1. Configure drupalauth + drupalauth4ssp
2. In simplesaml config.php file, set up baseurlpath to any valid URL (http://...
Logins do not work, because the cookie path that drupal module is trying to set will equal to /http://.. as per following code:
// get the baseurlpath
$config['baseurlpath'] = '/' . $sspConfig->getValue('baseurlpath');