On Wed, 2012-05-30 at 10:53 +0200, Christoph Paasch wrote:

On 05/30/2012 10:44 AM, Jesper Dangaard Brouer wrote:

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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.