Red Hat LINUX 7.2 - OFFICIAL LINUX CUSTOMIZATION... User manual

Red Hat Linux 7.2
The Official Red Hat Linux Customization Guide

ISBN: N/A
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© 2001 Red Hat, Inc.
rhl-cg(EN)-7.2-Print-RHI (2001-08-30T14:29-0400)
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Printed in Canada, Ireland, and Japan
ii

This manual is dedicated to Carole Williams, a valuable contributor to the Red Hat documentation
team. Carole, we wish you all the best in your future endeavors. We miss your wisdom, superior
editing skills, ability to write humor into just about any topic, and jokes that made each day a joy to
work with you. Every time we eat a piece of chocolate we will think of you!
iii

Contents
Red Hat Linux 7.2
Introduction................................................................................... xi
Document Conventions.................................................................... xi
MoretoCome.............................................................................. xv
Sign Up for Support........................................................................ xv
Part I Installation-Related Reference....................................... 17
Chapter 1 Kickstart Installations............................................ 19
1.1 What are Kickstart Installations?................................................ 19
1.2 How Do You Perform a Kickstart Installation?................................. 19
1.3 Starting a Kickstart Installation.................................................. 21
1.4 The Kickstart File................................................................. 23
1.5 Kickstart Options ................................................................. 24
Chapter 2 Kickstart Configurator........................................... 47
2.1 Basic Configuration............................................................... 47
2.2 Boot Loader Options ............................................................. 49
2.3 Installation Method ............................................................... 50
2.4 Partition Information.............................................................. 52
2.5 Network Configuration ........................................................... 54
2.6 Authentication..................................................................... 55
2.7 Firewall Configuration............................................................ 56
2.8 X Configuration ................................................................... 56
2.9 Package Selection................................................................ 60
2.10 Pre-Installation Script ............................................................ 61
2.11 Post-Installation Script ........................................................... 62
2.12 Saving the File.................................................................... 64
Chapter 3 Rescue Mode .......................................................... 65
iv

3.1 What is Rescue Mode? .......................................................... 65
Chapter 4 Redundant Array of Independent Disks (RAID) .71
4.1 What is RAID? .................................................................... 71
4.2 Who Should Use RAID? ......................................................... 71
4.3 Hardware RAID versus Software RAID ........................................ 71
4.4 RAID Levels and Linear Support................................................ 72
Chapter 5 Software RAID Configuration ............................... 75
Part II Network-Related References.......................................... 79
Chapter 6 Network Configuration .......................................... 81
6.1 Adding Network Hardware....................................................... 81
6.2 Adding a Device .................................................................. 83
6.3 Managing DNS Settings ......................................................... 85
Chapter 7 Basic Firewall Configuration ................................ 87
7.1 Basic............................................................................... 88
7.2 Local Hosts........................................................................ 89
7.3 DHCP.............................................................................. 89
7.4 Configuring Services............................................................. 90
7.5 Activating the Firewall............................................................ 91
Chapter 8 Controlling Access to Services............................ 93
8.1 Runlevels.......................................................................... 94
8.2 TCP Wrappers.................................................................... 94
8.3 Serviceconf........................................................................ 95
8.4 ntsysv.............................................................................. 97
8.5 chkconfig.......................................................................... 98
8.6 Additional Resources ............................................................ 99
v

Chapter 9 OpenSSH................................................................. 101
9.1 Why Use OpenSSH?............................................................. 101
9.2 Configuring an OpenSSH Server............................................... 101
9.3 Configuring an OpenSSH Client ................................................ 102
9.4 Additional Resources ............................................................ 107
Chapter 10 Network File System (NFS) ................................... 109
10.1 Why Use NFS? ................................................................... 109
10.2 Mounting NFS Filesystems...................................................... 109
10.3 Exporting NFS Filesystems ..................................................... 111
10.4 Additional Resources ............................................................ 112
Chapter 11 Samba...................................................................... 115
11.1 Why Use Samba? ................................................................ 115
11.2 Configuring Samba............................................................... 115
11.3 Connecting to a Samba Share.................................................. 116
11.4 Using Samba with Windows NT 4.0 and Windows 2000..................... 117
11.5 Additional Resources ............................................................ 118
Chapter 12 Dynamic Host Configuration Protocol (DHCP) .. 121
12.1 Why Use DHCP? ................................................................. 121
12.2 Configuring a DHCP Server..................................................... 121
12.3 Configuring a DHCP Client...................................................... 127
12.4 Additional Resources ............................................................ 128
Chapter 13 Kerberos.................................................................. 129
13.1 Configuring a Kerberos 5 Server................................................ 129
13.2 Configuring a Kerberos 5 Client................................................. 131
13.3 Additional Resources ............................................................ 132
Chapter 14 Apache Configuration............................................ 135
14.1 Basic Settings..................................................................... 136
14.2 Default Settings................................................................... 137
vi

