How to limit display of iframe from an external site to specific domains only

Question

I operate a service where a client\'s content is prepared and displayed in an iframe. The client then copies a rudimentary iframe html tag and pastes it into their web page.

Answer 1

Sounds like a check that is better made server side - you can check the iFrame markup against a list of valid domain names (or parent domain names) and reject it if they are invalid.

You could do all of the above in javascript, before injecting the iFrame into the page, but if javascript is off, your validation will not work, not to mention that with development tools on the client any javascript can be modified.