From: Jesper Dangaard Brouer <brouer@redhat.com>
To: christoph.paasch@uclouvain.be
Cc: netdev@vger.kernel.org, Eric Dumazet <eric.dumazet@gmail.com>,
"David S. Miller" <davem@davemloft.net>,
Martin Topholm <mph@hoth.dk>, Florian Westphal <fw@strlen.de>,
opurdila@ixiacom.com,
Hans Schillstrom <hans.schillstrom@ericsson.com>,
Andi Kleen <andi@firstfloor.org>
Subject: Re: [RFC PATCH 0/2] Faster/parallel SYN handling to mitigate SYN floods
Date: Thu, 31 May 2012 00:40:30 +0200 [thread overview]
Message-ID: <1338417630.7747.156.camel@localhost> (raw)
In-Reply-To: <4FC5DFF4.1020604@uclouvain.be>
On Wed, 2012-05-30 at 10:53 +0200, Christoph Paasch wrote:
> On 05/30/2012 10:44 AM, Jesper Dangaard Brouer wrote:
> >> >
> >> > Then the receiver will receive two SYN/ACK's for the same SYN with
> >> > different sequence-numbers. As the "SYN cookie SYN-ACK" will arrive
> >> > second, it will be discarded and seq-numbers from the first one will be
> >> > taken on the client-side.
> > I thought that the retransmitted SYN packet, were caused by the SYN-ACK
> > didn't reach the client?
>
> Or, if the SYN/ACK got somehow delayed in the network and the
> SYN-retransmission timer on the client-side fires before the SYN/ACK
> reaches the client.
That seems like a very unlikely situation, which we perhaps should
neglect as we are under SYN attack.
I will test the attack vector, if we instead of dropping the reqsk, fall
back into the slow locked path.
next prev parent reply other threads:[~2012-05-30 22:40 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-05-28 11:52 [RFC PATCH 0/2] Faster/parallel SYN handling to mitigate SYN floods Jesper Dangaard Brouer
2012-05-28 11:52 ` [RFC PATCH 1/2] tcp: extract syncookie part of tcp_v4_conn_request() Jesper Dangaard Brouer
2012-05-28 11:52 ` [RFC PATCH 2/2] tcp: Early SYN limit and SYN cookie handling to mitigate SYN floods Jesper Dangaard Brouer
2012-05-29 19:37 ` Andi Kleen
2012-05-29 20:18 ` David Miller
2012-05-30 6:41 ` Eric Dumazet
2012-05-30 7:45 ` Jesper Dangaard Brouer
2012-05-30 8:15 ` Eric Dumazet
2012-05-30 9:24 ` Jesper Dangaard Brouer
2012-05-30 9:46 ` Eric Dumazet
2012-05-30 8:03 ` Hans Schillstrom
2012-05-30 8:24 ` Eric Dumazet
2012-05-30 11:14 ` Hans Schillstrom
2012-05-30 21:20 ` Rick Jones
2012-05-31 8:28 ` Eric Dumazet
2012-05-31 8:45 ` Hans Schillstrom
2012-05-31 14:09 ` Eric Dumazet
2012-05-31 15:31 ` Hans Schillstrom
2012-05-31 17:16 ` Eric Dumazet
2012-05-28 16:14 ` [RFC PATCH 0/2] Faster/parallel SYN " Christoph Paasch
2012-05-29 20:17 ` Jesper Dangaard Brouer
2012-05-29 20:36 ` Christoph Paasch
2012-05-30 8:44 ` Jesper Dangaard Brouer
2012-05-30 8:50 ` Eric Dumazet
2012-05-30 8:53 ` Christoph Paasch
2012-05-30 22:40 ` Jesper Dangaard Brouer [this message]
2012-05-31 12:51 ` Jesper Dangaard Brouer
2012-05-31 12:58 ` Eric Dumazet
2012-05-31 13:04 ` Jesper Dangaard Brouer
2012-05-31 13:10 ` Eric Dumazet
2012-05-31 13:24 ` Jesper Dangaard Brouer
2012-05-30 4:45 ` Eric Dumazet
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