Guide to Red Hat Linux

Whether you're a Linux newbie looking for goof-proof installation tips or a Red Hat veteran who wants the scoop on the latest networking, desktop, and server enhancements, this authoritative guide delivers all the information you need to make the most of Red Hat Linux 7.2. From customizing a desktop to troubleshooting a network or setting up a Web server, it's the only reference you'll ever need to become a Red Hat Linux pro.

Inside, you'll find complete coverage of Red Hat Linux:

_ Take advantage of expert tips for fast, painless installation
_ Learn your way around the Linux shell, file system, and X Window system
_ Master Linux administration, from automating system tasks to locking in security
_ Discover how easy it is to set up a LAN and connect to the Internet
_ Find expert help on tracking down and fixing typical problems
_ Get the scoop on configuring servers, from Web and print servers to e-mail and FTP servers

Chapter 1: An Overview Of Red Hat Linux

Linux is a free computer operating system that was created by Linus Torvalds in 1991 and that has grown from contributions from software developers all over the world. Red Hat Linux is a distribution of Linux that packages together the software needed to run Linux and makes it easier to install and run. Features in Red Hat Linux include a simplified installation procedure, Red Hat Package Management (RPM) tools for managing the software, and easy-to-use Gnome and KDE desktop environments. You can get Red Hat Linux from the Internet, from distributions that come with books such as this one, or from a commercially available boxed set of Red Hat Linux software. Linux is based on a culture of free exchange of software. Linux’s roots are based in the UNIX operating system. UNIX provided most of the framework that was used to create Linux. That framework came in the form of the POSIX standard, which defined the interfaces a UNIX system needs to support in order to be a UNIX system.
 

Chapter 2: Installing Red Hat Linux

Installing Linux is not nearly the adventure it once was. Precompiled binary software and preselected packaging and partitions can make most Red Hat Linux installations a simple proposition. This type of installation has made entering the Linux arena more possible for computer users who are not programmers. Besides providing some step-by-step installation procedures, this chapter discussed some of the trickier aspects of Red Hat Linux installation. In particular, ways of partitioning your hard disk, creating installation boot disks, and changing the boot procedure were described. The chapter also discussed how to reconfigure and install a new kernel.
 

Chapter 3: Getting To Know Red Hat Linux

Working from a shell command-line interpreter within Red Hat Linux may not be as simple as using a GUI, but it offers many powerful and flexible features. This chapter describes how to log in to Red Hat Linux and work with shell commands. Features for running commands include recalling commands from a history list, completing commands, and joining commands in various ways. This chapter describes how shell environment variables can be used to store and recall important pieces of information. It also teaches you to modify shell configuration files to tailor the shell to suit your needs. Finally, the chapter describes how to use the Red Hat Linux file system to create files and directories, understand permissions, and work with files (moving, copying, and removing them).
 

Chapter 4: Working With The Desktop

The X Window System provides the basis for most graphical user interfaces available for Red Hat and other Linux systems today. Although X provides the framework for running and sharing applications, the GNOME and KDE desktop environments, along with a window manager, provide the look-and-feel of your desktop. Using various configuration files and commands, you can change nearly every aspect of your graphical environment. Backgrounds can be assigned a single color or can be filled with single or tiled graphic images. Menus can be changed or enhanced. Multiple virtual workspaces can be used and managed. There are also many settings associated with X itself that you can use directly to change the behavior of your desktop.
 

Chapter 5: Accessing And Running Applications

Between applications written directly for Linux and other UNIX systems, those that have been ported to Linux, and those that can run in emulation, there are hundreds of applications available that can be used with Red Hat Linux. There are dozens of locations on the Internet for downloading Linux applications, and many more that can be purchased on CD. To simplify the process of installing and managing your Linux applications, Red Hat developed the Red Hat Package Manager (RPM). Using tools developed for RPM, such as the rpm command, you can easily install, remove, and do a variety of queries on Linux packages that are in RPM format. Of the types of applications that can run in Linux, those created for the X Window System provide the greatest level of compatibility and flexibility when used in Linux. However, using emulation software, it is possible to run applications intended for DOS, Windows 95/98, and Macintosh operating systems.
 

