Sample PHP

function GetIpAddress(){   
	$ip = '';
	if(!empty($_SERVER['HTTP_CLIENT_IP']))
	{
		$ip = $_SERVER['HTTP_CLIENT_IP'];
	}else if(!empty($_SERVER['HTTP_X_FORWARDED_FOR']))
	{
		$ip = $_SERVER['HTTP_X_FORWARDED_FOR'];
	}
	else
	{
		$ip = $_SERVER['REMOTE_ADDR'];
	}
	return $ip;
}