iframe with external page not working

Question

I'm tring to embed a webpage in an iframe, but it doesn't work at all. internal pages with relative path are displayed normally. but this simple code doesn't work:

<iframe src="http://www.google.com/"></iframe>

the place that supposed to show the iframe is just empty. i looked in the page source and there is nothing after

How can this be?

Answer 1

Google uses an X-FRAME-OPTIONS HTTP header to disallow putting their pages in iframes: https://developer.mozilla.org/en/The_X-FRAME-OPTIONS_response_header

Almost all modern browsers will refuse to put pages with this HTTP header in an iframe. There's nothing you can do about that.

Answer 2

Because the internal page had do something to prevent to be put in iframe.

Maybe a piece of javascript like that

if (window.top != window.self) {window.top.location = window.self.location;}

Answer 3

Suppose your url is www.google.com, i.e $url = "www.google.com";

$headerRes = get_headers($url);  //get the header response

foreach($headerRes as $val)
  if($val=="X-Frame-Options: SAMEORIGIN" || $val=="X-Frame-Options: DENY"){
    header("location:".$url); 
    exit; 
  }
//simply redirect to their website instead of showing blank frame

I hope I explained myself good.