Linux Administration : A Beginner's Guide

by Shah, Steve

• ISBN13: 9780072262599
• ISBN10: 0072262591
• Edition: 4th
• Format: Paperback
• Copyright: 2005-10-25
• Publisher: McGraw-Hill Osborne Media

Summary

With coverage of the most recent Linux kernel and multiple Linux platforms including Red Hat Linux Fedora 4, SuSe Linux, Red Hat Enterprise Linux, and others, this updated instructional system is designed to show even the most novice user the keys to successful administration. Readers will learn to install and configure Linux, manage files and software, grant user rights, implement security at the kernel level, and more.

Author Biography

Steve Shah (San Jose, CA) is Director of Product Management at NetScaler where he is responsible for the security and Layer 4-7 switching capabilities of the company's award-winning application delivery systems. Prior to NetScaler, Steve played a similar role at Array Networks as Director of Product Management, where he did everything from kernel level TCP/IP hacking to product marketing. Before Array Networks, he was also a member of Alteon Web Systems team where he lead the development effort of their SSL accelerator product.

Steve is also the author of Linux Administration: A Beginners Guide which is currently in its 3rd edition, and a contributor to several editions of Unix Unleashed, RedHat Linux Unleashed, Using Linux, and Content Delivery Networks. He holds a BS in Computer Science with a minor in Creative Writing, and a MS in Computer Science from UC Riverside. Steve has been programming since 1986, performing systems administration since 1992, and has been concerned about security matters ever since seeing his password appear in a packet trace.

Wale Soyinka (Union City, CA) is a Systems/Network Engineering consultant with several years experience in the field. He has written an extensive library of Linux administration training materials used as part of the curriculum in some Community Colleges in the Bay Area. He is also the author of a projects lab manual "Microsoft Windows 2000 Managing Network Environments" which is part of the Microsoft certification series published by Prentice Hall. His recent work includes participating on the East Bay Community College ITIEP (Information Technology Industry Education Partnership) task force to develop standardized UNIX and Linux curriculum. He also currently participates in several Open Source discussions and projects.

