Essential System Administration

1178 Pages·2001·13.88 MB·English

Essential System
Administration

THIRD EDITION
Essential System
Administration
Æleen Frisch
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Essential System Administration, Third Edition
by Æleen Frisch
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August 2002: Third Edition.
September 1995: Second Edition.
October 1991: First Edition.
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Library of Congress Cataloging-in-Publication Data
Frisch, AEleen
Essential System Administration/by AEleen Frisch.--3rd ed.
p. cm.
Includes index.
ISBN 0-596-00343-9
ISBN13 978-0-596-00343-2
1. UNIX (Computer file) 2. Operating systems (Computers) I. Title.
QA76.76.063 F75 2002
005.4'32--dc21 2002023321
[M] [05/07]
For Frank Willison
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like it either. Everyone should get off their high
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We all have pressures on us, and nobody’s
pressure is more important than anyone else’s.”
***
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have Volume 3 (Cats–Dorc) of the
Encyclopedia Britannica.”

Table of Contents
Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi
1. Introduction to System Administration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Thinking About System Administration 3
Becoming Superuser 6
Communicating with Users 12
About Menus and GUIs 14
Where Does the Time Go? 31
2. The Unix Way . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Files 33
Processes 53
Devices 61
3. Essential Administrative Tools and Techniques . . . . . . . . . . . . . . . . . . . . . . . . 74
Getting the Most from Common Commands 74
Essential Administrative Techniques 90
4. Startup and Shutdown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
About the Unix Boot Process 127
Initialization Files and Boot Scripts 151
Shutting Down a Unix System 169
Troubleshooting: Handling Crashes and Boot Failures 173
5. TCP/IP Networking. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 180
Understanding TCP/IP Networking 180
Adding a New Network Host 202
Network Testing and Troubleshooting 219
vii
6. Managing Users and Groups . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 222
Unix Users and Groups 222
Managing User Accounts 237
Administrative Tools for Managing User Accounts 256
Administering User Passwords 277
User Authentication with PAM 302
LDAP: Using a Directory Service
for User Authentication 313
7. Security . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 330
Prelude: What’s Wrong with This Picture? 331
Thinking About Security 332
User Authentication Revisited 339
Protecting Files and the Filesystem 348
Role-Based Access Control 366
Network Security 373
Hardening Unix Systems 387
Detecting Problems 391
8. Managing Network Services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 414
Managing DNS Servers 414
Routing Daemons 452
Configuring a DHCP Server 457
Time Synchronization with NTP 469
Managing Network Daemons under AIX 475
Monitoring the Network 475
9. Electronic Mail . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 521
About Electronic Mail 521
Configuring User Mail Programs 532
Configuring Access Agents 537
Configuring the Transport Agent 542
Retrieving Mail Messages 596
Mail Filtering with procmail 599
A Few Final Tools 614
10. Filesystems and Disks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 616
Filesystem Types 617
Managing Filesystems 621
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