public static function get_client_ip() {
        $ipaddress = '';
        if (getenv('HTTP_CLIENT_IP')) $ipaddress = getenv('HTTP_CLIENT_IP');
        else if (getenv('HTTP_X_FORWARDED_FOR')) $ipaddress = getenv('HTTP_X_FORWARDED_FOR');
        else if (getenv('HTTP_X_FORWARDED')) $ipaddress = getenv('HTTP_X_FORWARDED');
        else if (getenv('HTTP_FORWARDED_FOR')) $ipaddress = getenv('HTTP_FORWARDED_FOR');
        else if (getenv('HTTP_FORWARDED')) $ipaddress = getenv('HTTP_FORWARDED');
        else if (getenv('REMOTE_ADDR')) $ipaddress = getenv('REMOTE_ADDR');
        else $ipaddress = 'UNKNOWN';
        return $ipaddress;
    }