lessons with me. I
thank you for the best seven years of my life.

� All the incredibly hard-working folks at McGraw-Hill: Tim Green, Jennifer Housh, LeeAnn Pickrell, Lisa Theobald, Paul Tyler,

and Rebecca Plunket for their help in launching a great series and being solid team players.

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Preface

Overview

Linux is thriving. Red Hat is at the forefront of the Linux revolution. And Red Hat Certified Engineers and Technicians are making it
happen.

Even in the current economic recovery, business, education, and governments are cost conscious. They want control of their
operating systems. Linux-even Red Hat Enterprise Linux-saves money. The open source nature of Linux allows users to control
and customize their operating systems. While there is a price associated with Red Hat Enterprise Linux (RHEL), the cost includes
updates and support. Now with Xen, it's possible to set up a cluster of virtual, independent installations of RHEL (and other
operating systems) on a single physical computer. As I describe shortly, there are freely available "rebuilds" of RHEL that you can
get without support from Red Hat, with features identical for most administrators.

As this book is going to print, the New York Stock Exchange has just announced that it's moving to Linux. Major corporations,
from Home Depot to Toyota, and governments such as Brazil, the Republic of Korea, and Switzerland have made the switch to
Linux. When faced with a Microsoft audit for licenses, the Portland, Oregon, school system switched to Linux. Major movie
studios such as Disney and Dreamworks use Linux to create the latest motion pictures. IBM has invested billions in Linux -and
constantly features Linux in its advertising. HP has reported 2.5 billion dollars in Linux-related revenue in 2003, and it's still growing
today (2007). Even though Linux is freely downloadable, Wall Street Technology just reported that Linux server revenue in 2006
was about 7 billion dollars, 1/3rd that of Microsoft (up from 1/4th in 2004), and is still gaining market share. Is Microsoft Vista
motivating business to look more closely at Linux?

With the One Laptop Per Child (OLPC) initiative, a streamlined version of Fedora Core 6 will be placed in front of tens (or possibly
hundreds) of millions of students worldwide. These students will learn Linux first. And Red Hat Enterprise Linux 5 is based on
Fedora Core 6.

Security is another reason to move toward Linux. The U.S. National Security Agency has developed its own version of the Linux
kernel to provide context-based security; RHEL has incorporated many of these improvements.

While there are Linux distributions available from a number of companies, Red Hat is far and away the market leader. Novell's
acquisition of SUSE hasn't made a dent. Based on 2006 sales, Red Hat has apparently shrugged off the challenge of Oracle Linux
(which is another "rebuild" of Red Hat Enterprise Linux). Incidentally, the RHCE was named #1 in CertCities.com's list of hottest
certifications for 2006. Therefore, the RHCE provides the most credibility to you as a Linux professional.

The RHCT and RHCE exams are difficult. Available historical data suggests that less than 50 percent of first-time candidates pass
the RHCE exam. But do not be intimidated. While there are no guarantees, this book can help you prepare for and pass the Red
Hat Certified Technician and Red Hat Certified Engineer exams. And these same skills can help you in your career as a Linux
administrator. Just remember, this book is not intended to be a substitute for Red Hat prep courses that I describe shortly.

To study for this exam, you should have a network of at least two Linux or Unix computers. (It's acceptable if these computers are
on virtual machines such as VMware or Xen.) You need to install RHEL on at least one of these computers. That will allow you to
configure Linux and test the results. After configuring a service, especially a network service, it's important to be able to check
your work from another computer.

On the Job�
A "rebuild" is software that is built by a third party from the same source code as the original "build." On the
other hand, a "clone" is built from different source code.

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Getting Red Hat Enterprise Linux

The Red Hat exams are based on your knowledge of Red Hat Enterprise Linux. When you take the RHCE exam, it'll be on a
"standard" PC with Intel 32-bit (or compatible) personal computers. The CPU should have a speed of at least 700MHz, and the PC
should have at least 256MB of RAM. As Red Hat Network updates are not explicitly listed as a requirement in the Red Hat Exam
Prep guide, a "trial" subscription or a rebuild distribution is probably sufficient. If you want a full subscription, which can help you
test features associated with the Red Hat Network, the price depends on your hardware and the amount of support you need. I've
emphasized Red Hat solely to focus on distributions that use Red Hat source code, including the "rebuilds" described in this
section (and more).

With Red Hat Enterprise Linux 5, Red Hat has modified its offerings into two categories:

� RHEL Server includes varying levels of support for entry-level to high-end and mission-critical systems.

� The RHEL Server Advanced Platform supports unlimited virtualized guests, virtualized storage, high-availability clustering

and failover, with support for more than two CPUs.

� RHEL Server subscriptions are available for IBM System Z mainframe systems on a per-processor basis.

� RHEL Server subscriptions are also available for High Performance Computing clusters.

� RHEL Desktop includes varying levels of support suitable for desktop computers and workstations. There are different options

available for systems with one or more CPUs.

If you want to prepare for the RHCE exam with the official RHEL 5 server operating system, trial subscriptions are available
(www.redhat.com/en_us/USA/home/developer/trial/). While they only support updates for 30 days, updates can also be tested
using the mirror repositories associated with rebuild distributions. And you can download the same operating system (for the trial
period) from the same sources as paying Red Hat users.

