Thread:Project:Support desk/Login Authentication Issue/reply (3)

Without any extension this is nearly impossible :) It's not enough to get the username from elsewhere (i hope, that you don't edit the index.php ;)). MediaWiki povides the AuthPlugin and the hook Manual:Hooks/UserLoadFromSession with which you can implement an external authentication :)

Maybe you want to use LDAP? Then here is an extension that provides LDAP auth for MediaWiki ( i haven't tested it): Extension:LDAP_Authentication