Forum Moderators: phranque
The first step is to do some IP filtering. Buy a database that gives you countries for IP ranges. On the first page request by a new visitor, check their IP address against the DB. If it is from a bad country, prevent them from seeing any other pages in your site.
This will stop the less tech saavy ones, but will only slow the knowledgables ones down. But, it should stop 80% of the overall attempts.