As John Gruber pointed out the other day (and as many people have pointed out, many times in many fora), there are quite a few things that you can stick in Movable Type’s
mt.cfg file that are either lightly (or confusingly) documented, in the file itself or the manual, or just aren’t documented at all, anywhere. As a stopgap (and a spur), I’m going to document my understanding of some of them, starting with a pair that are partly my fault, anyway:
MT 2.66 added a throttle for comments, based on IP address. MT 3.01D extended that throttle to TrackBack pings, still based on IP address. Oops, that meant that if you received more than one ping in
ThrottleSeconds (20, by default) from the same IP address, it would be refused, even though the most likely source of two pings from the same IP address would be one legitimate post on another weblog, legitimately pinging two of your entries (“A response to Jane’s ‘Foo’ and ‘Foo, part deux'”). TrackBack spammers and flooders, of course, know about using anonymous proxies, so they don’t have any need to deliver more than one ping from a single IP address, and were unaffected.
MT 3.1x switches the TrackBack throttle from being IP address based to being simply a throttle on the number of pings: when you receive a new ping, MT looks up how many pings that weblog has received in the last hour, and in the last 24 hours, and if the number is over
OneDayMaxPings, the ping is refused with a “
403 Throttled” response. By default, if you don’t set it in
mt.cfg, you get
OneHourMaxPings 10 and
Those numbers ought to work just fine for lots of people, though I’ve noticed that in warblogger circles there’s quite a bit of use of automatic TrackBack to anything anyone links to, and quite a bit of heavy-linking, where everybody links to interesting posts, unlike a typical techblogger who would probably skip linking when she had already seen five or ten links to something. Where it’s really likely to trip people up is when they TrackBack outside the box, setting up a category to aggregate pings on a subject, like a conference or a recipe aggregator. They may need to up the numbers a bit, and a little documentation (along with moving it the hell out of a confusing text file and into a web interface) would probably come in handy.