On Thursday 27 January 2005 21:18, Jonathan Stone wrote:
> >3) In the "very old ack" case that itojun added, send an ACK before
> > dropping the segment, to try to update the other side's send sequence
> > number.
>
> If Itojun is trying to kludge up a defense against the long-lived-TCP
> (BGP) sequence-number guessing attacks, then sending an ACK with
> current sequenc number defeats the purpose of the change.  I would
> therefore not send the ACK.

Not.  If the sender is able to receive this ack and get the current sequence 
numbers, then they could have gotten them anyway.