foundations of centos linux

this print for content only—size & color not accurate trim = 7.5" x 9.25" spine = 0.000" 000 page count   CYAN   MAGENTA   YELLOW   BLACK Foundations of CentOS Linux ThE ExpErT’s VOiCE ®  iN LiNux Foundations of CentOS Linux Enterprise Linux On the Cheap Ryan Baclit, Chivas Sicam, Peter Membrey, and John Newbigin Companion eBook Available A truly free enterprise alternative to Red Hat Enterprise Linux Baclit Sicam Membrey Newbigin BOOKs fOr prOfEssiONALs BY prOfEssiONALs ® US $42.99 Shelve in Linux User level: Beginning Companion eBook See last page for details on $10 eBook version Foundations of CentOS Linux: Enterprise Linux On the Cheap Dear Reader, I’ve been using Linux for years for software development, for personal enter- tainment, and to create servers to be deployed on the network. But when asked on which distribution I always use when creating and deploying network serv- ers, I always say CentOS. With CentOS, I have all the tools that I need to do tasks with Linux, from command-line shell scripting to graphical systems adminis- tration with virtualization. The book you are holding now contains expert advice that will help you learn Linux administration with the CentOS distribution. You will be able to write shell scripts, schedule automated tasks and use the GNOME desktop. For network servers, you will learn how to properly install and configure file sharing and print servers, combine servers with directory services for unified authentication, and use virtualization to save on hardware costs. With this book, you have a concrete starting guide to learning Linux with CentOS. You will spend less time asking questions and more time to build- ing whatever you need with CentOS as you learn about it with this book. If you have plans of becoming an RHCE (Red Hat Certified Engineer), what you have learned here will give you a boost in studying review materials for the RHCE exam. I hope that you will enjoy learning Linux with CentOS and use it to create masterpiece servers with this book. Ryan Baclit THE APRESS ROADMAP The Definitive Guide to SUSE Linux Enterprise Server Pro Linux System Administration The Definitive Guide to CentOS Pro Ubuntu Server Beginning the Linux Command Line Beginning Ubuntu Linux, 4th edition Beginning SUSE Linux Foundations of CentOS Linux Beginning Ubuntu LTS Server Administration )3".        Ryan Baclit Chivas Sicam Peter Membrey John Newbigin www.it-ebooks.info www.it-ebooks.info Foundations of CentOS Linux Enterprise Linux On the Cheap ■ ■ ■ Ryan Baclit, Chivas Sicam, Peter Membrey, and John Newbigin www.it-ebooks.info ii Foundations of CentOS Linux: Enterprise Linux On the Cheap Copyright © 2009 by Ryan Baclit, Chivas Sicam, Peter Membrey, and John Newbigin All rights reserved. No part of this work may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or by any information storage or retrieval system, without the prior written permission of the copyright owner and the publisher. The Evolution Mail Client logo is a copyright of Evolution project and was printed with permission. ISBN-13 (pbk): 978-1-4302-1964-4 ISBN-13 (electronic): 978-1-4302-1965-1 Printed and bound in the United States of America 9 8 7 6 5 4 3 2 1 Trademarked names may appear in this book. Rather than use a trademark symbol with every occurrence of a trademarked name, we use the names only in an editorial fashion and to the benefit of the trademark owner, with no intention of infringement of the trademark. President and Publisher: Paul Manning Lead Editor: Frank Pohlmann Technical Reviewers: Peter Membrey and Ann Tan-Pohlmann Editorial Board: Clay Andres, Steve Anglin, Mark Beckner, Ewan Buckingham, Tony Campbell, Gary Cornell, Jonathan Gennick, Michelle Lowman, Matthew Moodie, Jeffrey Pepper, Frank Pohlmann, Ben Renow-Clarke, Dominic Shakeshaft, Matt Wade, Tom Welsh Coordinating Editor: Debra Kelly Copy Editors: James A. Compton, Heather Lang, Patrick Meader, and Sharon Terdeman Compositor: Bob Cooper Indexer: BIM Indexing and e-Services Artist: April Milne Cover Designer: Anna Ishchenko Distributed to the book trade worldwide by Springer-Verlag New York, Inc., 233 Spring Street, 6th Floor, New York, NY 10013. Phone 1-800-SPRINGER, fax 201-348-4505, e-mail orders-ny@springer-sbm.com, or visit http://www.springeronline.com. For information on translations, please e-mail info@apress.com, or visit http://www.apress.com. Apress and friends of ED books may be purchased in bulk for academic, corporate, or promotional use. eBook versions and licenses are also available for most titles. For more information, reference our Special Bulk Sales—eBook Licensing web page at http://www.apress.com/info/bulksales. The information in this book is distributed on an “as is” basis, without warranty. Although every precaution has been taken in the preparation of this work, neither the author(s) nor Apress shall have any liability to any person or entity with respect to any loss or damage caused or alleged to be caused directly or indirectly by the information