The X-Frame-Options response header

https://developer.mozilla.org/en-US/docs/HTTP/X-Frame-Options

 

The X-Frame-Options HTTP response header can be used to indicate whether or not a browser should be allowed to render a page in a <frame> or <iframe>. Sites can use this to avoid clickjacking attacks, by ensuring that their content is not embedded into other sites.

Using X-Frame-Options

There are three possible values for X-Frame-Options:

DENY

The page cannot be displayed in a frame, regardless of the site attempting to do so.

SAMEORIGIN

The page can only be displayed in a frame on the same origin as the page itself.

ALLOW-FROM uri

The page can only be displayed in a frame on the specified origin.

In other words, if you specify DENY, not only will attempts to load the page in a frame fail when loaded from other sites, attempts to do so will fail when loaded from the same site. On the other hand, if you specify SAMEORIGIN, you can still use the page in a frame as long as the site including it in a frame is the same as the one serving the page.

Configuring Apache

To configure Apache to send the X-Frame-Options header for all pages, add this to your site's configuration:

Header always append X-Frame-Options SAMEORIGIN

Configuring nginx

To configure nginx to send the X-Frame-Options header, add this either to your http, server or location configuration:

add_header X-Frame-Options SAMEORIGIN;

Results

When an attempt is made to load content into a frame, and permission is denied by the X-Frame-Options header, Firefox currently renders about:blank into the frame. At some point, an error message of some kind will be displayed in the frame instead.

Browser compatibility

Feature	Chrome	Firefox (Gecko)	Internet Explorer	Opera	Safari
Basic support	4.1.249.1042	3.6.9 (1.9.2.9)	8.0	10.5	4.0
ALLOW-FROM support	Not supported	18.0 (18.0) bug 690168	8.0	Not supported	WebKit bug 94836