Table of Contents

Acknowledgments	xix
Introduction	xxi
Part I Installing Linux as a Server
Technical Summary of Linux Distributions and Windows 2003	3	(12)
Learning about the Linux Operating System	4	(1)
What Are Free Software and GNU All About?	5	(3)
What Is the GNU Public License?	6	(1)
The Advantages of Free Software	7	(1)
Understanding the Differences Between Windows and Linux	8	(5)
Single Users vs. Multiple Users vs. Network Users	8	(1)
The Monolithic Kernel and the Micro-Kernel	9	(1)
Separation of the GUI and the Kernel	9	(1)
The Network Neighborhood	10	(1)
The Registry vs. Text Files	11	(1)
Domains and Active Directory	12	(1)
Other References	13	(2)
Installing Linux in a Server Configuration	15	(30)
Hardware and Environmental Considerations	16	(1)
Server Design	16	(2)
Uptime	18	(1)
Dual-Booting Issues	18	(1)
Methods of Installation	19	(1)
Installing Fedora Core Linux	20	(24)
Project Prerequisites	20	(1)
Carrying Out the Installation	21	(19)
Initial System Configuration	40	(4)
Summary	44	(1)
Installing Software	45	(26)
The RED HAT Package Manager	46	(14)
Querying with RPM (Getting to Know One Another)	49	(3)
Installing with RPM (Moving in Together)	52	(3)
Uninstalling with RPM (Ending the Relationship)	55	(1)
Other Things You Can Do with RPM	56	(1)
GUI RPM Package Managers	57	(3)
Compile and Install GNU Software	60	(6)
Getting and Unpacking the Package	61	(1)
Looking for Documentation (Getting to Know Each Other---Again)	62	(1)
Configuring the Package	63	(1)
Compiling the Package	64	(1)
Installing the Package	65	(1)
Testing the Software	65	(1)
Cleanup	66	(1)
Common Problems in Building from Source	66	(1)
Problems with Libraries	66	(1)
When There Is No configure Script	67	(1)
Broken Source Code	67	(1)
Summary	67	(4)
Part II Single-Host Administration
Managing Users	71	(28)
What Exactly Constitutes a User?	72	(7)
Where User Information Is Kept	72	(1)
The /etc/passwd file	73	(4)
The /etc/shadow File	77	(1)
The /etc/group File	78	(1)
User Management Tools	79	(6)
Command-Line User Management	79	(4)
GUI User Managers	83	(2)
Users and Access Permissions	85	(1)
Understanding SetUID and SetGID Programs	86	(1)
Pluggable Authentication Modules (PAM)	86	(7)
How PAM Works	87	(1)
PAM's Files and Their Locations	87	(1)
Configuring PAM	88	(5)
Debugging PAM	93	(1)
A Grand Tour	93	(4)
Creating Users with useradd	93	(2)
Creating Groups with groupadd	95	(1)
Modifying User Attributes with usermod	95	(1)
Modifying Group Attributes with groupmod	96	(1)
Deleting Groups and Users with groupdel and userdel	96	(1)
Summary	97	(2)
The Command Line	99	(38)
An Introduction to BASH	100	(5)
Job Control	101	(1)
Environment Variables	102	(3)
Command-Line Shortcuts	105	(2)
Filename Expansion	105	(2)
Documentation Tools	107	(2)
The man Command	107	(2)
The texinfo System	109	(1)
Understanding File Listings, Ownerships, and Permissions	109	(7)
Listing Files: Is	109	(1)
File and Directory Types	110	(1)
Block Devices	111	(1)
Character Devices	112	(1)
Named Pipes	112	(1)
Change Ownership: chown	112	(1)
Change Group: chgrp	113	(1)
Change Mode: chmod	113	(3)
File Management and Manipulation	116	(9)
Copy Files: cp	116	(1)
Move Files: mv	116	(1)
Link Files: In	117	(1)
Find a File: find	117	(1)
File Compression: gzip	118	(1)
bzip2	118	(1)
Create a Directory: mkdir	119	(1)
Remove a Directory: rmdir	119	(1)
Show Present Working Directory: pwd	119	(1)
Tape Archive: tar	119	(3)
Concatenate Files: cat	122	(1)
Display a File One Screen at a Time: more	122	(1)
Disk Utilization: du	122	(1)
Show the Directory Location of a File: which	123	(1)
Locate a Command: whereis	123	(1)
Disk Free: df	124	(1)
Synchronize Disks: sync	124	(1)
Moving a User and Its Home Directory	125	(7)
List Processes: ps	127	(2)
Show an Interactive List of Processes: top	129	(1)
Send a Signal to a Process: kill	130	(2)
Miscellaneous Tools	132	(2)
Show System Name: uname	132	(1)
Who Is Logged In: who	133	(1)
A Variation on who: w	133	(1)