Chapter 6: Publishing With Red Hat Linux

In recent times, modern GUI-based publishing tools have augmented the text-based publishing tools that have always been available with Red Hat Linux (and other UNIX systems). Publishing tools that come with Red Hat Linux include Groff (which implements traditional troff/nroff text processing) and LaTeX (a TeX macro interface that is particularly suited for scientific and mathematical publishing). In recent years, DocBook, an SGML-based data type definition, has become the standard for producing documentation of Linux and other software projects. Along with Red Hat Linux’s growing popularity, more commercial publishing applications have appeared that work with Red Hat Linux. Anyware Office and Star Office are two application suites that provide powerful publishing features in Linux. The popular WordPerfect word processor has also been ported to Linux. Although you do have to pay for Anyware Office and WordPerfect, their prices are reasonable (especially when measured against comparable MS Windows applications). Red Hat Linux does include one free word processor: AbiWord. Though AbiWord isn't up to the level of the best commercial word processors, it does have good, basic features and potential for the future. To create and manage graphics, Red Hat Linux comes with applications like GIMP, xv, and xpaint. Each of these applications enables you to input and output graphics files from a variety of formats. There is also an interface to scanners called Scanner Access Now Easy (SANE). With SANE, a variety of applications can access scanner devices, and the devices can be shared across a network.
 

Chapter 7: Playing Games With Red Hat Linux

While Red Hat Linux has not yet become a dominant gaming platform, there are still plenty of games running on Red Hat Linux that you can spend your time on. Old UNIX games that have made their way to Linux include a variety of text-based and X Window-based games. There are card games, strategy games, and some action games. For games that were intended for certain gaming consoles and arcade machines, the xmame emulator provides an environment within the Linux system in which those games could be played. Hundreds of game ROMs are available on the Internet, although copyright laws restrict what you can legally download and use. On the commercial front, Civilization: Call to Power for Linux, Myth II, and Quake III Arena are available to use on your Red Hat Linux system. Most of these games offer excellent graphics and animation, but they require certain video cards and drivers to work effectively.
 

Chapter 8: Multimedia In Red Hat Linux

Getting your Red Hat Linux system set up for sound and video can take some doing, but once it’s done you can play most audio and video content that is available today. This chapter took you through the steps of setting up and troubleshooting your sound card. When that was done, you learned how to find software to play music through that card. Video players, such as Xanim, were described for playing video clips in Red Hat Linux. The chapter also covered how to get the RealPlayer from Real Networks so you can draw from the large pool of RealMedia content available on the Web. To download images from a digital camera, the gPhoto window was described. If your computer has a CD burner, use descriptions in this chapter to create your own music CDs and CD labels. The chapter described a few plug-ins that you can add to your Netscape browser to play some types of multimedia content as you browse the Web. Finally, it described the current state of DVD and VRML content in Linux.
 

Chapter 9: Tools For Using The Internet And The Web

Most use of the World Wide Web centers on the Web browser. Over your existing Internet connection, the browser lets you indicate Web pages and other content that you want to access using addresses referred to as URLs (Uniform Resource Locators). Mozilla and Netscape are the most popular browsers with Red Hat and other Linux systems, and are accessible from a button on your desktop. E-mail is probably the Internet application that is used most. The e-mail program that comes with Mozilla, called Mozilla Mail, integrates well with the Mozilla browser and provides most everything needed for reading, sending, and managing your mail. There are several traditional UNIX mail programs available with Red Hat Linux as well, including elm, pine, and mail. To read newsgroups, you can use Netscape Messenger. Text-based newsreaders are also available. To pass data around freely between trusted hosts, you can use a set of commands sometimes referred to as “r” commands. The rlogin command lets you log in to other computers over the network. With the rcp command, you can copy one file, many files, or a whole directory structure of files among computers on the network. The rsh command lets you run programs on different computers on a network and direct the output to the local computer or to a remote computer. Commands such as telnet (for remote login) and ftp (for remote file copying) are also available with Red Hat Linux.
 

