Dries Buytaert

Explanation

The type of the message body, specified as a MIME type.

public means the response may be stored by all caches, including browser caches, CDNs, and shared caches.
max-age specifies the maximum amount of seconds a page is considered valid. The higher max-age, the longer a page can be cached.

The Content Security Policy (CSP) header helps prevent cross-site scripting (XSS), clickjacking, and other code injection attacks by specifying which dynamic resources are allowed to load.
default-src sets the default policy for fetching resources like JavaScript, images, CSS, fonts, AJAX requests, frames, HTML5 media.
script-src specifies valid sources for JavaScript. This includes not only URLs loaded directly into <script> elements, but also things like inline script event handlers (onclick) and XSLT stylesheets which can trigger script execution.
style-src defines what CSS stylesheets are allowed to be loaded.
media-src defines what <audio>, <video> and <track> elements are allowed to be loaded.
img-src defines what images and favicons can be loaded.
font-src defines what fonts can be loaded using CSS's font-face.
frame-src defines what <frame> and <iframe> elements can be loaded.
upgrade-insecure-requests instructs browsers to replace insecure URLs (HTTP) with secure URLs (HTTPS).

The X-Content-Type-Options header, when set to nosniff, prevents MIME type sniffing. This enhances security by ensuring browsers respect the declared Content-Type of the response, mitigating MIME confusion attacks.
The value nosniff is correctly set, providing protection against MIME type sniffing attacks.

X-Frame-Options prevents this URL from being embedded in an iframe. This protects against clickjacking attacks.
deny means that this page can never be displayed in an iframe. It's the most secure option.

This header enables the browser's built-in XSS protection. However, it's considered legacy and modern browsers may ignore it.
1 enables the browser's cross-site scripting (XSS) filtering.
mode=block instructs the browser to block the response if a XSS attack is detected, instead of sanitizing the page.

The Strict-Transport-Security header (HSTS) instructs browsers to only use HTTPS for future connections to this domain, enhancing security by preventing downgrade attacks and cookie hijacking.
max-age specifies the time, in seconds, that the browser should remember to use HTTPS only for this domain.
includesubdomains instructs the browser that all subdomains are HTTPS-only as well.

The date and time at which the request was made. A browser uses it for age calculations rather than using its own internal date and time; e.g. when comparing against Max-Age or Expires.

The page was not served from a cache.

A cookie that was sent from the server to the browser.
domain= sets the domain to which the cookie will be sent.

missing Add a Referrer-Policy header. When a visitor navigates from one page to another, browsers often pass along referrer information. The Referrer-Policy header controls how much referrer information a browser can share. This is important to configure when private information is embedded in the path or query string and passed onto an external destination.

missing Add a Permissions-Policy header. Restrict access to device features like the camera, microphone, location, accelerometer and much more.

missing Add a Cross-Origin-Embedder-Policy to specify how this page can be loaded by cross-origin resources.

missing Add a Cross-Origin-Opener-Policy header to opt-in into better browser isolation.

missing Add a Cross-Origin-Resource-Policy header to specify who can load this page.

missing Add a X-Permitted-Cross-Domain-Policies header to prevent Flash, Adobe Reader and other clients from sharing data across domains.