apt-get install php5-ldap

cat ldap.conf
TLS_CACERT /etc/ldap/cert.pem
TLS_CACERTFILE /etc/ldap/cert.pem

/etc/init.d/apache2 restart

cat LocalSettings.php
[...]

# CONNECTION AU LDAP

require_once( "extensions/LDAP/LdapAuthentication.php" );
$wgAuth = new LdapAuthenticationPlugin();

$wgLDAPDomainNames = array( 'adtest');
$wgLDAPServerNames = array( 'adtest' => 'monserveurldap');
$wgLDAPSearchStrings = array( 'adtest' => 'uid=USER-NAME,ou=[...],dc=fr');
$wgLDAPSearchAttributes = array( "adtest" => "uid" );
$wgLDAPBaseDNs = array( 'adtest' => 'dc=[...],dc=fr');
#$wgLDAPProxyAgent = array( 'adtest' => 'cn=anonymous,ou=[...],dc=fr');
#$wgLDAPProxyAgentPassword = array( 'adtest' => 'monpasswordsecret');
$wgLDAPEncryptionType = array( 'adtest' => 'ssl');
#$wgLDAPDebug = 3;

# RESTRICTION A UN GROUPE
$wgLDAPGroupsUseMemberOf = array( "adtest" => "true");
$wgLDAPRequiredGroups = array( "adtest" => array("cn=adtest,ou=group,dc=[...],dc=fr") );

//The objectclass of the groups we want to search for
$wgLDAPGroupObjectclass = array( "adtest"=>"posixGroup" );

//The attribute used for group members
$wgLDAPGroupAttribute = array( "adtest"=>"memberUid" );

//The naming attribute of the group
$wgLDAPGroupNameAttribute = array( "adtest"=>"cn" );

$wgLDAPUseLocal = true;
$wgMinimalPasswordLength = 1;