Chapter 10: Understanding System Administration

Even though you may be using Red Hat Linux as a single-user system, many of the tasks you must do to keep your computer running are defined as administrator tasks. A special user account called the root user is needed to do many of the things necessary to keep Linux working as you would like it to. If you are administering a Linux system that is used by lots of people, the task of administration becomes even larger. You need to be able to add and support users, maintain the file systems, and make sure that system performance serves your users well. To help the administrator, Linux comes with a variety of command-line utilities and graphical windows for configuring and maintaining your system. The linuxconf program contains dozens of configuration and control tasks for everything from network configuration to user setup to run level management tools. The kudzu program can be used to probe and reconfigure Red Hat Linux when you add or remove hardware. Commands such as mkfs and mount let you create and mount file systems, respectively. Tools like top, gtop, and vmstat let you monitor system performance.
 

Chapter 11: Setting Up And Supporting Users

It is not uncommon for a Red Hat Linux system to be used as a single-task server with no actual users. It sits quietly in a server room, serving Web pages or handling domain name service, never crashing, and rarely needing attention. This is not always the case, however. You may have to support users on your Red Hat Linux server, and that can be the most challenging part of your system-administration duties. Red Hat Linux provides a variety of tools that help you with your administrative chores. The useradd, usermod, and userdel commands enable easy command-line manipulation of user account data. Furthermore, creating a support mailbox and building shell scripts to automate repetitive tasks lightens your load even more. Red Hat Linux builds on top of the rich history of UNIX and provides an ideal platform to support the diverse needs of your users.
 

Chapter 12: Automating System Tasks

Shell scripts are an integral part of the Red Hat Linux system for configuring, booting, administering, and customizing Red Hat Linux. They are used to eliminate typing repetitive commands. They are frequently executed from the scheduling facilities within Red Hat Linux, allowing much flexibility in determining when and how often a process should run. And they control the start-up of most daemons and server processes at boot time. The init daemon and its configuration file, /etc/inittab, also factor heavily in the initial start-up of your Red Hat Linux system. They implement the concept of run levels that is carried out by the shell scripts in /etc/rc.d/init.d, and they provide a means by which the machine can be shut down or rebooted in an orderly manner. To have shell scripts configured to run on an ongoing basis, you can use the cron facility. Cron jobs can be added by editing cron files directly or by running commands such as at and batch to enter the commands to be run.
 

Chapter 13: Backing Up And Restoring Files

It may take some work to put a proper backup schedule in place, but the effort is well worth it. Hopefully, you will never experience a major hard drive crash, but if you ever do, the effort of making backups will repay itself many times over. Think of it as an insurance policy. You hope to never use it, but you’re glad you have it when disaster strikes. A variety of low-cost backup hardware is available to use with your Red Hat Linux system. The traditional tape drive is an excellent choice for backing up large amounts of data. If long-term archiving of data is needed, a writable CD drive is a good choice. If minimizing downtime is your main concern, mirroring data to a second hard drive is another smart choice. Whatever backup strategy you choose to use with your Red Hat Linux system, be sure to choose one, and stick with it. You have invested a lot of time creating your data. Invest a little more to keep it safe.
 

