Blog comment spam has become a big problem around the globe. All kinds of ideas have been devised to try and stop it, including blacklists, banned words, removing hyperlinks and counting links.
One I’ve been using for a while, is a CAPTCHA control written by Miguel Jimenez called Clearscreen SharpHIP. This control can be added to any .Text blog, or other ASP.Net based page. A couple of the properties didn’t quite work right for me, but playing with it got it working easy enough.
CAPTCHA stands for Completely Automated Public Turing Test to Tell Computers and Humans Apart. You can see it in my comments, and it tries to prevent a computer being able to automatically pass it’s test.
On my blog alone, this little test has stopped about 10,000 attempted spam comment posts in the last month. People are using automated programs with a list of harvested blog url’s, probably from search engines, then bouncing form posts off proxies, mainly in South America, to many pages in my blog within a few seconds. But the posted forms do not even try to guess the CAPTCHA value, so fail.
So I’ve blocked heaps of comment spam, now if only I could figure out a more reliable way to stop abusive comments.