Chapter 7: Linux Sharing Services

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Overview

Unix was developed by AT&T in the late 1960s and early 1970s, and was freely distributed among a number of major universities during those years. When AT&T started charging for Unix, a number of developers tried to create clones of this operating system. In one of these efforts, Linux was developed in the early 1990s.

Many of these same universities were also developing the network that evolved into the Internet. With current refinements, this makes Linux perhaps the most Internet-friendly network operating system available. The extensive network services available with Linux are not only the tops in their field, they create one of the most powerful and useful Internet-ready platforms available today at any price.

Currently, Apache is the most popular Web server on the Internet. According to the Netcraft (www.netcraft.com) survey, which tracks the Web server associated with virtually every site on the Internet, Apache is currently used by more Internet Web sites than all the other Web servers combined. Naturally, Apache is included with RHEL 3.

RHEL 3 also includes a number of other services which I discuss in this chapter. These services include the Squid Proxy Server, which caches frequently used pages on a dedicated server. There is the Very Secure FTP (vsFTP) daemon, which provides both basic and secure FTP server services. With vsFTP, you can secure users, directories, subdirectories, and files with various levels of access control.

Inside The Exam

Clients and Servers

On both exams, you'll need to configure a workstation on a network; this includes connecting to all types of network services. On the RHCE exam, you'll configure the corresponding network servers. In this chapter, you'll configure Web (HTTP/ HTTPS), Web proxy, FTP, and various mail services. You need to know how to do the following five things with each of these services:

1. Install the RPM packages or package groups required by the service.

2. Configure the service to start automatically when you reboot Linux.

3. Set up the service for basic operation on your network.

4. Configure security by hosts and users for the service.

5. Use log files, service specific tools, and more to troubleshoot service problems.

   If you're studying for the RHCT exam, read though this chapter. Part of the chapter addresses the network clients such as lftp, Web server, and e-mail that you may configure during your exam.

Other standard services in the Linux/Unix world are e-mail services using the sendmail SMTP server and the POP and IMAP e-mail client services. These are the de facto standards for e-mail on the Internet.

This chapter deals with the basic concepts surrounding the use of these services, and a basic level of configuration. In all cases, the assumption is that your network settings are correct and functioning properly. If you're having problems with your network configuration, read Chapter 3.

As for the RHCE exam, you may have to configure or troubleshoot any of the services discussed in this chapter. So as you read this chapter and look through the configuration files and exercises, be willing to experiment. And practice, practice, practice what you learn.

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