$ch = curl_init();
curl_setopt($ch, CURLOPT_URL,'https://mc.yandex.ru/metrika/tag.js');
$fp = fopen('https://site.ru/tag.js', 'w');
curl_setopt($ch, CURLOPT_FILE, $fp);
curl_exec ($ch);
curl_close ($ch);
fclose($fp);
header('Content-Description: File Transfer');
header('Content-Type: application/octet-stream');
header('Content-Disposition: attachment; filename="'.$file_name.'"');
header('Content-Transfer-Encoding: binary');
header('Expires: 0');
header('Cache-Control: must-revalidate, post-check=0, pre-check=0');
header('Pragma: public');
header('Content-Length: ' . filesize($file_url)); //Absolute URL
ob_clean();
flush();
readfile($file_url); //Absolute URL
exit();