Originally Posted by rowan

I've decided to post a free tip because hotlinking sucks... use this script to send back a 401 result (authentication failed/password required). This will pop up a password prompt.

<?php
$msg = "Visit www.mydomain.com for the real pics";
header("HTTP/1.0 401 authreq");
header("WWW-Authenticate: Basic realm=\"$msg\"");
die;
?>

Use your htaccess to redirect hotlinks to that script. Replace $msg with whatever text you want to appear in the password prompt box.

Enjoy.