<?php 
echo "PHP_SELF : " . $_SERVER['PHP_SELF'] . "<br />"; 
echo "GATEWAY_INTERFACE : " . $_SERVER['GATEWAY_INTERFACE'] . "<br />"; 
echo "SERVER_ADDR : " . $_SERVER['SERVER_ADDR'] . "<br />"; 
echo "SERVER_NAME : " . $_SERVER['SERVER_NAME'] . "<br />"; 
echo "SERVER_SOFTWARE : " . $_SERVER['SERVER_SOFTWARE'] . "<br />"; 
echo "SERVER_PROTOCOL : " . $_SERVER['SERVER_PROTOCOL'] . "<br />"; 
echo "REQUEST_METHOD : " . $_SERVER['REQUEST_METHOD'] . "<br />"; 
echo "REQUEST_TIME : " . $_SERVER['REQUEST_TIME'] . "<br />"; 
echo "REQUEST_TIME_FLOAT : " . $_SERVER['REQUEST_TIME_FLOAT'] . "<br />"; 
echo "QUERY_STRING : " . $_SERVER['QUERY_STRING'] . "<br />"; 
echo "DOCUMENT_ROOT : " . $_SERVER['DOCUMENT_ROOT'] . "<br />"; 
echo "HTTP_ACCEPT : " . $_SERVER['HTTP_ACCEPT'] . "<br />"; 
echo "HTTP_ACCEPT_CHARSET : " . $_SERVER['HTTP_ACCEPT_CHARSET'] . "<br />"; 
echo "HTTP_ACCEPT_ENCODING : " . $_SERVER['HTTP_ACCEPT_ENCODING'] . "<br />"; 
echo "HTTP_ACCEPT_LANGUAGE : " . $_SERVER['HTTP_ACCEPT_LANGUAGE'] . "<br />"; 
echo "HTTP_CONNECTION : " . $_SERVER['HTTP_CONNECTION'] . "<br />"; 
echo "HTTP_HOST : " . $_SERVER['HTTP_HOST'] . "<br />"; 
echo "HTTP_REFERER : " . $_SERVER['HTTP_REFERER'] . "<br />"; 
echo "HTTP_USER_AGENT : " . $_SERVER['HTTP_USER_AGENT'] . "<br />"; 
echo "HTTPS : " . $_SERVER['HTTPS'] . "<br />"; 
echo "REMOTE_ADDR : " . $_SERVER['REMOTE_ADDR'] . "<br />"; // ไอพีเน็ตของเรา
echo "REMOTE_HOST : " . $_SERVER['REMOTE_HOST'] . "<br />"; 
echo "REMOTE_PORT : " . $_SERVER['REMOTE_PORT'] . "<br />"; 
echo "REMOTE_USER : " . $_SERVER['REMOTE_USER'] . "<br />"; 
echo "REDIRECT_REMOTE_USER : " . $_SERVER['REDIRECT_REMOTE_USER'] . "<br />"; 
echo "SCRIPT_FILENAME : " . $_SERVER['SCRIPT_FILENAME'] . "<br />"; 
echo "SERVER_ADMIN : " . $_SERVER['SERVER_ADMIN'] . "<br />"; 
echo "SERVER_PORT : " . $_SERVER['SERVER_PORT'] . "<br />"; 
echo "SERVER_SIGNATURE : " . $_SERVER['SERVER_SIGNATURE'] . "<br />"; 
echo "PATH_TRANSLATED : " . $_SERVER['PATH_TRANSLATED'] . "<br />"; 
echo "SCRIPT_NAME : " . $_SERVER['SCRIPT_NAME'] . "<br />"; 
echo "REQUEST_URI : " . $_SERVER['REQUEST_URI'] . "<br />"; 
echo "PHP_AUTH_DIGEST : " . $_SERVER['PHP_AUTH_DIGEST'] . "<br />"; 
echo "PHP_AUTH_USER : " . $_SERVER['PHP_AUTH_USER'] . "<br />"; 
echo "PHP_AUTH_PW : " . $_SERVER['PHP_AUTH_PW'] . "<br />"; 
echo "AUTH_TYPE : " . $_SERVER['AUTH_TYPE'] . "<br />"; 
echo "PATH_INFO : " . $_SERVER['PATH_INFO'] . "<br />"; 
echo "ORIG_PATH_INFO : " . $_SERVER['ORIG_PATH_INFO'] . "<br />"; 
?> 

function get_client_ip() {
     $ipaddress = '';
     if ($_SERVER['HTTP_CLIENT_IP'])
         $ipaddress = $_SERVER['HTTP_CLIENT_IP'];
     else if($_SERVER['HTTP_X_FORWARDED_FOR'])
         $ipaddress = $_SERVER['HTTP_X_FORWARDED_FOR'];
     else if($_SERVER['HTTP_X_FORWARDED'])
         $ipaddress = $_SERVER['HTTP_X_FORWARDED'];
     else if($_SERVER['HTTP_FORWARDED_FOR'])
         $ipaddress = $_SERVER['HTTP_FORWARDED_FOR'];
     else if($_SERVER['HTTP_FORWARDED'])
         $ipaddress = $_SERVER['HTTP_FORWARDED'];
     else if($_SERVER['REMOTE_ADDR'])
         $ipaddress = $_SERVER['REMOTE_ADDR'];
     else
         $ipaddress = 'UNKNOWN';

     return $ipaddress; 
}

เพิ่มอันนี้เข้าไปอีกตัว
HTTP_X_CLUSTER_CLIENT_IP

public static function real_ip($default = '0.0.0.0', $exclude_reserved = false)
	{
		static $server_keys = null;

		if (empty($server_keys))
		{
			$server_keys = array('HTTP_CLIENT_IP', 'REMOTE_ADDR');
			if (\Config::get('security.allow_x_headers', false))
			{
				$server_keys = array_merge(array('HTTP_X_CLUSTER_CLIENT_IP', 'HTTP_X_FORWARDED_FOR'), $server_keys);
			}
		}

		foreach ($server_keys as $key)
		{
			if ( ! static::server($key))
			{
				continue;
			}

			$ips = explode(',', static::server($key));
			array_walk($ips, function (&$ip) {
				$ip = trim($ip);
			});

			$ips = array_filter($ips, function($ip) use($exclude_reserved) {
				return filter_var($ip, FILTER_VALIDATE_IP, $exclude_reserved ? FILTER_FLAG_NO_PRIV_RANGE | FILTER_FLAG_NO_RES_RANGE : null);
			});

			if ($ips)
			{
				return reset($ips);
			}
		}

		return \Fuel::value($default);
	}