I currently have a custom implementation in PHP/mysql that keeps track of web hits and blocks those that exceed a certain rate for the same IP. I.e. if a given source IP hits the server more than X times in the last Y seconds then it will be served a redirect to a predefined location Z and the normal request processing will be aborted.
It works OK, but puts significant stress on MySQL.
So I was wondering if there is a special tool for this available? Maybe an Apache module or some kind of filter?