$remoteAddr = null;
if (isset($_SERVER['HTTP_CLIENT_IP'])) {
    $remoteAddr = $_SERVER['HTTP_CLIENT_IP'];
} else if (isset($_SERVER['HTTP_X_FORWARDED_FOR'])) {
    $remoteAddr = $_SERVER['HTTP_X_FORWARDED_FOR'];
} else {
    $remoteAddr = $_SERVER['REMOTE_ADDR'];
}

if (!in_array(@$remoteAddr , $allow)) {
    header('HTTP/1.0 403 Forbidden');
    exit('You are not allowed to access this file. Check '.basename(__FILE__).' for more information.');
}