Simples Assim

For Active Directory, you might want to add this to <Install Dir>/LocalSettings.php:

require_once "extensions/LdapAuthentication.php";

$wgAuth = new LdapAuthenticationPlugin();

$wgLDAPDomainNames = array(
  "fernandoribeiro.eti.br"
);

$wgLDAPEncryptionType = array(
  "fernandoribeiro.eti.br" => "clear"
);

$wgLDAPSearchStrings = array(
  "fernandoribeiro.eti.br" => "USER-NAME@fernandoribeiro.eti.br"
);

$wgLDAPServerNames = array(
  "fernandoribeiro.eti.br" => "ds.fernandoribeiro.eti.br"
);

http://www.mediawiki.org/wiki/Extension:LDAP_Authentication