Well, there you go. I've now finished the protection and made it public.

You can access it at for now:
http://nimmy-online.com/jj2networkfilter/
(maybe at a later date, it will be hosted elsewhere)

I intend to make regular updates with new filters by me, and other people including Overlord.

The idea of this project is to help protect the insecure jj2 from the abuse it suffers. By blocking popular methods of crashing/damaging a server.

Hopefully version 0.1 of the filter will help protect you from the crashing abuse going on, on jj2 at present.
I still recommend keeping trouble makers banned from your jj2 server using banlist, as banned users cannot do cheap tricks like renaming and mass join/quit flood. This filter, combined with a ban will stop the abuse. (A banned user can still use "ASD" to crash your server, as reported by Reptile, hence the use of the filter is also required)