How do I filter access to cgi-bin or other subdirectories based on the website referrer.

Here is an .htaccess directive that will allow you to filter requests to whatever sub-directory you put it in. This directive will also effectively stop any hotlinking to your site.

SetEnvIfNoCase Referer "^http://yourdomain\.com/" good_referer=1
order allow,deny
allow from env=good_referer
OnDeny http://yourdomain.com/warningpage.htm

• In this example you are specifying yourdomain as the only referrer that can access the directory that this .htaccess directive is in.
• 'http://yourdomain.com/warningpage.htm' is the path to your declined screen, you can set this to whatever you want.
• If you need help creating or using an .htaccess file please refer to this article.