I have written two prior articles about reducing spam on your Movable Type weblog: Movable Type: Reducing Spam and Movable Type: Another Spam Reducing Technique In this article, I will show you another powerful technique to reduce your spam.
There is a free and paid version of a program called Xlogan that is available here. The program provides useful statistics regarding your website. I often download a few days worth of weblog data, and then look at the visitors tab. I look to see which ip (internet protocol) addresses have been making the most requests and which have been consuming the most bandwidth. When I find an ip address that has hit my site 500 times in one day, I then go to the raw logs, again inside of Xlogan, and look at which webpages have been hit by this particular ip address. When I see that it is trying to hit my comments and trackbacks, I know it is a spam bot. In addition to seeing which pages it accesses, I often do a WHOIS lookup to see if I can learn more about the spam bot. So I can then decide if I want to block it or not by using my .htaccess file.
I should note that I often find a family of ip addresses that originate from the same internet service provider (isp). Usually this isp is located in Eastern Europe or some other country that does not usually legitimately visit my weblog. When that is the case, I simply determine that isp's complete range of allowable addresses and block all of them.
Checking to see which ip addresses consume the most bandwidth is also helpful. The same technique applies here: determine if the ip addresses that consume most of the bandwidth are desirable guests or not.
Sometimes I will organize the ip addresses by entry page. You can do this readily by simply clicking entry page row header. As I scan down the page, I will notice that several ip addresses will hit the same comment or trackback. Obviously, several computers from different locations are trying to insert a comment or trackback. It is hard to block these bots because they are coming from all over the world. In this situation, you can rename your comment and trackback scripts, which I highlighted in my first article. This technique tends to slow them down for a while.
I also moderate all my comments. So even if the spam bot gets through my initial defenses, I must examine the entry and approve it.
I hope my techniques outlined in my three articles help you to reduce your spam load.