Chapter 14: Computer Security Issues

With the rise of the Internet, security has become a critical issue for nearly all computer users. The Red Hat Linux operating system is a powerful tool that can help you get the most out of the Internet, but care must be taken to prevent break-ins by crackers. Proper use of password security in Red Hat Linux is critical, as is proper configuration of the various network services. Understanding system log files so that you can recognize a cracker attack is another important part of defending your system from crackers. In general, knowledge is your most important tool. Learn everything you can about how your Linux system works and where the vulnerabilities are. And remember, good security is not a one-time job; it is an ongoing process that requires constant vigilance. Take advantage of the many great security tools that are available on the Internet. Applications such as Crack, Tiger, and Tripwire can help you keep your system secure. Run them periodically to make sure your system stays secure. Logcheck and PortSentry are software packages produced by Psionic Software, Inc., to help protect your Red Hat Linux system from intrusions from the network. The Logcheck package scans your system logs for messages that may represent break-in attempts. PortSentry takes an active approach to protecting your system by monitoring ports and responding in a variety of ways to those who try to improperly access those ports. Subscribe to the CERT and CIAC mailing lists and install security-related patches as soon as they become available. It is better to spend a few minutes upgrading a system program than to spend many hours rebuilding an entire server.
 

Chapter 15: Setting Up A Local Area Network

Red Hat Linux is at its best when it is connected to a network. Configuring a LAN enables you to share resources with other computers in your home or organization. These resources can include files, printers, CD-ROM drives, and backup media. This chapter describes how to create a LAN with a Red Hat Linux system being used on one of the computers on that LAN. It helps you determine the kind of equipment you need to obtain, and the layout (topology) of the network. On the Red Hat Linux side, you learned about choosing and installing Ethernet cards (also called NICs). You also learned to configure TCP/IP so that you can later employ a variety of TCP/IP tools to use the network. If something isn’t working with your Red Hat Linux interface to the LAN, you can use utilities such as ifconfig to check that your Ethernet interface is configured and running properly. You can also check that Linux found and installed the proper driver for your Ethernet card. After an Ethernet interface is working, you can use the Ethereal window to monitor the packets coming and going across the interface between your computer and the network.
 

Chapter 16: Connecting To The Internet

Connecting to the Internet opens a whole world of possibilities for your Red Hat Linux computer. Using Red Hat Linux as a Web server, mail server, or FTP server depends on Red Hat Linux’s capability to connect to the Internet. Likewise, if your computers are already connected together in a LAN, adding an Internet connection can provide Internet access to everyone on the LAN in one stroke. Descriptions of how Internet domains are organized built on discussions of IP addresses in the previous chapter. Creating dial-up connections to the Internet focused on descriptions of the PPP protocol. Debugging methods were also described. For connecting your LAN to the Internet, several different techniques were discussed. You can set up your Red Hat Linux computer as a router. The Red Hat Linux router either can route packets from computers on your network that have valid IP addresses or can use a special packet-forwarding technique so that computers with private IP addresses can use the Internet. This technique is referred to as IP masquerading. Finally, the last section described how to set up Red Hat Linux as a proxy server. Using Red Hat Linux as a proxy server with the Squid proxy server software, you can save client computers from having to set up DNS and other information themselves. Each client simply has to identify the proxy server to the Web browser to be capable of using that server to gain access to the Internet.
 

Chapter 17: Setting Up A Print Server

Sharing printers is an economical and efficient way to use your organization’s printing resources. A centrally located printer can make it easier to maintain a printer, while still allowing everyone to get his or her printing jobs done. Printer configuration is done with the printconf-gui tool. Printers configured with that tool can be printed using the lpr command. A variety of filters make it possible to print to different kinds of printers, as well as to printers that are connected to computers on the network. Besides being able to set up your computer as a Red Hat Linux print server, you can also have your computer emulate a NetWare or an SMB (Windows 9x) print server. After your network is configured properly and a local printer is installed, sharing that printer over the network as a UNIX, NetWare, or SMB print server is not very complicated.
 

