Source: http://webdesign.about.com/cs/apache/a/aainstallapache.htm

Before You Begin

Apache is one of the most popular Web servers on the Web right now, and part of its charm is that it’s free. It also has a lot of features that make it very extensible and useful for many different types of Web sites. It is a server that is used for personal Web pages up to enterprise level sites.

This article will discuss how to install Apache on a Linux system. Before we start you should be at least comfortable working in Linux – changing directories, using tar and gunzip, and compiling with make (I’ll discuss where to get binaries if you don’t want to mess with compiling your own). You should also have access to the root account on the server machine.

Download Apache

I recommend downloading the latest stable release. At the time of this writing, that was Apache 2.0. The best place to get Apache is from the Apache HTTP Server download site. Download the sources appropriate to your system. Binary releases are available as well.

Extract the Files

Once you’ve downloaded the files you need to uncompress them and untarring:
  gunzip -d httpd-2_0_NN.tar.gz
  tar xvf httpd-2_0_NN.tar
This creates a new directory under the current directory with the source files.

Configuring

Once you’ve got the files, you need to tell your machine where to find everything by configuring the source files. The easiest way is to accept all the defaults and just type:
  ./configure

Of course, most people don’t want to accept just the default choices. The most important option is the prefix= option. This specifies the directory where the Apache files will be installed. You can also set specific environment variables and modules. Some of the modules I like to have installed are:

• mod_alias – to map different parts of the URL tree
• mod_include – to parse Server Side Includes
• mod_mime – to associate file extensions with its MIME-type
• mod_rewrite – to rewrite URLs on the fly
• mod_speling (sic) – to help your readers who might misspell URLs
• mod_ssl – to allow for strong cryptography using SSL
• mod_userdir – to allow system users to have their own Web page directories

Please keep in mind that these aren’t all the modules I might install on a given system. Read the details about the modules to determine which ones you need.

Build

As with any source installation, you’ll then need to build the installation:
  make
  make install

Customize

Assuming that there were no problems, you are ready to customize your Apache configuration. This really just amounts to editing the httpd.conf file. This file is located in the PREFIX/conf directory. I generally edit it with vi:
  vi PREFIX/conf/httpd.conf
Note: you’ll need to be root to edit this file.

Follow the instructions in this file to edit your configuration the way you want it. More help is available on the Apache Web site.

Test Your Server

Open a Web browser on the same machine and type http://localhost/ in the address box. You should see a page similar to the one in the partial screen shot above. Specifically, it will say in big letters "Seeing this instead of the website you expected?" This is good news, as it means your server installed correctly.

Start Editing/Uploading Pages

Once your server is up and running you can start posting pages. Have fun building your Web site.

Web Design Path

Professional Web Developers

Suggested Reading

How are You Being Served?
Time to Switch from IIS
Become a Hosting Provider

More Apache Help

How to Install Apache on Windows 
More Apache Resources
Other Web Servers

Source: http://www.redhat.com/docs/manuals/linux/RHL-9-Manual/custom-guide/ch-httpdconfig.html 

In Red Hat Linux 8.0, the Apache HTTP Server was updated to version 2.0, which uses different configuration options. Also starting with Red Hat Linux 8.0, the RPM package was renamed httpd. If you want to migrate an existing configuration file by hand, refer to the migration guide at /usr/share/doc/httpd-<ver>/migration.html or the Red Hat Linux Reference Guide for details.

If you configured the Apache HTTP Server with the HTTP Configuration Tool in previous versions of Red Hat Linux and then performed an upgrade, you can use the application to migrate the configuration file to the new format for version 2.0. Start the HTTP Configuration Tool, make any changes to the configuration, and save it. The configuration file saved will be compatible with version 2.0.

The HTTP Configuration Tool allows you to configure the /etc/httpd/conf/httpd.conf configuration file for the Apache HTTP Server. It does not use the old srm.conf or access.conf configuration files; leave them empty. Through the graphical interface, you can configure directives such as virtual hosts, logging attributes, and maximum number of connections.

Only modules that are shipped with Red Hat Linux can be configured with HTTP Configuration Tool. If additional modules are installed, they can not be configured using this tool.

The httpd and redhat-config-httpd RPM packages need to be installed to use the HTTP Configuration Tool. It also requires the X Window System and root access. To start the application, go to the Main Menu Button => System Settings => Server Settings => HTTP Server or type the command redhat-config-httpd at a shell prompt (for example, in an XTerm or GNOME Terminal).

Caution

Do not edit the /etc/httpd/conf/httpd.conf configuration file by hand if you wish to use this tool. The HTTP Configuration Tool generates this file after you save your changes and exit the program. If you want to add additional modules or configuration options that are not available in HTTP Configuration Tool, you cannot use this tool.

The general steps for configuring the Apache HTTP Server using the HTTP Configuration Tool are as following:

1. Configure the basic settings under the Main tab.

2. Click on the Virtual Hosts tab and configure the default settings.

3. Under the Virtual Hosts tab, configure the Default Virtual Host.

4. If you want to serve more than one URL or virtual host, add the additional virtual hosts.

5. Configure the server settings under the Server tab.

6. Configure the connections settings under the Performance Tuning tab.

7. Copy all necessary files to the DocumentRoot and cgi-bin directories.

8. Exit the application and select to save your settings.

Basic Settings

Use the Main tab to configure the basic server settings.

