Block users coming from a particular URL after clicking banner ad
<p>I want to block users coming from a particular URL. our adbanner is shown in many websites. People who click our  banner on a website are directed to our registration page. I don't want the page to be shown for people who click our ad on a particular website say <a href="http://abc.com" rel="nofollow">http://abc.com</a>. How can I implement this restriction ?
Thanks in advance </p>
