malte at 2010-11-3 10:19 wrote:
> I've recently been hit pretty hard with a nasty DDoS attack on a site of
> mine.
>
> With http://wiki.nginx.org/HttpLimitReqModule and
> http://wiki.nginx.org/HttpLimitZoneModule I was able to mitigate the
> attack reasonably well, but neither of these modules do what I'd really
> like to have done - temporarily serve only a plain 4xx or 5xx error
> message to any IP that is exhibiting clearly abusive behavior, like
> requesting the exact same page over and over again, or attempting to
> make a large amount of parallel connections (100+) at once.
limit module can also limit the concurrent request uri.

http {

limit_zone one $part_of_uri 10m;

server {
location /download/ {
set $part_of_uri "download";
limit_conn one 100;
}
}
}

I have not tested it yet, you can have a try.

> This should
> be in effect for a configurable amount of time, but just 10 minutes or
> so would have worked well against my recent attack, as each attacking
> bot only tends to attack for a few minutes before its replaced by
> another bot.
>
> So my suggestion is either adding functionality to the Limit modules, or
> adding a new DDoS module which would use a set amount of memory to keep
> tab of all IPs that have requested anything in the past 10-15 seconds,
> and can mitigate DDoS attacks by analyzing recent request and connect
> patterns by IP.
> Posted at Nginx Forum: http://forum.nginx.org/read.php?2,147105,147105#msg-147105
>
>
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> nginx mailing list
> nginx@nginx.org
> http://nginx.org/mailman/listinfo/nginx
>
>


--
Weibin Yao


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