Figure Basic Settings

Enter a fully qualified domain name that you have the right to use in the Server Name text area. This option corresponds to the ServerName directive in httpd.conf. The ServerName directive sets the hostname of the Web server. It is used when creating redirection URLs. If you do not define a server name, the Web server attempts to resolve it from the IP address of the system. The server name does not have to be the domain name resolved from the IP address of the server. For example, you might want to set the server name to www.example.com when your server’s real DNS name is actually foo.example.com.

Enter the email address of the person who maintains the Web server in the Webmaster email address text area. This option corresponds to the ServerAdmin directive in httpd.conf. If you configure the server’s error pages to contain an email address, this email address will be used so that users can report a problem by sending email to the server’s administrator. The default value is root@localhost.

Use the Available Addresses area to define the ports on which the server will accept incoming requests. This option corresponds to the Listen directive in httpd.conf. By default, Red Hat configures the Apache HTTP Server to listen to port 80 for non-secure Web communications.

Click the Add button to define additional ports on which to accept requests. A window as shown in Figure 19-2 will appear. Either choose the Listen to all addresses option to listen to all IP addresses on the defined port or specify a particular IP address over which the server will accept connections in the Address field. Only specify one IP address per port number. If you want to specify more than one IP address with the same port number, create an entry for each IP address. If at all possible, use an IP address instead of a domain name to prevent a DNS lookup failure. Refer to http://httpd.apache.org/docs-2.0/dns-caveats.html for more information about Issues Regarding DNS and Apache.

Entering an asterisk (*) in the Address field is the same as choosing Listen to all addresses. Clicking the Edit button in the Available Addresses frame shows the same window as the Add button except with the fields populated for the selected entry. To delete an entry, select it and click the Delete button.

Tip

If you set the server to listen to a port under 1024, you must be root to start it. For port 1024 and above, httpd can be started as a regular user.

Default Settings

After defining the Server Name, Webmaster email address, and Available Addresses, click the Virtual Hosts tab and click the Edit Default Settings button. The window shown in Figure 19-3 will appear. Configure the default settings for your Web server in this window. If you add a virtual host, the settings you configure for the virtual host take precedence for that virtual host. For a directive not defined within the virtual host settings, the default value is used.

Site Configuration

The default values for the Directory Page Search List and Error Pages will work for most servers. If you are unsure of these settings, do not modify them.

Figure Site Configuration

The entries listed in the Directory Page Search List define the DirectoryIndex directive. The DirectoryIndex is the default page served by the server when a user requests an index of a directory by specifying a forward slash (/) at the end of the directory name.

For example, when a user requests the page http://www.example.com/this_directory/, they are going to get either the DirectoryIndex page if it exists, or a server-generated directory list. The server will try to find one of the files listed in the DirectoryIndex directive and will return the first one it finds. If it does not find any of these files and if Options Indexes is set for that directory, the server will generate and return a list, in HTML format, of the subdirectories and files in the directory.

Use the Error Code section to configure Apache HTTP Server to redirect the client to a local or external URL in the event of a problem or error. This option corresponds to the ErrorDocument directive. If a problem or error occurs when a client tries to connect to the Apache HTTP Server, the default action is to display the short error message shown in the Error Code column. To override this default configuration, select the error code and click the Edit button. Choose Default to display the default short error message. Choose URL to redirect the client to an external URL and enter a complete URL including the http:// in the Location field. Choose File to redirect the client to an internal URL and enter a file location under the document root for the Web server. The location must begin the a slash (/) and be relative to the Document Root.

For example, to redirect a 404 Not Found error code to a webpage that you created in a file called 404.html, copy 404.html to DocumentRoot/../error/404.html. In this case, DocumentRoot is the Document Root directory that you have defined (the default is /var/www/html/). If the Document Root is left as the default location, the file should be copied to /var/www/error/404.html. Then, choose File as the Behavior for 404 – Not Found error code and enter /error/404.html as the Location.

From the Default Error Page Footer menu, you can choose one of the following options:

• Show footer with email address — Display the default footer at the bottom of all error pages along with the email address of the website maintainer specified by the ServerAdmin directive. Refer to Section 19.3.1.1 General Options for information about configuring the ServerAdmin directive.

• Show footer — Display just the default footer at the bottom of error pages.

• No footer — Do not display a footer at the bottom of error pages.

Logging

By default, the server writes the transfer log to the file /var/log/httpd/access_log and the error log to the /var/log/httpd/error_log file.

The transfer log contains a list of all attempts to access the Web server. It records the IP address of the client that is attempting to connect, the date and time of the attempt, and the file on the Web server that it is trying to retrieve. Enter the name of the path and file in which to store this information. If the path and filename does not start with a slash (/), the path is relative to the server root directory as configured. This option corresponds to the TransferLog directive.

