Apache X-Frame-Options Allow-From multiple domains

Question

I got a error when i using x-frame headers option with apache.

Header always append X-Frame-Options ALLOW-FROM site1,site2,site3

or

Header always append X-Frame-Options ALLOW-FROM=site1,site2,site3

or

Header always append X-Frame-Options ALLOW-FROM=site1
Header always append X-Frame-Options ALLOW-FROM=site2
Header always append X-Frame-Options ALLOW-FROM=site3

How could i set the X-Frame-Options: ALLOW-FROM to support more than a single domain?

Thanks!

Answer 1

It's worth noting that ALLOW-FROM is being removed from Firefox 70, and other browsers are likely to follow. You will want to use CSP's frame-ancestors directive instead, which is supported in about 95% of browsers.

Your example would then be:

Header always append Content-Security-Policy "frame-ancestors site1 site2 site3;"

EDIT: frame-ancestors overwrites X-FRAME-OPTIONS in new browsers, so theroetically you could set a value for old browsers in there and have CSP overwrite it in new browsers, but the problem is that there is no X-FRAME-OPTIONS value that will let you be embedded in multiple webpages. The only valid options are deny (not allowed anywhere), sameorigin (your website only) and allow-from (removed from modern browsers, only allowed one site anyway).

The old X-FRAME-OPTIONS value that you want to overwrite is none at all. That will allow you to embed your site in multiple other sites (all of them) and restrict it to the sites you allow in modern browsers.

If not embedding in disallowed sites is more important than embedding in allowed sites, then combine the above with:

Header always append X-Frame-Options "DENY"

That will prevent your site being embedded in all sites in about 3% of browsers, shown only in the allowed sites in 95% of browsers, and shown everywhere in the remaining 2% (even X-FRAME-OPTIONS isn't supported everywhere).