Your ServerRoot directive should be set to /etc/httpd if you installed the RPM or /usr/local/apache (or whatever directory you chose when you compiled Apache) if you installed from the source.
ListenThe Listen directive indicates on which port you want your server to run. By default, this is set to 80, which is the standard HTTP port number. You might want to run your server on another port — for example, when running a test server that you don't want people to find by accident. Don't confuse this with real security! See the 'File System Authentication and Access Control' section for more information about how to secure parts of your web server.
User and GroupThe User and Group directives should be set to the UID and group ID (apache and group apache — a user defined specifically to run Apache. If you want to use a different UID or GID, be aware that the server runs with the permissions of the user and group set here. That means in the event of a security breach, whether on the server or (more likely) in your own CGI programs, those programs run with the assigned UID. If the server runs as root or some other privileged user, someone can exploit the security holes and do nasty things to your site. Always think in terms of the specified user running a command such as rm -rf / because that would wipe all files from your system. That should convince you that leaving apache as a user with no privileges is probably a good thing.
Instead of using names to specify the User and Group directives, you can specify them with the UID and GID numbers. If you use numbers, be sure that the numbers you specify correspond to the user and group you want and that they're preceded by the pound (#) symbol.
Here's how these directives look if specified by name:
User apache
Group apache
Here's the same specification by UID and GID:
User #48
Group #48
If you find a user on your system (other than root) with a UID and GID of 0, your system has been compromised by a malicious user.
ServerAdminThe ServerAdmin directive should be set to the address of the webmaster managing the server. This address should be a valid email address or alias, such as [email protected], because this address is returned to a visitor when a problem occurs on the server.
ServerNameThe ServerName directive sets the hostname that the server returns. Set it to a fully qualified domain name (FQDN). For example, set it to www. This is particularly important if this machine will be accessible from the Internet rather than just on your local network.
You don't need to set this unless you want a name other than the machine's canonical name returned. If this value isn't set, the server will figure out the name by itself and set it to its canonical name. However, you might want the server to return a friendlier address, such as
DocumentRootSet this directive to the absolute path of your document tree, which is the top directory from which Apache serves files. By default, it's set to /var/www/html/usage. If you built the source code yourself, DocumentRoot is set to /usr/local/apache/htdocs (if you didn't choose another directory when you compiled Apache). Prior to version 1.3.4, this directive appears in srm.conf.
UserDirThe UserDir directive disables or enables and defines the directory (relative to a local user's home directory) where that user can put public HTML documents. It's relative because each user has her own HTML directory. This setting is disabled by default but can be enabled to store user web content under any directory.
The default setting for this directive, if enabled, is public_html. Each user can create a directory called public_html under her home directory, and HTML documents placed in that directory are available as http://servername, where srm.conf.
DirectoryIndexThe DirectoryIndex directive indicates which file should be served as the index for a directory, such as which file should be served if the URL http:// is requested.
It's often useful to put a list of files here so that if index.html (the default value) isn't found, another file can be served instead. The most useful application of this is to have a CGI program run as the default action in a directory. If you have users who make their web pages on Windows, you might want to add index.htm as well. In that case, the directive would look like DirectoryIndex index.html index.cgi index.htm. Prior to version 1.3.4, this directive appears in srm.conf.
Apache Multiprocessing Modules
Apache version 2.0 and greater now uses a new internal architecture supporting multiprocessing modules (MPMs). These modules are used by the server for a variety of tasks, such as network and process management, and are compiled into Apache. MPMs enable Apache to work much better on a wider variety of computer platforms, and they can help improve server stability, compatibility, and scalability.
Apache can use only one MPM at any time. These modules are different from the base set included with Apache (see the 'Apache Modules' section later in this chapter), but are used to implement settings, limits, or other server actions. Each module in turn supports numerous additional settings, called
The internal MPM modules relevant for Linux include the following:
> mpm_common — A set of 20 directives common to all MPM modules
> prefork — A nonthreaded, preforking web server that works similar to earlier (1.3) versions of Apache
> worker — Provides a hybrid multiprocess multithreaded server
MPM enables Apache to be used on equipment with fewer resources, yet still handle massive numbers of hits and provide stable service. The worker module provides directives to control how many simultaneous connections your server can handle.
Other MPMs are available for Apache related to other platforms, such as mpm_netware
