From: Bgs <bgs@bgs.hu>
To: Ric Messier <kilroy@WasHere.COM>
Cc: netfilter@lists.netfilter.org
Subject: Re: syn DDoS attack solution
Date: Fri, 01 Jun 2007 11:44:34 +0200 [thread overview]
Message-ID: <465FEA82.709@bgs.hu> (raw)
In-Reply-To: <015e01c7a3bf$64fbe7e0$2ef3b7a0$@COM>
> This is simply a SYN flood attack. It may or may not be a botnet (though
> saying botnet makes it sound sexier :-) ). A decent SYN flood attack tool
> would randomize the source address anyway.
Some more info about the attack: All IPs were real IPs otherway the tcp
handshake wouldn't have made it. The attacker IPs were also consistent.
They also new about the blocked IPs as after a new bunch of blocked IPs
we fared OK then they added another bunch new IPs... we played this for
quite some time...
All connections were in the ESTABLISHED state.
>
> You should try reading the following as a starting point:
>
> http://www.securityfocus.com/infocus/1729
>
> Your second suggestion has been implemented in the TCP/IP stack forever. The
> article above gives guidance on how to tune it in a Linux implementation.
That part is about syncookies, backlog queue and half open timeouts.
None of them applies here as all connections are legitimate in terms of
SYN packets and tcp handshake.
How is the handling of ESTABLISHED connections implemented in the TCP/IP
stack?
next prev parent reply other threads:[~2007-06-01 9:44 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-05-31 16:19 syn DDoS attack solution Bgs
2007-05-31 19:57 ` R. DuFresne
2007-06-01 9:45 ` Bgs
2007-05-31 20:08 ` Ric Messier
2007-06-01 1:20 ` Tony.Ho
2007-06-01 9:44 ` Bgs [this message]
2007-06-01 15:01 ` Ric Messier
2007-06-01 15:37 ` Bgs
2007-06-02 19:07 ` R. DuFresne
2007-06-04 14:22 ` Ric Messier
2007-06-04 17:24 ` Martin McKeay
2007-06-04 23:16 ` R. DuFresne
2007-06-05 8:29 ` Bgs
2007-06-05 14:16 ` Steven M Campbell
2007-06-05 15:22 ` ..prevention, was: " Arnt Karlsen
2007-06-05 15:40 ` Steven M Campbell
2007-06-05 15:40 ` Steven M Campbell
2007-06-05 18:34 ` Arnt Karlsen
2007-06-07 18:41 ` Martin McKeay
2007-06-08 1:40 ` Arnt Karlsen
2007-06-12 18:10 ` Martin McKeay
2007-06-12 22:44 ` R. DuFresne
2007-06-13 14:24 ` Martin McKeay
2007-06-13 17:26 ` Arnt Karlsen
2007-06-13 17:44 ` Martin McKeay
2007-06-14 19:43 ` R. DuFresne
2007-06-14 20:13 ` supportnew
2007-06-01 21:34 ` Martijn Lievaart
2007-06-01 21:37 ` Martijn Lievaart
2007-06-01 21:38 ` Ric Messier
2007-06-01 23:09 ` Ethy H. Brito
2007-06-19 18:22 ` R. DuFresne
2007-06-19 22:19 ` Robert Nichols
2007-06-19 23:02 ` Pascal Hambourg
2007-06-21 18:26 ` R. DuFresne
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