Aside from the occasional massive spam run, there’s been a fairly regular trickle of spam targeted at the comments on this blog. Dr. Dave’s excellent Spam Karma plugin takes care of nearly all of these using a combination of content filters, blacklists, form checks, signs of proxy use, and more.

On Tuesday I added IO Error’s Bad Behavior. This plugin looks at actual HTTP requests, identifies known spambots and looks for signs of cloaked bots—those that claim to be a browser like MSIE or Mozilla, but don’t act like it—and prevents them from even getting in the door. The advantage here is that you can save processing time and bandwidth on all kinds of bogus requests, not just comment spam, but address harvesting bots, referrer spam, and so on.

Maybe it’s coincidence, but Spam Karma hasn’t seen a single spam attempt since I installed Bad Behavior.

Of course, blocking bots won’t catch the occasional person who posts comment spam the old-fashioned way: by surfing to the page and filling in the form. And eventually bots will do a better job of imitating real visitors, just as phishing attacks have moved from crude, badly-spelled notes to sophisticated forgeries with real logos and disguised links. Spam Karma will still be needed for those.

But the combination looks very promising!