Re: DDoS attack causing bad effect on conntrack searches

Patrick McHardy
2010-04-23T13:57:44Z

Jesper Dangaard Brouer wrote:
> On Fri, 23 Apr 2010, Patrick McHardy wrote:
>
>> That sounds like a good idea. But lets what for Jesper's test results
>> before we start fixing this problem :)
>
> I will first have time to perform the tests Monday or Tuesday.
>
> BUT I have just noticed there seems to be a corrolation between
> conntrack early_drop and searches. I have upload a new graph:
>
> http://people.netfilter.org/hawk/DDoS/2010-04-12__001/conntrack_early_drop002.png

I guess that's somewhat expected when your conntrack table is full
and all you're seeing is new connection setup attempts.

First you have a search for an existing conntrack, then it attempts
to create a new one and tries to early_drop and old one.