I just wanted to give out another friendly shout out for ReverseDOS as a useful tool for eliminating blog comment spam and referral spam. I finally had a chance to upgrade to the latest and greatest version today as I noticed I was several versions behind. With this new version, I notice a definite performance increase in my blog. It seems to have a zippiness about it, but it could be a coincidence, too.
If you are unfamiliar with ReverseDOS-
“ReverseDOS is a very simple HttpModule that checks various parts of incoming requests against a list of crap that you don't want pushed on to your site. If ReverseDOS detects a match, it attempts to stall the requesting client for a number of seconds (specified in a .config file). During this loop, which uses virtually no server resources - and only a tiny smidgen of bandwidth, ReverseDOS checks every .3 seconds to see if the client is still connected. If the spammer disconnects, good riddance. If the spammer sticks around, they're finally rewarded with the Response Headers - containing an HTTP 403 - Access Denied Response Code. (Awwwhh tooo bad...)”
If you are having problems with blog comment spam and referral spam, I recommend checking out ReverseDOS. I have been using it for over 6 months and it really does the trick.
Learn more.
Source: David Hayden ( Florida Web Developer )