get ip request client by PHP

get_ip_client.php

    /**
     * Lấy địa chỉ ip của client
     */
    protected function get_client_ip()
    {
        $ipaddress = '';
        if (isset($_SERVER['HTTP_CLIENT_IP']) && $_SERVER['HTTP_CLIENT_IP']) {
            $ipaddress = $_SERVER['HTTP_CLIENT_IP'];
        } else if (isset($_SERVER['HTTP_X_FORWARDED_FOR']) && $_SERVER['HTTP_X_FORWARDED_FOR']) {
            $ipaddress = $_SERVER['HTTP_X_FORWARDED_FOR'];
        } else if (isset($_SERVER['HTTP_X_FORWARDED']) && $_SERVER['HTTP_X_FORWARDED']) {
            $ipaddress = $_SERVER['HTTP_X_FORWARDED'];
        } else if (isset($_SERVER['HTTP_FORWARDED_FOR']) && $_SERVER['HTTP_FORWARDED_FOR']) {
            $ipaddress = $_SERVER['HTTP_FORWARDED_FOR'];
        } else if (isset($_SERVER['HTTP_FORWARDED']) && $_SERVER['HTTP_FORWARDED']) {
            $ipaddress = $_SERVER['HTTP_FORWARDED'];
        } else if (isset($_SERVER['REMOTE_ADDR']) && $_SERVER['REMOTE_ADDR']) {
            $ipaddress = $_SERVER['REMOTE_ADDR'];
        } else {
            $ipaddress = 'UNKNOWN';
        }

        return $ipaddress;
    }