<Location />
            AuthType Kerberos
            KrbAuthRealms xyz
            KrbServiceName HTTP/xyz
            Krb5Keytab /usr/local/apache2/conf/conf.d/drdc.keytab
            KrbMethodNegotiate on
            KrbMethodK5Passwd off
            KrbSaveCredentials on
            require valid-user
    </Location>

if ($event->getRequest()->getRequestUri() != '/user/login' && $this->currentUser->isAnonymous()) {
  if (preg_match('//comment-([d]+)/', $current_path)) {
    $destination = str_replace('/comment-', '#comment-', $current_path);
    user_cookie_save(['destination' => $destination]);
  }
  $url = '/user/login/sso';
  $response = new RedirectResponse($url);
  $event->setResponse($response);
  return;