Re: Hit Throttling - Content Theft Prevention

["Kurt Seifried" <bt () seifried org>]

One effective strategy is to have hidden links (i.e. white text on white 
background or a 1x1 pixel image stashed somewhere) that regular browsers 
won't see at all. Have it go to a page with more links that specifically say 
"do not click this, you will be blocked," etc. These links go to a CGI, the 
CGI blocks that IP/etc (firewall rules, apache config, whatever), make sure 
you stick these in various alphabetical orders and at the top and bottom of 
the pages (many scrappers start at the top of a page or go in alphabetical 
order).

Alternatively you can monitor web logs and block anyone that requests more 
then N files in Y seconds. Also since many web scrappers initiate a new TCP 
connection for each request rate limiting SYN packets is also a quick and 
dirty way to deal with it.

The trick is to have thresholds high enough for legit web crawlers but low 
enough to catch the annoying people quickly.

You can also use Apache to redirect/serve content based on agent header, 
many people don't bother to change default agent strings, serve them a null 
site/etc. Lots of tricks.

-Kurt