14.3 Virtual Hosts Settings ............................................................ 145
14.4 Server Settings ................................................................... 150
14.5 Performance Tuning.............................................................. 152
14.6 Saving Your Settings ............................................................. 154
14.7 Additional Resources ............................................................ 155
Chapter 15 Apache Secure Server Configuration.................. 157
15.1 Introduction........................................................................ 157
15.2 An Overview of Security-Related Packages................................... 157
15.3 An Overview of Certificates and Security...................................... 160
15.4 Using Pre-Existing Keys and Certificates...................................... 161
15.5 Types of Certificates.............................................................. 162
15.6 Generating a Key ................................................................. 163
15.7 Generating a Certificate Request to Send to a CA ........................... 165
15.8 Creating a Self-Signed Certificate .............................................. 167
15.9 Testing Your Certificate .......................................................... 168
15.10 Accessing Your Secure Server.................................................. 169
15.11 Additional Resources ............................................................ 170
Chapter 16 BIND Configuration................................................ 173
16.1 Adding a Forward Master Zone ................................................. 174
16.2 Adding a Reverse Master Zone................................................. 176
16.3 Adding a Slave Zone............................................................. 178
Part III System Configuration ..................................................... 181
Chapter 17 Console Access...................................................... 183
17.1 Disabling Shutdown Via Ctrl-Alt-Del............................................ 183
17.2 Disabling Console Program Access ............................................ 184
17.3 Disabling All Console Access ................................................... 184
17.4 Defining the Console............................................................. 184
17.5 Making Files Accessible From the Console.................................... 185
17.6 Enabling Console Access for Other Applications ............................. 185
vii

17.7 The floppy Group ................................................................. 186
Chapter 18 Time and Date Configuration................................ 187
18.1 Time and Date Properties ....................................................... 187
18.2 Time Zone Configuration ........................................................ 189
Chapter 19 User and Group Configuration............................. 191
19.1 Adding a New User............................................................... 192
19.2 Modifying User Properties....................................................... 193
19.3 Adding a New Group............................................................. 194
19.4 Modifying Group Properties ..................................................... 195
Chapter 20 Gathering System Information ............................. 197
20.1 System Processes................................................................ 197
20.2 Memory Usage ................................................................... 199
20.3 Filesystems ....................................................................... 200
20.4 Hardware.......................................................................... 201
20.5 Sysreport.......................................................................... 202
20.6 Additional Resources ............................................................ 203
Chapter 21 Printer Configuration............................................. 205
21.1 Adding a Local Printer ........................................................... 207
21.2 Adding a Remote UNIX Printer ................................................. 210
21.3 Adding a Samba (SMB) Printer ................................................. 212
21.4 Adding a Novell NetWare (NCP) Printer ....................................... 215
21.5 Adding a JetDirect Printer ....................................................... 216
21.6 Selecting the Print Driver and Finishing........................................ 218
21.7 Printing a Test Page.............................................................. 220
21.8 Modifying Existing Printers ...................................................... 220
21.9 Saving the Configuration File.................................................... 223
21.10 Managing Your Print Jobs ....................................................... 224
21.11 Additional Resources ............................................................ 224
viii