contained in this work. The source code for this book is available to readers at http://www.apress.com. www.it-ebooks.info I dedicate this book to all current and future users of Linux. —Ryan Baclit To Anna. May all your dreams come true. —Chivas Sicam For my granddad, Bill “Pappy” Membrey. Without his unwavering support and guidance (not to mention patience), I would not be where I am today. —Peter Membrey To my fiancée, Jenna. —John Newbigin www.it-ebooks.info iv Contents at a Glance ■About the Authors xvii ■About the Technical Reviewer xx ■Acknowledgments xxi ■Introduction xxii ■Chapter 1: Installation 1 ■Chapter 2: BASH 31 ■Chapter 3: Client/Host Configuration 55 ■Chapter 4: Data Storage Management 71 ■Chapter 5: User Management 87 ■Chapter 6: X Window System 105 ■Chapter 7: Package Management 133 ■Chapter 8: Basic Linux Security 153 ■Chapter 10: Network Security 203 ■Chapter 11: Network Services 227 ■Chapter 12: Open Source Databases 261 ■Chapter 13: Linux Web Services 289 ■Chapter 14: File Sharing Services 313 ■Chapter 15: Linux Mail Servers 335 ■Chapter 16: Directory Services 373 ■Chapter 17: The Linux Kernel 415 ■Chapter 18: Linux Virtualization 435 ■Chapter 19: Linux Troubleshooting 457 ■Index 471 www.it-ebooks.info ■ CONTENTS v Contents ■About the Authors xvii ■About the Technical Reviewer xx ■Acknowledgments xxi ■Introduction xxii ■Chapter 1: Installation 1 Preinstallation Steps 1 Installation 3 Troubleshooting 29 Summary 30 ■Chapter 2: BASH 31 Working with the Command-Line Interface 31 Identifying the Working User 32 The Linux Filesystem 33 Directory Management 35 Listing the Contents of a Directory 36 Traversing Directories 39 Absolute and Relative Paths 39 Creating Directories 40 Renaming and Moving Files 40 Deleting Directories and Files 41 Creating and Viewing Text Files 42 Viewing the Contents of a File 44 Text Processing 45 Standard I/O Devices 46 Redirection 47 Piping 47 Getting Help 48 Environment Variables 51 Creating and Running Your Own Script 52 Summary 54 ■Chapter 3: Client/Host Configuration 55 The Boot Process 55 The Boot Loader 55 www.it-ebooks.info ■ CONTENTS vi Kernel, Init, and Runlevels 60 Services 62 Keyboard Settings 63 Language Settings 64 Date and Time Settings 65 Network Settings 67 Graphics Settings 68 Printer Settings 69 Summary 70 ■Chapter 4: Data Storage Management 71 Provisioning a New Hard Drive 71 Partitioning a Disk Using RAID 77 Understanding RAID Types and Levels 78 RAID 0 78 RAID 1 78 RAID 5 79 Checking on RAID 81 Partitioning with LVM 81 Understanding How LVM Works 82 Volume Groups 83 Physical Volumes 83 Logical Volumes 84 Making Sure Your Volumes Work 85 Finding More Information on LVM 85 Summary 85 ■Chapter 5: User Management 87 Managing Users and Groups with the Graphical Interface 87 Adding a User 87 Changing User Properties 89 Deleting a User 91 Adding a Group 91 Changing Group Properties 92 Deleting a Group 93 User Management on the Command Line 93 Adding a User 94 Changing User Properties 94 Deleting a User 95 Adding a Group 96 Changing Group Properties 96 Deleting a Group 96 Implementing Disk Quotas 98 Enabling User and Group Quotas on a Filesystem 99 Setting Up the Quota Files 99 www.it-ebooks.info ■ CONTENTS vii Setting Up Quotas 100 Setting Grace Periods 101 Managing Quotas for Groups 101 Enabling Quotas 101 Reporting on Quotas 101 Setting Resource Limits 102 Summary 103 ■Chapter 6: X Window System 105 X.Org 106 xorg.conf 106 The Keyboard Section 107 The Device Section 108 The Screen Section 108 The ServerLayout Section 110 Making a New xorg.conf File 111 The GNOME Desktop 111 Top Panel 112 Applications 113 Places 115 System 117 Customizing Menus 118 Launchers 120 Separator, Update, Clock, and Sound Applet 121 Bottom Panel 121 XDMCP Remote Connections 122 GDM Configuration 123 Reloading Options with gdmflexiserver 125 Using XDMCP with GDM 125 Requesting an X Session with XDMCP 126 XDMCP with X Query 126 XDMCP with Xnest 128 X with SSH 130 Summary 131 ■Chapter 7: Package Management 133 RPM 133 The RPM Filename Convention 134 The rpm Command 135 Installing a Package 135 Signed Packages 136 Importing Keys 136 Verifying Packages 137 Adding More Output 137 Package Dependencies 138 www.it-ebooks.info ■ CONTENTS viii Upgrading a Package 139 Removing a Package 140 Querying a Package 141 Information and File Contents of a Package 141 Source RPMs 142 The Spec File 143 The rpmbuild Command 144 Building a Binary Package from a Source Package 144 YUM 145 Installing Packages with YUM 146 Removing Packages with YUM 146 Updating Packages with YUM 147 Searching Packages with YUM 148 Adding Sources for YUM 148 Creating Repositories for YUM 150 Summary 151 ■Chapter 8: Basic Linux Security 153 System Logger 153 Using syslog.conf 154 Selectors 155 Actions 157 Detecting Intruders with the System Logger 158 Automating Tasks with cron 160 Using crontab 161 Using cron.allow and cron.deny 161 Working with the crontab File 161 The crontab Task 161 Browsing Available Tasks 163 Removing Tasks 163 Pluggable Authentication Modules 163 Understanding PAM Rules and Configuration Files 165 servicename 166 Management Groups 167 Control 167 modulepath 168 Testing PAM 168 Testing pam_time.so with crond 169 Finding Other PAM Modules 170 Summary 170 ■Chapter 9: Advanced Security 171 Using Digital Certificates 171 Creating Certificates 172 Deploying Certificates 176 www.it-ebooks.info [...]