protected static function getReferrerDns($Referrer = false)
    {
        if ($Referrer === false)
        {
            $http_referrer = isset($_SERVER['HTTP_REFERER']) ? $_SERVER['HTTP_REFERER'] : 'unknown' ;
        }
        else
        {
            $http_referrer = $Referrer;
        }
        //nur den host Anteil prüfen
        $referrer_DNS = parse_url( $http_referrer, PHP_URL_HOST );
        if ($referrer_DNS === NULL)
        {
            //try this...
            $referrer_DNS = @parse_url( 'http://'.$http_referrer, PHP_URL_HOST );
            if ($referrer_DNS === NULL ||
                $referrer_DNS === false)
            {
                //wtf...
                return false;
            }
        }
        return $referrer_DNS;
    }