But you don't have to pay for the operating system or settle for a "trial subscription" to prepare for the RHCE exam. There are a
wide variety of efforts to create "rebuilds" of Red Hat Enterprise Linux. The source code for almost all RHEL RPM packages is
released under the Linux General Public License (GPL) or related licenses. This gives anyone the right to build Red Hat Enterprise
Linux from the Red Hat released source code.

The source code is released in Source RPM package format, which means the RPM packages can be built using the rpm
commands described in Chapter 5. The developers behind rebuild distributions have all revised the source code to remove Red Hat
trademarks. Most, like CentOS-5, are freely available; others, like Oracle Linux, require a subscription.

You can select and download the rebuild that most closely meets your needs. I have tried several of the rebuilds, including those
developed by Community Enterprise Linux (CentOS), Scientific Linux, and Lineox. All have proven reliable. In fact, they are so
popular, some suggest that it has led to the demise of the Fedora Legacy project, which supported older versions of Fedora Core
until December of 2006.

The rebuilds of RHEL are freely available; however, you should have a high-speed Internet connection. While these rebuilds do not
use 100 percent RHEL software, I have not seen any difference that would impair your ability to study for the Red Hat exams.

� Community Enterprise Linux The Community Enterprise Operating System (CentOS) rebuild developed by the group at

www.centos.org appears solid to me. This group probably has the largest community (or at least gets the most publicity)
among the rebuilds.

� Scientific Linux Formerly known as Fermi Linux, it includes a lot of intellectual firepower associated with the Fermi National

Accelerator Lab as well as CERN, the lab associated with Tim Berners-Lee, the person most commonly credited with the
invention of the World Wide Web.

� Lineox Lineox is based in Finland and offers priority updates for a fee. It may be especially interesting for people in the

European Union, as their prices are in Euros. You can find out more about Lineox at www.lineox.net.

Alternatively, you can work from RHEL Desktop, if you're willing to install additional services from the source code. For more
information on installing packages from source code, see Chapters 1, 5, and 8. Using the techniques described in Chapter 5, you
can download the Red Hat Enterprise Linux Source RPMs at ftp.redhat.com, process them into binary RPMs, and then install
them on your computer.

For the RHCE exams based on Red Hat Enterprise Linux 5, you can probably also work from Fedora Core 6, as RHEL 5 is based
on this Red Hat community distribution.

On the Job�
Oracle Linux has tried to undercut Red Hat by developing their own rebuild of Red Hat Enterprise Linux. Their
subscriptions cost less at what I presume are similar support levels. As I have not tried Oracle Linux, I do not
know if you get the same level of knowledge that you would get from Red Hat engineers.

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In This Book

The Red Hat RHCT and RHCE exams are designed to test candidate qualifications as Linux systems technicians and engineers. If
you pass either of these exams, it's not because you've memorized a canned set of answers-it's because you have a set of Linux
administrative skills and know how to use them under pressure, whether it be during an exam or in a real-world situation.

While this book is organized to serve as an in-depth review for the RHCT and RHCE exams for both experienced Linux and Unix
professionals, it is not intended as a substitute for Red Hat courses, or more importantly, real-world experience. Nevertheless,
each chapter covers a major aspect of the exam, with an emphasis on the "why" as well as the "how to" of working with and
supporting RHEL as a systems administrator or engineer. As the actual RHCT and RHCE Exam Prep guide
(www.redhat.com/rhce/examprep.html) changes with every release of RHEL (and even sometimes between releases), refer to the
noted URL for the latest information. (Throughout the book, I often refer to the RHCT and RHCE Exam Prep guide as the Red Hat
Exam Prep guide, even though there are Red Hat exams for certifications other than the RHCT and RHCE.)

Red Hat says it's important to have real-world experience to pass their exams, and they're right! However, for the RHCT and RHCE
exams, they do focus on a specific set of Linux administrative skills, as depicted in the Red Hat Exam Prep guide. This book is
intended to help you take advantage of the skills you already have-and more importantly, brush up in those areas where you may
have a bit less experience.

This book includes relevant information from Red Hat Enterprise Linux 5 (RHEL 5). There are significant changes from Red Hat
Enterprise Linux 4; As of this writing, Red Hat even offers a course detailing the differences (RHUP 304 and RHUP 305). Several
key differences between RHEL 4 and RHEL 5 include:

� A new hardware detection model. The udev system readily supports automatic mounting and configuration of a wide variety of

devices.

� Multicore support. Fundamental to effective virtualization, multicore CPUs can help multiple operating systems run

simultaneously on the same physical system. Red Hat includes Xen in RHEL 5 to take advantage of the latest multicore
CPUs.

� Logical Volume Management (LVM), version 2, which supports smoother resizing of filesystems.

� Software RAID now supports more modes, including RAID 6. The associated tool is more flexible.

� NFS supports "stateless" network and loopback images.

� yum replaces Up2Date for repository and package management as well as updates.

� The Network Manager incorporates improvements in wireless networking and more, which eases administration on the

desktop.

� SELinux is now easier to use and administer. The descriptions in the Security Level Configuration tool are improved, and

sealert -b browser can help you diagnose many SELinux-related issues.

There are many more key features; those that I believe are relevant to the RHCT and RHCE exams, as defined by the publicly
available course outlines and the Exam Prep guide, are also included in this book.

While it's a risky practice in service, it is fastest to administer RHEL during the exam by logging into the root user account. The
command prompt and PATH assume use of that account. When you're logged into the root account, you'll see a command line
prompt similar to:

[