add this to your CMS index file to protect a file

gistfile1.php

if($_SERVER['SERVER_ADDR'] == '127.0.0.1') {

	$username = 'username';
  	$password = 'password';

	if (!(isset($_SERVER['PHP_AUTH_USER']) && ($_SERVER['PHP_AUTH_USER']==$username && $_SERVER['PHP_AUTH_PW']==$password))) 	{
    		header('WWW-Authenticate: Basic realm="This site is protected"');
    		header('HTTP/1.0 401 Unauthorized');
    		// Fallback message when the user presses cancel / escape
    		echo 'Access denied';
    	exit;
  	}
}