Switch User: su	133	(1)
Editors	134	(1)
vi	134	(1)
emacs	134	(1)
joe	135	(1)
pico	135	(1)
Standards	135	(1)
Summary	136	(1)
Booting and Shutting Down	137	(24)
Boot Loaders	138	(11)
GRUB	138	(10)
LILO	148	(1)
Bootstrapping	148	(1)
The init Process	149	(1)
rc Scripts	150	(5)
Writing Your Own rc Script	151	(4)
Enabling and Disabling Services	155	(3)
Disabling a Service	157	(1)
Odds and Ends of Booting and Shutting Down	158	(2)
fsck!	158	(1)
Booting into Single-User (``Recovery'') Mode	159	(1)
Summary	160	(1)
File Systems	161	(26)
The Makeup of File Systems	162	(3)
i-Nodes	162	(1)
Superblocks	163	(1)
ext3 and ReiserFS	164	(1)
Which File System to Use?	165	(1)
Managing File Systems	165	(8)
Mounting and Unmounting Local Disks	165	(6)
Using fsck	171	(2)
Adding a New Disk	173	(1)
Overview of Partitions	173	(1)
Disk and Partition Naming Conventions	174	(1)
Volume Management	174	(10)
Creating Partitions and Logical Volumes	175	(9)
Creating File Systems	184	(2)
Summary	186	(1)
Core System Services	187	(22)
The init Service	188	(3)
The /etc/inittab File	188	(3)
The telinit Command	191	(1)
xinetd and inetd	191	(8)
The /etc/xinetd.conf File	193	(6)
The Syslogd Daemon	199	(5)
Invoking syslogd	199	(1)
The /etc/syslog.conf File	199	(5)
CRON	204	(3)
The crontab File	205	(1)
Editing the crontab File	206	(1)
Summary	207	(2)
Compiling the Linux Kernel	209	(18)
What Exactly Is a Kernel?	210	(1)
Finding the Kernel Source Code	211	(2)
Getting the Correct Kernel Version	212	(1)
Unpacking the Kernel Source Code	213	(1)
Building the Kernel	213	(11)
Preparing to Configure the Kernel	215	(1)
Kernel Configuration	216	(3)
Compiling the Kernel	219	(1)
Installing the Kernel	220	(2)
Booting the Kernel	222	(1)
The Author Lied---It Didn't Work!	223	(1)
Patching the Kernel	224	(2)
Downloading and Applying Patches	224	(2)
Summary	226	(1)
Knobs and Dials: The proc File System	227	(14)
What's Inside the /proc Directory?	228	(1)
Tweaking Files Inside of /proc	229	(1)
Some Useful /proc Entries	229	(3)
Enumerated /proc Entries	231	(1)
Common Reports and Settings Done with proc	232	(3)
SYN Flood Protection	233	(1)
Issues on High-Volume Servers	234	(1)
Debugging Hardware Conflicts	235	(1)
SysFS	235	(2)
Summary	237	(4)
Part III Security and Networking
TCP/IP for System Administrators	241	(44)
The Layers	242	(7)
Packets	242	(3)
TCP/IP and the OSI Model	245	(4)
Headers	249	(9)
Ethernet	249	(2)
IP	251	(3)
TCP	254	(3)
UDP	257	(1)
A Complete TCP Connection	258	(3)
Opening a Connection	258	(1)
Transferring Data	259	(1)
Closing the Connection	260	(1)
How ARP Works	261	(2)
The ARP Header: ARP Works with Other Protocols, Too!	262	(1)
Bringing IP Networks Together	263	(11)
Hosts and Networks	263	(2)
Netmasks	265	(1)
Static Routing	266	(2)
Dynamic Routing with RIP	268	(6)
Digging into tcpdump	274	(8)
A Few General Notes	274	(2)
Using tcpdump to Watch a Traceroute	276	(1)
Why Is DNS Slow?	277	(2)
Graphing Odds and Ends	279	(3)
Summary	282	(3)
Network Configuration	285	(16)
Modules and Network Interfaces	286	(1)
Using ifconfig to Configure Set IP Addresses	287	(5)
Simple Usage	288	(1)
Setting Up NICs at Boot Time	289	(2)
Additional Parameters	291	(1)
Using Routes	292	(3)
Simple Usage	292	(1)
Displaying Routes	293	(2)
A Simple Linux Router	295	(3)
Routing with Static Routes	295	(3)
How Linux Chooses an IP Address	298	(1)
Summary	299	(2)
Configuring the Linux Firewall	301	(26)
How Netfilter Works	302	(7)
A NAT Primer	303	(3)
NAT-Friendly Protocols	306	(1)
Chains	306	(3)
Installing Netfilter	309	(4)
Enabling Netfilter in the Kernel	310	(2)
Compiling IPTables	312	(1)
Configuring Netfilter	313	(9)
Saving Your Netfilter Configuration	314	(1)
The iptables Command	315	(7)
Cookbook Solutions	322	(3)
Rusty's Three-Line NAT	322	(1)
Configuring a Simple Firewall	323	(2)
Summary	325	(2)
Local Security	327	(16)
Common Sources of Risk	329	(7)
SetUID Programs	329	(2)
Unnecessary Processes	331	(2)
Programs That Run as Root	333	(1)
