I had got client's IP address by $REMOTE_ADDR or $_SERVER['REMOTE_ADDR'], but it does not work on latest version of PHP.

Following code helps you to get the correct client IP address.

function get_client_ip_env() {
	$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');
		$ipaddress = 'UNKNOWN';

	return $ipaddress;