Re: TCP window tracking patch status query for further design considerations

[Roberto Nibali <ratz@drugphish.ch>]

> Read Guido's article on which the patch is based:
> http://www.iane.nl/users/guido/papers/tcp_filtering.ps.gz

I actually did, even twice, but not carefully enough.

> The constant is a little bit bigger than the maximal possible window size
> without window scaling. The macro tries to take window scaling into
> account.

Got it.

>>Shouldn't it be (or what is the point of having MAXACKWINCONST):
>>
>>+#define MAXACKWINDOW(sender)           ((sender)->td_maxwin > MAXACKWINCONST ?
>>  MAXACKWINCONST : (sender)->td_maxwin)
> 
> 
> No, it'd make the possible ACK window smaller in the case of window
> scaling.

Makes sense now, why didn't it before?

> Those packets are either corrupted or invalid ones sent deliberately
> and would (wrongly) be reported as out of window ones.
> Most of the out of window log entries created by the earlier patch
> releases was generated because the code was not protected against such
> packets.

I understand. Thank you.

Regards,
Roberto Nibali, ratz
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