MỘT SỐ LƯU Ý VỀ HEADER CỦA PHP

// Standardize the times & dates to UTC because people don't live in the same timezone as the server.
date_default_timezone_set("UTC");

// HSTS header (force HTTPS)
if(isset($_SERVER['HTTPS']) && $_SERVER['HTTPS'] != 'off' && $_SERVER['HTTP_HOST'] != "localhost" && $_SERVER['HTTP_HOST'] != "192.168.1.102"){
header('Strict-Transport-Security: max-age=31536000'); /* one year */
}

// Prevent pages from being displayed in iframes. Not supported by all browsers.
header('X-Frame-Options: SAMEORIGIN');