Access Granted to Users	333	(3)
Mitigating Risk	336	(3)
Using Chroot	336	(3)
SELinux	339	(1)
Monitoring Your System	339	(2)
Logging	339	(1)
Using ps and netstat	340	(1)
Using df	340	(1)
Mailing Lists	340	(1)
Summary	341	(2)
Network Security	343	(14)
TCP/IP and Network Security	344	(1)
The Importance of Port Numbers	344	(1)
Tracking Services	345	(5)
Using the netstat Command	345	(1)
Security Implications of netstat's Output	346	(2)
Shutting Down Services	348	(2)
Monitoring Your System	350	(1)
Making the Best Use of syslog	350	(1)
Monitoring Bandwidth with MRTG	351	(1)
Handling Attacks	351	(1)
Network Security Tools	352	(2)
Summary	354	(3)
Part IV Internet Services
DNS	357	(38)
The Hosts File	358	(1)
Understanding How DNS Works	359	(6)
Domains and Hosts Naming Conventions	359	(2)
Subdomains	361	(2)
The in-addr.arpa Domain	363	(1)
Types of Servers	363	(2)
Installing a DNS Server	365	(5)
Understanding the BIND Configuration File	367	(1)
The Specifics	367	(3)
Configuring a DNS Server	370	(8)
Defining a Primary Zone in the named.conf File	371	(1)
Defining a Secondary Zone in the named.conf File	372	(1)
Defining a Caching Zone in the named.conf File	373	(1)
DNS Records Types	373	(5)
Setting Up BIND Database Files	378	(5)
Breaking Out the Individual Steps	379	(4)
The DNS Toolbox	383	(6)
host	383	(1)
dig	384	(2)
nslookup	386	(1)
whois	387	(1)
nsupdate	388	(1)
The rndc Tool	388	(1)
Configuring DNS Clients	389	(4)
The Resolver	390	(2)
Configuring the Client	392	(1)
Summary	393	(2)
FTP	395	(18)
The Mechanics of FTP	396	(15)
Client/Server Interactions	396	(2)
Obtaining and Installing vsftpd	398	(1)
Configuring vsftpd	399	(8)
Customizing the FTP Server	407	(4)
Summary	411	(2)
Setting Up Your Web Server Using Apache	413	(16)
Understanding the HTTP Protocol	414	(3)
Headers	414	(1)
Ports	415	(1)
Process Ownership and Security	416	(1)
Installing the Apache HTTP Server	417	(2)
Apache Modules	418	(1)
Starting Up and Shutting Down Apache	419	(2)
Starting Apache at Boot Time	420	(1)
Testing Your Installation	421	(1)
Configuring Apache	421	(6)
Creating a Simple Root-Level Page	421	(1)
Apache Configuration Files	422	(1)
Common Configuration Options	422	(5)
Troubleshooting Apache	427	(1)
Summary	428	(1)
SMTP	429	(12)
Understanding SMTP	430	(3)
Rudimentary SMTP Details	430	(2)
Security Implications	432	(1)
Installing the Postfix Server	433	(3)
Installing Postfix via RPM	433	(1)
Installing Postfix from Source Code	434	(2)
Configuring the Postfix Server	436	(2)
The main.cf File	436	(2)
Checking Your Configuration	438	(1)
Running the Server	438	(2)
Checking the Mail Queue	439	(1)
Flushing the Mail Queue	439	(1)
The newaliases Command	439	(1)
Making Sure Everything Works	439	(1)
Summary	440	(1)
POP and IMAP	441	(12)
The Mechanics of POP and IMAP	444	(2)
Checking POP	444	(1)
Checking IMAP	445	(1)
Installing the UW-IMAP and POP3 Server	446	(3)
Other Issues in Mail Services	449	(2)
SSL Security	449	(1)
Availability	450	(1)
Log Files	451	(1)
Summary	451	(2)
The Secure Shell (SSH)	453	(20)
Understanding Public Key Cryptography	454	(3)
Key Characteristics	456	(1)
Cryptography References	457	(1)
Understanding SSH Versions and Distributions	457	(2)
OpenSSH and OpenBSD	458	(1)
Alternative Vendors for SSH Clients	458	(1)
The Weakest Link	459	(1)
Downloading, Compiling, and Installing SSH from Source	459	(3)
Installing OpenSSH via RPM	462	(2)
Server Startup and Shutdown	462	(1)
SSHD Configuration File	463	(1)
Using Openssh	464	(1)
The ssh Client	464	(1)
Creating a Secure Tunnel	464	(6)
Secure Copy (scp)	468	(1)
Secure FTP (sftp)	468	(1)
Files Used by SSH	469	(1)
Summary	470	(3)
Part V Intranet Services
Network File System (NFS)	473	(20)
The Mechanics of NFS	474	(6)
Versions of NFS	475	(1)
Security Considerations for NFS	476	(1)
Mount and Access a Partition	476	(1)
Enabling NFS	477	(1)
The Components of NFS	478	(1)
Kernel Support for NFS	479	(1)
Configuring an NFS Server	480	(4)
The /etc/exports Configuration File	480	(2)
