Chapter 19. Apache Modules

Modules are a key part of Apache. They provide much of the functionality administrators expect in a modern web server, including user tracking, CGI scripting, authentication, SSL, etc. The set of modules distributed with Apache can be divided into a number of groups. Core modules provide the set of directives that are always available to Apache. The Base modules provide a common set of features for the server and are compiled in by default. You have to manually deselect them during compilation to not install them. The Extension modules comprise another set of common and useful server features, but are not required for every server setup. Therefore, they are not compiled by default. The remaining modules are classified as Experimental; they are either not completed to specification, or introduce instability to some environments.

This chapter contains information about the Base and Extension modules and their directives. The modules are present in versions 1.3 and 2.0, and differences in support are noted per version. Table 19-1 shows the Apache modules described in this chapter.

Table 19-1. Standard Apache modules

Module	Compiled	Description
mod_access		Access control
mod_actions		CGI scripting
mod_alias		Aliasing and filesystem mapping
mod_asis		Provides for .asis (as is) files
mod_auth		User authentication
mod_auth_anon		Anonymous user authentication
mod_auth_db		User authentication with DB files. (Apache 1.1 to 1.3)
mod_auth_dbm		User authentication with DBM files
mod_autoindex		Automatic directory listings
mod_cern_meta		Support for CERN metafiles
mod_cgi		Execution of CGI scripts
mod_cgid		Execution of CGI scripts with external daemon (Apache 2.0 and up)
mod_dir		Simple directory handling
mod_dav		Support for WevDAV (Apache 2.0 and up)
mod_deflate		Compress content sent to the client (Apache 2.0 and up)
mod_env		Environment variable handling
mod_example		Example of Apache API usage
mod_expires		Automatic expire headers
mod_headers		Modification of HTTP response headers
mod_imap		Image map handling
mod_include		Server-side includes
mod_info		Server information
mod_isapi		Support for ISAPI extensions in Windows
mod_log_config		Configurable logging
mod_logio		Logs input and output bytes (Apache 2.0 and up)
mod_mime		MIME handling
mod_mime_magic		MIME handling via magic numbers
mod_negotiation		Content negotiation
mod_proxy		Proxy capabilities
mod_rewrite		URL rewriting
mod_setenvif		Conditional setting of environment variables
mod_so		Dynamic loading of modules and libraries
mod_speling		Spelling corrections
mod_ssl		Secure transaction over SSL (Apache 2.0 and up)
mod_status		Server status pages
mod_suexec		Select user and group for CGI (Apache 2.0 and up)
mod_userdir		User HTML directories
mod_unique_id		Unique server request identifiers
mod_usertrack		User tracking (cookies)
mod_vhost_alias		Dynamic virtual host configuration (Apache 2.0 and up)

This chapter presents an overview of the runtime directives used with the Apache modules. Each of the directives listed in this chapter are grouped in association with the module they relate to.