Only allow a certain domain to access my php files

Question

I am trying to prevent a php file from being accessed directly through a browser or anything else, unless its coming from a authorised domain.

I used the php header Access-Control-Allow-Origin like this:

header('Access-Control-Allow-Origin: http://www.example.com');

But it still doesn't block direct access.

UPDATE:

I tried to .htaccess method:

order deny,allow
deny from all
allow from <your ip> 

and this one too:

<RequireAll>
    Require ip <your ip> 
</RequireAll>

I also tried using both with domain names.

With this I managed to block direct access, but I also blocked my app from accessing it too.

I get:

No 'Access-Control-Allow-Origin' header is present on the requested resource.

and I added:

header('Access-Control-Allow-Origin: myappdomain.com');

Still not working.

Answer 1

How about using $_SERVER['HTTP_REFERER'] ?
Sample code:

if($_SERVER['HTTP_REFERER'] !== 'gooddomain.com'){
    die('Unauthorized access');
}

Although this can be manipulated or altered quite easily, unless you control both the sending and the receiving server there isn't much more you can do.