Chapter 18: Setting Up A File Server

By providing centralized file servers, an organization can efficiently share information and applications with people within the organization, with customers, or with anyone around the world. Several different technologies are available in Red Hat Linux to enable you to make your Red Hat Linux computer a file server. The Network File System (NFS) protocol was one of the first file server technologies available. It is particularly well suited for sharing file systems among Red Hat Linux and other UNIX systems, although you can also access NFS file systems from Windows 9x operating systems if those systems are configured to do so. NFS uses standard mount and umount commands to connect file systems into the directory structures of client computers. The Samba software package that comes with Red Hat Linux contains protocols and utilities for sharing files and printers among Windows and OS/2 operating systems. It uses SMB protocols that are included with all Microsoft Windows systems, and therefore provide a convenient method of sharing resources on LANs containing many Windows systems. NetWare was once the dominant network operating system used on LANs. It provided file- and printer-sharing services for networked PCs, although in recent years it has branched out to offer a variety of network services. With the mars_nwe package, you can provide basic NetWare file and print services from your Red Hat Linux computer. With the ncpfs package, you can also use many NetWare client services to query NetWare servers and use NetWare file systems and printers.
 

Chapter 19: Setting Up A Mail Server

Installing a mail server in Red Hat Linux is the easy part; it’s the configuration that takes patience, resolve, and a fair bit of experimentation. Even though it may be considerably faster and easier to utilize the m4 macros, eventually you’ll need to edit the sendmail.cf file. Just hope that it’s not the rewriting rules that need editing. Sooner or later, an alias definition in /etc/aliases will become unmanageable. At this point, mailing list software can provide the flexibility necessary to manage a large distribution list, with the added benefits of archiving, moderation, digesting, and automated administration.
 

Chapter 20: Setting Up An FTP Server

The FTP service is the primary method of offering archives of document and software files to users over the Internet and other TCP/IP networks. The FTP package that is delivered with Red Hat Linux (wu-ftpd) contains a full set of features that enable you to set up and maintain your own FTP server. The FTP server package centers on the ftp daemon process (ftpd, which is run in Red Hat Linux as in.ftpd by the xinetd daemon), which services connection requests to your FTP server. Configuration of features is done in the /etc/ftpaccess file. A wide range of features are available with the ftpaccess file that enable you to control who can access your server, which areas of your file system they can access, and how they can access them (incoming transfers, outgoing transfers, deleting files, renaming files, and so on). To check out your FTP server once it is set up, you can use several different tools. The ftp command is available with Linux and with any other UNIX system. For a more graphical interface, there is the gFTP window. To access your FTP site as most others will access it, you can type the URL of your FTP site in the location box of your browser window. (You can even add FTP user and password information to the location of the FTP site.)
 

Chapter 21: Setting Up A Web Server

Web servers are responsible for storing and delivering the vast amount of content that is available on the World Wide Web to clients all over the world. Although several software packages are available for Red Hat Linux, the most popular (and the one that comes with Red Hat Linux) is the Apache Web server. This chapter describes how to install, configure, and run an Apache server in Red Hat Linux. The httpd daemon process handles requests for Web content (HTTP). Configuration files define what content is made available and how it can be accessed. In particular, the /etc/httpd/conf/httpd.conf file is used to configure the server. The apache package also includes facilities for logging error and transfer messages. You can look for the access_log and error_log files in the /etc/httpd/logs directory. The access_log file contains information on content requests that have been serviced by the server. The error_log file contains listings of error conditions that have occurred and times when service has been denied.
 

Chapter 22: Setting Up A News Server

Setting up a news server can be a complex task. In general, it is a task that should be avoided for most organizations in which only a few users need to access news. (In this case, get access to your ISP’s server if you can.) If, however, you decide that you want to go ahead and build your own news server, the InterNetNews (INN) package comes with Red Hat Linux and is ready to use. Being the administrator of a news server requires that you perform several tasks. The most important file to configure is the inn.conf file (probably located in /etc/news). Many of the basic INN options are set up in that file. In addition to setting up inn.conf, you need to configure which hosts you get your news feed from and which hosts you feed your users' article to. An initial task with INN is to choose and configure a storage method for the articles on your server. The traditional method is to store files in spool directories that are associated with each newsgroup. The timehash storage method enables you to gather news articles based on when they were received (making it easier to enforce policies on how long articles should be kept). The cnfs storage method lets you create buffer files and have them store the articles (rotating out articles when the buffers are full).
 

