FreeBSD TCP ignores zero window size

Andre Oppermann andre at
Wed Apr 4 10:13:17 UTC 2012

On 04.04.2012 17:03, perryh at wrote:
> Andre Oppermann<andre at>  wrote:
>> The other side is retransmitting data we have already received
>> and acknowledged ... That behavior is totally non-compliant.
> Any chance our ack of that data got dropped/lost enroute, and the
> other side is resending after timing out?

The correct ACK is retransmitted about a dozen times for
re-synchronization.  Unlikely that all of them get lost.
On top of it the RST to terminate the session has the
correct SEQ.  Something's munging the SEQ/ACK space along
the way here.


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