Chapter 22 Automated Tasks.................................................... 227
22.1 Cron................................................................................ 227
22.2 Configuring a Cron Task......................................................... 227
22.3 Anacron............................................................................ 229
22.4 Additional Resources ............................................................ 230
Chapter 23 Ugrading the Kernel............................................... 233
23.1 The 2.4 Kernel .................................................................... 233
23.2 Preparing to Upgrade ............................................................ 234
23.3 Downloading the Upgraded Kernel ............................................. 235
23.4 Performing the Upgrade ......................................................... 235
23.5 Configuring the Boot Loader .................................................... 236
23.6 Additional Resources ............................................................ 239
Chapter 24 Kernel Modules....................................................... 241
24.1 Kernel Module Utilities ........................................................... 241
24.2 Additional Resources ............................................................ 243
Part IV Package Management ..................................................... 245
Chapter 25 Package Management with RPM.......................... 247
25.1 RPM Design Goals............................................................... 247
25.2 UsingRPM........................................................................ 248
25.3 Checking a Package’s Signature ............................................... 254
25.4 Impressing Your Friends with RPM............................................. 256
25.5 Additional Resources ............................................................ 258
Chapter 26 Gnome-RPM............................................................ 261
26.1 Starting Gnome-RPM ............................................................ 262
26.2 The Package Display............................................................. 264
26.3 Installing New Packages......................................................... 265
26.4 Configuration...................................................................... 267
26.5 Package Manipulation............................................................ 273
ix

Chapter 27 Red Hat Network..................................................... 279
Part V Appendixes....................................................................... 281
Appendix A Building a Custom Kernel..................................... 283
A.1 Building a Modularized Kernel .................................................. 283
A.2 Making an initrd Image........................................................... 286
A.3 Configuring the Boot Loader .................................................... 286
A.4 Building a Monolithic Kernel..................................................... 289
Appendix B Getting Started with Gnu Privacy Guard............. 291
B.1 An Introduction to GnuPG ....................................................... 291
B.2 Generating a Keypair............................................................. 292
B.3 Generating a Revocation Certificate............................................ 294
B.4 Exporting your Public Key ....................................................... 295
B.5 Importing a Public Key ........................................................... 298
B.6 What Are Digital Signatures? ................................................... 299
B.7 Additional Resources ............................................................ 299
x

Section 0.1:Document Conventions xi
Introduction
Welcome to the Official Red Hat Linux Customization Guide.
The Official Red Hat Linux Customization Guide contains information on how to customize your Red
Hat Linux system to fit your needs. If you are looking for step-by-step, task-oriented guides for config-
uring and customizing your system, this is the guide for you. This manual discusses many intermediate
topics such as the following:
• Setting up a network interface card (NIC)
• Performing a Kickstart installation
• Configuring Samba shares
• Managing your software with RPM
• Upgrading your kernel
This manual is divided into the following main categories:
• Installation-Related Reference
• Network-Related Reference
• System Configuration
• Package Management
This guide assumes you have a basic understanding of your Red Hat Linux system. If you need ref-
erence material which covers more basic issues, please refer to the Official Red Hat Linux Getting
Started Guide. If you need more advanced documentation, please refer to the Official Red Hat Linux
Reference Guide.
HTML and PDF versions of all the Official Red Hat Linux manuals are available online at
http://www.redhat.com/support/manuals/.
Document Conventions
When you read this manual, you will see that certain words are represented in different fonts, type-
faces, sizes and weights. This highlighting is systematic; different words are represented in the same
style to indicate their inclusion in a specific category. The types of words that are represented this way
include the following:
command

xii Introduction
Linux commands (and other operating system commands, when used) are represented this way.
This style should indicate to you that you can type in the word or phrase on the command line
and press [Enter] to invoke a command. Sometimes a command contains words that would be
displayed in a different style on their own (e.g., filenames). In these cases, they are considered
to be part of the command, so the entire phrase will be displayed as a command. For example:
Use the cat testfile command to view the contents of a file, named testfile, in the
current working directory.
filename
Filenames, directory names, paths and RPM package names are represented this way. This style
should indicate that a particular file or directory exists by that name on your Red Hat Linux
system. Examples:
The .bashrc file in your home directory contains bash shell definitions and aliases for your
own use.
The /etc/fstab file contains information about different system devices and filesystems.
The /usr/share/doc directory contains documentation for various programs.
Install the webalizer RPM if you want to use a Web server log file analysis program.
application
This style should indicate to you that the program named is an end-user application (as opposed
to system software). For example:
Use Netscape Navigator to browse the Web.
[key]
A key on the keyboard is shown in this style. For example:
To use [Tab] completion, type in a character and then press the [Tab] key. Your terminal will
display the list of files in the directory that start with that letter.
[key]-[combination]
A combination of keystrokes is represented in this way. For example:
The [Ctrl]-[Alt]-[Backspace] key combination will restart the X Window System.
text found on a GUI interface
A title, word or phrase found on a GUI interface screen or window will be shown in this style.
When you see text shown in this style, it is being used to identify a particular GUI screen or an
element on a GUI screen (e.g., text associated with a checkbox or field). Examples:
On the GNOME Control Center screen, you can customize your GNOME window manager.