Chapter 23: Setting Up Boot Servers - DHCP And NIS

DHCP and NIS both provide mechanisms for centrally administering computers on your network. DHCP can provide information that helps client computers get up and running quickly on the network. NIS lets you distribute a wide range of configuration information among Linux and UNIX systems. DHCP is used to provide information about your network to Windows, Linux, Mac, or other client computers on your network. IP addresses can be assigned dynamically, meaning they are distributed from a pool of IP addresses. Or specific addresses can be assigned to clients, based on specific Ethernet hardware addresses. You can configure Red Hat Linux as an NIS client, an NIS master server, or an NIS slave server. An NIS client can take advantage of shared information from an NIS server. The NIS master server builds the databases of information (called maps) and enables access to those maps from the network. Optional NIS slave servers can be used to maintain copies of the NIS maps, enabling NIS service to continue on the network in the event that the NIS master server goes down.
 

Chapter 24: Setting Up A Mysql Database Server

MySQL is a Structured Query Language (SQL) server that runs on Red Hat Linux, as well as other operating systems. Using a start-up script (/etc/init.d/mysqld) and a configuration file (/etc/my.cnf), you can quickly get a MySQL server up and running. With tools such as the mysqladmin and mysql commands, you can administer the MySQL server and create databases and tables that are as simple or complex as you need. During mysql sessions, you can modify the structure of your database tables or add, update, or delete database records. You have a variety of options for querying data and sorting the output. You also have a lot of control over who can access your database tables and what privileges users have to modify, add to, or delete from the databases you control.
 

Chapter 25: Building A Wireless Linux LAN

A wireless LAN can offer an effective way of extending your network to areas that are difficult or expensive to reach with wired connections. Using low-cost wireless LAN cards, you can create peer-to-peer or point-to-point networks. Add Red Hat Linux systems as one or more of your wireless nodes and you can use powerful security, routing, and monitoring tools to further expand and secure your network. You can control your wireless LAN card in Red Hat Linux by passing options to the card's module at start-up time. Once the interface is running, you can use the iwconfig command to change wireless settings, either from the command line or by adding iwconfig options to a configuration file so they are loaded automatically.
 

Chapter 26: Getting Red Hat Linux “Up2date”

The chore of keeping your Red Hat Linux system upgraded with the latest bug fixes, security patches, and enhancements has been simplified greatly with Red Hat’s up2date tool. Using up2date, you can automatically check for updates, download updated packages to your computer, and install them. By registering your system with the Red Hat Network, you can take advantage of services that let you manage your computers and track updates. You can receive free automatic upgrades for the first computer you register; updates for subsequent computers involve a fee. Chris Negus has been working with UNIX systems, the Internet, and (more recently) Linux systems for more than two decades. During that time, Chris worked at AT&T Bell Laboratories, UNIX System Laboratories, and Novell, helping to develop the UNIX operating system. Features from many of the UNIX projects Chris worked on at AT&T have found their way into Red Hat and other Linux systems. During the past few years, Chris has written several books on UNIX and the Internet, including Caldera OpenLinux Bible, Internet Explorer 4 Bible, and Netscape Plug-ins For Dummies for Hungry Minds (formerly IDG Books Worldwide). He also co-wrote several books for Que Corporation, including The Complete Idiot’s Guide to Networking (second and third editions) and Using UNIX (second edition). Chris’s other writings include articles for Internet World, NetWare Connection, and Visual Developer magazines. At home, Chris enjoys spending time with his wife, Sheree, and his boys, Caleb and Seth. His hobbies include soccer, singing, and exercising with Sheree.