AuthPlugin

Authentication plugin interface.

Existing authentication plugins
There already exist authentication plugins for many cases like IMAP, LDAP and more. Category:User identity extensions lists these extensions.

Creating new authentication plugins
If you need to write your own plugin, see the source doc at MediaWiki Source Documentation

Instantiate a subclass of AuthPlugin and set $wgAuth to it to authenticate against some external source.

The default behavior is not to do anything, and use the local user database for all authentication. A subclass can require that all accounts authenticate externally, or use it only as a fallback; also you can transparently create internal wiki accounts the first time someone logs in who can be authenticated externally.

Some notes missing in the source doc:
 * The username is translated by MediaWiki before it is passed to the function: First letter becomes upper case, underscore '_' become spaces ' '.
 * If autoCreate returns true (MediaWiki should create a local account for the user) updateExternalDB( $user ) is called anyway. I guess this is to allow the plugin to synchronize the user settings with the external database. updateExternalDB must return true to make MediaWiki store the settings in the local account.
 * AuthPlugin->userExists(...) is not called when the user has already been stored in the wiki DataBase.