Telling the NFS Server Process about /etc/exports	482	(1)
The showmount Command	483	(1)
Troubleshooting Server-Side NFS Issues	484	(1)
Configuring NFS Clients	484	(5)
The mount Command	485	(1)
Soft vs. Hard Mounts	485	(1)
Cross-Mounting Disks	485	(3)
The Importance of the intr Option	488	(1)
Performance Tuning	488	(1)
Troubleshooting Client-Side NFS Issues	489	(1)
Stale File Handles	489	(1)
Permission Denied	489	(1)
Client and Server NFS Configuration	490	(1)
Common Uses for NFS	491	(1)
Summary	492	(1)
Network Information Service (NIS)	493	(24)
Inside NIS	494	(2)
The NIS Servers	495	(1)
Domains	496	(1)
Configuring the Master NIS Server	496	(8)
Establishing the Domain Name	497	(1)
Starting NIS	498	(1)
Editing the Makefile	498	(4)
Using ypinit	502	(2)
Configuring an NIS Client	504	(6)
Editing the /etc/yp.conf File	504	(1)
Enabling and starting ypbind	505	(1)
Editing the /etc/nsswitch.conf File	506	(2)
NIS at Work	508	(2)
Testing Your NIS Client Configuration	510	(1)
Configuring a Secondary NIS Server	510	(2)
Setting the Domain Name	510	(1)
Setting Up the NIS Master to Push to Slaves	511	(1)
Running ypinit	511	(1)
NIS Tools	512	(1)
Using NIS in Configuration Files	513	(1)
Implementing NIS in a Real Network	514	(1)
A Small Network	514	(1)
A Segmented Network	514	(1)
Networks Bigger Than Buildings	515	(1)
Summary	515	(2)
Samba	517	(20)
The Mechanics of SMB	518	(5)
Usernames and Passwords	518	(1)
Encrypted Passwords	519	(1)
Samba Daemons	519	(1)
Installing Samba	520	(1)
Compiling and Installing Samba from Source	521	(2)
Samba Administration	523	(1)
Starting and Stopping Samba	523	(1)
Using SWAT	524	(5)
Setting Up SWAT	524	(2)
The SWAT Menus	526	(1)
Creating a Share	527	(2)
Using smbclient	529	(3)
Browsing a Server	530	(1)
Remote File Access	530	(2)
Mounting Remote Samba Shares	532	(1)
Creating Samba Users	532	(2)
Allowing NULL Passwords	533	(1)
Changing Passwords with smbpasswd	533	(1)
Using Samba to Authenticate Against a Windows Server	534	(1)
Troubleshooting Samba	535	(1)
Summary	536	(1)
LDAP	537	(20)
LDAP Basics	538	(3)
LDAP Directory	538	(1)
Client/Server Model	539	(1)
Uses of LDAP	540	(1)
LDAP Terminologies	540	(1)
OpenLDAP	541	(7)
Server-Side Daemons	541	(1)
OpenLDAP Utilities	542	(1)
Installing OpenLDAP	542	(2)
Configuring slapd	544	(3)
Starting and Stopping slapd	547	(1)
Configuring OpenLDAP Clients	548	(7)
Creating Directory Entries	549	(1)
Searching, Querying, and Modifying the Directory	550	(2)
Using OpenLDAP for User Authentication	552	(3)
Summary	555	(2)
Printing	557	(16)
Printing Terminologies	558	(1)
The CUPS System	559	(2)
Running CUPS	559	(1)
Installing CUPS	559	(1)
Configuring CUPS	560	(1)
Adding Printers	561	(6)
Local Printers and Remote Printers	562	(1)
Using the Web Interface	563	(2)
Using the Command-Line Tools to Add a Printer	565	(2)
Routine CUPS Administration	567	(2)
Setting the Default Printer	567	(1)
Enabling and Disabling Printers	567	(1)
Accepting and Rejecting Print Jobs	567	(1)
Managing Printing Privileges	568	(1)
Deleting Printers	568	(1)
Managing printers via the Web Interface	568	(1)
Using Client-Side Printing Tools	569	(2)
lpr	570	(1)
lpq	570	(1)
lprm	571	(1)
Summary	571	(2)
DHCP	573	(12)
The Mechanics of DHCP	574	(1)
The DHCPServer	575	(8)
Installing DHCP Software via RPM	575	(1)
Configuring the DHCP Server	575	(6)
A Sample dhcpd.conf File	581	(1)
General Runtime Behavior	582	(1)
The DHCP Client Daemon	583	(1)
Configuring the DHCP Client	583	(1)
Summary	584	(1)
Backups	585	(14)
Evaluating Your Backup Needs	586	(3)
How Much Data?	586	(1)
What Kind of Media?	587	(1)
Performance Considerations of Tape	588	(1)
How Much Network Throughput?	588	(1)
What Speed of Recovery?	588	(1)
What Kind of Tape Management?	589	(1)
Managing the Tape Device	589	(3)
Using mknod and scsidev to Create the Device Files	590	(1)
Manipulating the Tape Device with mt	591	(1)
Command-Line Tools	592	(5)
dump and restore	592	(5)
tar	597	(1)
Summary	597	(2)
Index	599