Certification Summary

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You can configure a number of network sharing services on your RHEL 3 computer. Apache is the most important Web server on the Internet. Squid allows you to save bandwidth. The very secure FTP daemon allows you to let users transfer files to and from your server efficiently and securely. Mail services enable you to set up e-mail send and receive functions on your network.

Apache was developed from the NCSA Web server. Once the appropriate packages are installed, you have a structure and sample Web pages in the /var/www/html directory, based on the /etc/httpd/conf/httpd.conf configuration file. The httpd.conf file is organized in containers. You can create virtual hosts for multiple Web sites on your computer, even if you have only one IP address.

Squid is a proxy server that allows a network to filter its HTTP and FTP traffic through a cache. Requests are taken from the cache when possible. This reduces the load between the LAN and the Internet, reducing your network costs. When users access cached files, they get better performance from the external network.

FTP has two parts: the client and the server. FTP clients such as ftp and lftp are available from the command line. Red Hat includes one FTP server, the very secure FTP service. You can configure it in detail through the /etc/vsftpd/vsftpd.conf configuration file.

Red Hat includes two mail servers with RHEL 3: sendmail and postfix. Both rely on SMTP to send e-mail over the Internet. The sendmail service includes difficult-to-read configuration files: sendmail.cf and submit.cf, both in the /etc/mail directory. Fortunately, you can configure these files through easier-to-read macro files, sendmail.mc and submit.mc. postfix is somewhat easier to configure directly through its own configuration file, /etc/postfix/main.cf. Red Hat also provides a variety of e-mail clients, including mail, mutt, and the mail clients that come with the various Web browsers that are also available for Linux. These clients either use POP or IMAP protocols to receive e-mail.

Because RHCE is a performance-based exam, it is important to practice all the skills discussed in this chapter. You may need to use these skills on the exam!

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