Section 0.1:Document Conventions xiii
SelecttheRequirePasswordcheckbox ifyouwouldlikeyourscreensavertorequireapassword
before stopping.
top level of a menu on a GUI screen or window
When you see a word in this style, it indicates that the word is the top level of a pulldown menu.
If you click on the word on the GUI screen, the rest of the menu should appear. For example:
Under Settings on a GNOME terminal, you will see the following menu items: Preferences,
Reset Terminal,Reset and Clear, and Color selector.
If you need to type in a sequence of commands from a GUI menu, they will be shown like the
following example:
Click on Programs=>Applications=>Emacs to start the Emacs text editor.
button on a GUI screen or window
This style indicates that the text will be found on a clickable button on a GUI screen. For ex-
ample:
Click on the Back button to return to the Web page you last viewed.
computer output
When you see text in this style, it indicates text displayed by the computer on the command line.
You will see responses to commands you typed in, error messages and interactive prompts for
your input during scripts or programs shown this way. For example:
Use the ls to display the contents of a directory:
$ls
Desktop axhome logs paulwesterberg.gif
Mail backupfiles mail reports
The output returned in response to the command (in this case, the contents of the directory) is
shown in this style.
prompt
A prompt, which is a computer’s way of signifying that it is ready for you to input something,
will be shown in this style. Examples:
$
#
[stephen@maturin stephen]$
leopard login:
user input

xiv Introduction
Text that the user has to type, either on the command line, or into a text box on a GUI screen, is
displayed in this style. In the following example, text is displayed in this style:
To boot your system into the text based installation program, you will need to type in the text
command at the boot: prompt.
Another example, with the word root displayed as something the user needs to type in:
If you need to log in as root when you first log into your system, and you are using the graphical
login screen, at the Login prompt, type root. At the Password prompt, type in the root
password.
glossary entry
A word that appears in the glossary will be shown in the body of the document in this style. For
example:
The lpd daemon handles printing requests.
In this case, the style of the word daemon should indicate to you that a definition of the term is
available in the glossary.
Additionally, we use several differentstrategies to drawyour attention to certain piecesof information.
In order of how critical the information is to your system, these items will be marked as a note, a
caution or a warning. For example:
Note
Remember that Linux is case sensitive. In other words, a rose is not a ROSE
is not a rOsE.
CAUTION
Do not do routine tasks as root — use a regular user account unless you need
to use the root account to administer your system.

Section 0.3:Sign Up for Support xv
WARNING
If you choose not to partition manually, a server installation will remove
all existing partitions on all installed hard drives. Do not choose this
installation class unless you are sure you have no data you need to save.
More to Come
The Official Red Hat Linux Customization Guide is part of Red Hat’s growing commitment to provide
useful and timely support to Red Hat Linux users. As new tools and applications are released, this
guide will be expanded to include them.
Send in Your Feedback
If you spot a typo in the Official Red Hat Linux Customization Guide, or if you have thought of a
way to make this manual better, we would love to hear from you! Please submit a report in Bugzilla (
http://www.redhat.com/bugzilla) against the component rhl-cg.
Be sure to mention the manual’s identifier:
rhl-cg(EN)-7.2-Print-RHI (2001-08-30T14:29-0400)
If you mention this manual’s identifier, we will know exactly which version of the guide you have.
If you have a suggestion for improving the documentation, try to be as specific as possible. If you
have found an error, please include the section number and some of the surrounding text so we can
find it easily.
Sign Up for Support
If you have an official edition of Red Hat Linux 7.2, please remember to sign up for the benefits you
are entitled to as a Red Hat customer.
You will be entitled to any or all of the following benefits, depending upon the Official Red Hat Linux
product you purchased:
• Official Red Hat support —Get help with your installation questionsfrom Red Hat, Inc.’s support
team.
• Red Hat Network — Easily update your packages and receivesecurity notices that are customized
for your system. Go to http://rhn.redhat.com for more details.

