Mod_Auth_External is an Apache module used for authentication. The Apache HTTP
Daemon can be configured to require users to supply logins and passwords  
before accessing pages in some directories. Authentication is the process of 
checking if the password given is correct for a user. Apache has standard 
modules for authenticating out of several different kinds of databases.  
Mod_Auth_External is a flexible tool for creating authentication systems based 
on other databases.

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