Figure Logging

You can configure a custom log format by checking Use custom logging facilities and entering a custom log string in the Custom Log String field. This configures the LogFormat directive. Refer to http://httpd.apache.org/docs-2.0/mod/mod_log_config.html#formats for details on the format of this directive.

The error log contains a list of any server errors that occur. Enter the name of the path and file in which to store this information. If the path and filename does not start with a slash (/), the path is relative to the server root directory as configured. This option corresponds to the ErrorLog directive.

Use the Log Level menu to set how verbose the error messages in the error logs will be. It can be set (from least verbose to most verbose) to emerg, alert, crit, error, warn, notice, info or debug. This option corresponds to the LogLevel directive.

The value chosen with the Reverse DNS Lookup menu defines the HostnameLookups directive. Choosing No Reverse Lookup sets the value to off. Choosing Reverse Lookup sets the value to on. Choosing Double Reverse Lookup sets the value to double.

If you choose Reverse Lookup, your server will automatically resolve the IP address for each connection which requests a document from your Web server. Resolving the IP address means that your server will make one or more connections to the DNS in order to find out the hostname that corresponds to a particular IP address.

If you choose Double Reverse Lookup, your server will perform a double-reverse DNS. In other words, after a reverse lookup is performed, a forward lookup is performed on the result. At least one of the IP addresses in the forward lookup must match the address from the first reverse lookup.

Generally, you should leave this option set to No Reverse Lookup, because the DNS requests add a load to your server and may slow it down. If your server is busy, the effects of trying to perform these reverse lookups or double reverse lookups may be quite noticeable.

Reverse lookups and double reverse lookups are also an issue for the Internet as a whole. All of the individual connections made to look up each hostname add up. Therefore, for your own Web server’s benefit, as well as for the Internet’s benefit, you should leave this option set to No Reverse Lookup.

Environment Variables

Sometimes it is necessary to modify environment variables for CGI scripts or server-side include (SSI) pages. The Apache HTTP Server can use the mod_env module to configure the environment variables which are passed to CGI scripts and SSI pages. Use the Environment Variables page to configure the directives for this module.

Figure Environment Variables

Use the Set for CGI Scripts section to set an environment variable that is passed to CGI scripts and SSI pages. For example, to set the environment variable MAXNUM to 50, click the Add button inside the Set for CGI Script section as shown in Figure 19-5 and type MAXNUM in the Environment Variable text field and 50 in the Value to set text field. Click OK to add it to the list. The Set for CGI Scripts section configures the SetEnv directive.

Use the Pass to CGI Scripts section to pass the value of an environment variable when the server was first started to CGI scripts. To see this environment variable, type the command env at a shell prompt. Click the Add button inside the Pass to CGI Scripts section and enter the name of the environment variable in the resulting dialog box. Click OK to add it to the list. The Pass to CGI Scripts section configures the PassEnv directive.

If you want to remove an environment variable so that the value is not passed to CGI scripts and SSI pages, use the Unset for CGI Scripts section. Click Add in the Unset for CGI Scripts section, and enter the name of the environment variable to unset. Click OK to add it to the list. This corresponds to the UnsetEnv directive.

To edit any of these environment values, select it from the list and click the corresponding Edit button. To delete any entry from the list, select it and click the cooresponding Delete button.

To learn more about environment variables in Apache HTTP Server, refer to the following:

http://httpd.apache.org/docs-2.0/env.html

Directories

Use the Directories page to configure options for specific directories. This corresponds to the <Directory> directive.

Figure Directories

Click the Edit button in the top right-hand corner to configure the Default Directory Options for all directories that are not specified in the Directory list below it. The options that you choose are listed as the Options directive within the <Directory> directive. You can configure the following options:

• ExecCGI — Allow execution of CGI scripts. CGI scripts are not executed if this option is not chosen.

• FollowSymLinks — Allow symbolic links to be followed.

• Includes — Allow server-side includes.

• IncludesNOEXEC — Allow server-side includes, but disable the #exec and #include commands in CGI scripts.

• Indexes — Display a formatted list of the directory’s contents, if no DirectoryIndex (such as index.html) exists in the requested directory.

• Multiview — Support content-negotiated multiviews; this option is disabled by default.

• SymLinksIfOwnerMatch — Only follow symbolic links if the target file or directory has the same owner as the link.

To specify options for specific directories, click the Add button beside the Directory list box. The window shown in Figure 19-7 appears. Enter the directory to configure in the Directory text field at the bottom of the window. Select the options in the right-hand list, and configure the Order directive with the left-hand side options. The Order directive controls the order in which allow and deny directives are evaluated. In the Allow hosts from and Deny hosts from text field, you can specify one of the following:

• Allow all hosts — Type all to allow access to all hosts.

• Partial domain name — Allow all hosts whose names match or end with the specified string.

• Full IP address — Allow access to a specific IP address.

• A subnet — Such as 192.168.1.0/255.255.255.0

• A network CIDR specification — such as 10.3.0.0/16

Figure Directory Settings

If you check the Let .htaccess files override directory options, the configuration directives in the .htaccess file take precedence.