[Operators] Spam Problem And Its Simple Solution

Dave Cridland dave at cridland.net
Sat Nov 19 20:40:38 UTC 2016


On 19 November 2016 at 13:27, Krzysztof Grochocki <sirbeherit at gmail.com> wrote:
> Hello.
>
> Over the past year I received spam message only in russian language or in
> russian and english language together. I think we can block such messages
> like it is in one of polish IM - just block incoming/outgoing messages where
> is Cyrillic characters in text. At this time it's only the one way to stop
> spam. Maybe someone can write such functionality as module for ejabberd and
> prosody?

It works; it's even useful for some deployments.

https://github.com/dwd/Metre/blob/master/src/filters/unicode.cc

Setting that just to block cyrillic blocks is pretty good for me, actually.

But it's obviously not a universal solution.

SPIM is hard because they're very short messages and the intention is
to forward along to the client (more or less) instantly. So unlike
email, where we can delay to see if we get other, similar messages -
and note that even this is only useful for a large server - or delay
while we do some enhanced lookups (RBL checks on URLs, for instance)
delay is going to block a considerable amount of traffic due to the
in-order rule, which in turn introduces a potential DoS.

For personal servers - and we really want to encourage these - there's
very little we can do, and the risk of deploying a quick fix like the
above is that wide deployment would simply progress an arms race.

Dave.


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