xvi Introduction
•Under the Brim: The Official Red Hat E-Newsletter — Every month, get the latest news and
product information directly from Red Hat.
To sign up, go to http://www.redhat.com/apps/activate/. You will find your Product ID on a black,
red, and white card in your Official Red Hat Linux box.
To read more about technical support for Official Red Hat Linux, refer to the Getting TechnicalSupport
Appendix in the Official Red Hat Linux Installation Guide.
Good luck, and thank you for choosing Red Hat Linux!
The Red Hat Documentation Team

Part I Installation-Related Reference

Section 1.2:How Do You Perform a Kickstart Installation? 19
1 Kickstart Installations
1.1 What are Kickstart Installations?
Many system administrators would prefer to use an automated installation method to install Red Hat
Linux on their machines. To answer this need, Red Hat created the kickstartinstallation method. Using
kickstart, a system administrator can create a single file containing the answers to all the questions that
would normally be asked during a typical Red Hat Linux installation.
Kickstart files can be kept on single server system, and read by individual computers during the instal-
lation. This installation method can support the use of a single kickstart file to install Red Hat Linux
on multiple machines, making it ideal for network and system administrators.
Kickstart lets you automate most of a Red Hat Linux installation, including:
• Language selection
• Mouse configuration
• Keyboard selection
• Boot loader installation
• Disk partitioning
• Network configuration
• NIS, LDAP, Kerberos, Hesiod, and Samba authentication
• Firewall configuration
• Package selection
• X Window System configuration
1.2 How Do You Perform a Kickstart Installation?
Kickstart installations can be performed using a local CD-ROM, a local hard drive, or via NFS, FTP
or HTTP.
To use kickstart mode, you must first create a kickstart file (ks.cfg), and make it available to the
Red Hat Linux installation program.
1.2.1 Where to Put A Kickstart File
A kickstart file must be placed in one of two locations:

20 Chapter 1:Kickstart Installations
• On a boot disk
• On a network
Normally a kickstart file is copied to the boot disk, or made available on the network. The net-
work-based approach is most commonly used, as most kickstart installations tend to be performed
on networked computers.
Let us take a more in-depth look at where the kickstart file may be placed.
To perform a diskette-based kickstart installation, the kickstart file must be named ks.cfg and must
be locatedin the boot disk’s top-leveldirectory. Note thatthe Red Hat Linux bootdisks are inMS-DOS
format, so it is easy to copy the kickstart file under Linux using the mcopy command:
mcopy ks.cfg a:
Alternatively, you can use Windows to copy the file. You can also mount the MS-DOS boot disk and
cp the file over. Although there’s no technological requirement for it, most diskette-based kickstart
installations install Red Hat Linux from a local CD-ROM.
Network installations using kickstart are quite common, because system administrators can easily au-
tomate the installation on many networked computers quickly and painlessly. In general, the approach
most commonly used is for the administrator to have both a BOOTP/DHCP server and an NFS server
on the local network. The BOOTP/DHCP server is used to give the client system its networking infor-
mation, while the actual files used during the installation are served by the NFS server. Often, these
two servers run on the same physical machine, but they are not required to.
To perform a network-based kickstart installation, you must have a BOOTP/DHCP server on your
network, and it must include configuration information for the machine on which you are attempting
to install Red Hat Linux. The BOOTP/DHCP server will provide the client with its networking infor-
mation as well as the location of the kickstart file.
If a kickstart file is specified by the BOOTP/DHCP server, the client system will attempt an NFS
mount of the file’s path, and will copy the specified file to the client, using it as the kickstart file. The
exact settings required vary depending on the BOOTP/DHCP server you use.
Here’s an example of a line from the dhcpd.conf file for the DHCP server shipped with Red Hat
Linux:
filename "/usr/new-machine/kickstart/" ;
next-server
blarg.redhat.com;
Note that you should replace the value after filename with the name of the kickstart file (or the
directory in which the kickstart file resides) and the value after next-server with the NFS server
name.