Jeffrey E Burgoyne wrote:
>
> >
> > I think i've been the victim of a DOS, realised with a SYN
> Flood. I'm
> > not sure, but if yes, that's the first time.
> > Currently i try to understand what happened. I have an entry in
> > error_log which hit me on that idea:
> > "[Sat Apr 23 15:19:02 2011] [error] server reached
> MaxClients setting,
> > consider raising the MaxClients setting"
>
> Pretty sure a syn flood would not do that.
>

You are right. The linux i'm using has implmented SYN COOKIES, which is a 
protection against SYN FLOODS:

pc51332:/opt/bioinformatics/soft/apache/logs # cat 
/proc/sys/net/ipv4/tcp_syncookies
1

more information:
http://en.wikipedia.org/wiki/SYN_cookies
http://cr.yp.to/syncookies.html


Bernd

Helmholtz Zentrum München
Deutsches Forschungszentrum für Gesundheit und Umwelt (GmbH)
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