... Foundations of CentOS Linux: Enterprise Linux on the Cheap was written for beginning to intermediate level administrators who want to learn Linux using CentOS This book was designed to be a hands-on type of book to enable you to grasp Linux concepts fast Starting with Chapter 1, you will be given background and instructions on how to install CentOS in your computers properly Then you will install CentOS. .. or CentOS, is an enterprise Linux distribution It was developed by the CentOS Project community using the source code of the commercial Linux distribution from Redhat, the Redhat Enterprise Linux (RHEL) They created CentOS to have a free alternative to RHEL and to have a Linux distribution that's as stable as its commercial counterpart and can keep up with the requirements of the enterprise Using CentOS. .. you won’t be able to see the performance and reliability of CentOS if it is running on virtual machines instead of running standalone So you’ve decided to learn CentOS, the cheapest enterprise Linux operating system available When we say cheap, we mean cheap! You can actually download CentOS for free from this link: http://isoredirect .centos. org /centos/ 5/isos/i386/ We recommend, though, that you obtain... better CentOS after each release CentOS has an interactive community, and you can ask them for assistance (go to http:/ /centos. org) if you need it You can send email to community members to share ideas or ask for solutions on the problems that you may have encountered while using CentOS For business users that plan to use CentOS on their organization, they can avail of commercial support for CentOS. .. and software analysis and design with UML When not playing with Linux, he studies manga illustration, reads manga, and collects anime toys ■Chivas Sicam works as an entrepreneur and IT consultant Chivas takes pride in being part of the DOST-ASTI (Department of Science and Technology Advanced Science and Technology Institute) Bayanihan Linux project His team has advocated the use of open source software... your repairs After you finish this book, you will have a better grasp of the basics of Linux in general and CentOS in particular that will be essential when you learn other advanced Linux administration techniques in your career You can get an even more advanced Linux book, and you will find that it is much easier to understand because of what you have learned in this book If you are an aspiring Redhat... and software updates and quality assurance measures to maintain the stability of the distribution The packages they build for CentOS are placed on their distributed mirror network to allow users to download and install software on their system manually if needed Because of the core developers and its community, CentOS is able to have a constant release upgrade schedule to allow users to use new software... need blank CDs or a DVD and a CD/DVD burner and software The instructions for burning a CD/DVD of CentOS are available at http://www .centos. org/docs/5/html/CD_burning_howto.html This link provides instructions on burning your CentOS images once you have downloaded them in both Windows and Linux Preinstallation Steps At this point, you will be installing CentOS as a server on one computer and as a workstation... foundation not only for both CentOS and RHEL but also for the core Linux concepts xxii www.it-ebooks.info ■ INTRODUCTION Here is a brief summary of what each chapter covers on the book: Chapter 1 will give you a walkthrough on how to install CentOS into your computers You will be given advice on how to prepare for your first Linux installations such as where to get an install CentOS DVD and having a checklist... separate instances of CentOS systems within your current CentOS system Chapter 19 will teach you about the basics of Linux troubleshooting to prepare you for situations when your system cannot boot as expected You will learn how to use the rescue environment to enter your system to know why it cannot load, and fix it You will know how to find the correct partitions and directories of your unbootable . page count   CYAN   MAGENTA   YELLOW   BLACK Foundations of CentOS Linux ThE ExpErT’s VOiCE ®  iN LiNux Foundations of CentOS Linux Enterprise Linux On the Cheap Ryan Baclit, Chivas Sicam,. Administration The Definitive Guide to CentOS Pro Ubuntu Server Beginning the Linux Command Line Beginning Ubuntu Linux, 4th edition Beginning SUSE Linux Foundations of CentOS Linux Beginning Ubuntu LTS. last page for details on $10 eBook version Foundations of CentOS Linux: Enterprise Linux On the Cheap Dear Reader, I’ve been using Linux for years for software development, for personal enter- tainment,