5.5. Securing the Apache HTTP Server

The Apache HTTP Server is one of the most stable and secure services that ships with Red Hat Enterprise Linux. There are an overwhelming number of options and techniques available to secure the Apache HTTP Server — too numerous to delve into deeply here.

It is important when configuring the Apache HTTP Server to read the documentation available for the application. This includes the chapter titled Apache HTTP Server in the Red Hat Enterprise Linux Reference Guide, the chapter titled Apache HTTP Server Configuration in the Red Hat Enterprise Linux System Administration Guide, and the Stronghold manuals, available at http://www.redhat.com/docs/manuals/stronghold/.

Below is a list of configuration options administrators should be careful using.

5.5.1. FollowSymLinks

This directive is enabled by default, be sure to use caution when creating symbolic links to the document root of the Web server. For instance, it is a bad idea to provide a symbolic link to /.

5.5.2. The Indexes Directive

This directive is enabled by default, but may not be desirable. To prevent visitors from browsing files on the server, remove this directive.

5.5.3. The UserDir Directive

The UserDir directive is disabled by default because it can confirm the presence of a user account on the system. To enable user directory browsing on the server, use the following directives:

UserDir enabled 
UserDir disabled root

These directives activate user directory browsing for all user directories other than /root/. To add users to the list of disabled accounts, add a space delimited list of users on the UserDir disabled line.

5.5.4. Do Not Remove the IncludesNoExec Directive

By default, the server-side includes module cannot execute commands. It is ill advised to change this setting unless absolutely necessary, as it could potentially enable an attacker to execute commands on the system.

5.5.5. Restrict Permissions for Executable Directories

Be certain to only assign write permissions to the root user for any directory containing scripts or CGIs. This can be accomplished by typing the following commands:

chown root <directory_name>
chmod 755 <directory_name>

Also, always verify that any scripts running on the system work as intended before putting them into production.