Subject: Re: High number of concurrent connections causes 2.6.4 to go berserk

From: Christopher Chan <[email-masked]>
Date: Fri, 02 Apr 2004 12:00:35 +0800

Nivedita Singhvi wrote:
> Christopher Chan wrote:
> 
>> When tcp_max_syn_backlog is set to 4096 and
>> route.max_size = 131072
>> route.gc_thresh = 65536
>>
>> the box goes berserk almost immediately after bootup due to a bounce 
>> flood hitting the box.
> 
> 
>> The below values seem to workaround whatever problem the kernel has.
>>
>> tcp_max_syn_backlog = 2048
>> route.max_size = 1048576
>> route.gc_thresh = 65536
> 
> 
> Did you try just one of the first two and see which
> one actually made a difference? I'm assuming the first,
> but that might not be the case..

Another box that has less traffic but sometimes gets ddosed by bounces 
has default settings

tcp_max_syn_backlog = 1024
route.max_size = 131072
route.gc_thresh = 8192

This box's 2.6.4 also went berserk during the ddos.

I'll try your suggestion and get back to you.

> thanks,
> Nivedita