Re: [tcpm] 793bis: TCP Quiet Time

Yuchung Cheng <ycheng@google.com> Thu, 19 December 2019 01:28 UTC

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From: Yuchung Cheng <ycheng@google.com>
Date: Wed, 18 Dec 2019 17:27:33 -0800
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To: Wesley Eddy <wes@mti-systems.com>
Cc: Gorry Fairhurst <gorry@erg.abdn.ac.uk>, "tcpm@ietf.org" <tcpm@ietf.org>
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Subject: Re: [tcpm] 793bis: TCP Quiet Time
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On Wed, Dec 18, 2019 at 1:33 PM Wesley Eddy <wes@mti-systems.com> wrote:
>
> I don't think I noticed anyone responding to Gorry's comment below, and
> I haven't made any alterations in the 793bis draft with regard to this
> (other than fixing some spelling mistakes).  I wanted to pull this into
> its own thread in case other people have thoughts or would like to
> discuss further what the quiet time concept's relevance is in 2020.
I probably am missing something. What's the issue of the text? Linux
to my knowledge does
not implement this quiet time.
But there are other injection attacks or basic checksum issues etc to
corrupt TCP. (Serious) application that solely relying on TCP's
integrity is signing up for troubles already ...

>
> On 8/28/2019 11:39 AM, Gorry Fairhurst wrote:
> > OLD, Section: "   The TCP Quiet Time Concept"
> > - Found this section quite amusing. Is this concept widely implemented
> > in stacks?
> > - The examples given need updated, for instance one example starts "At
> > 2 megabits/sec. it takes 4.5 hours to", clearly at 10 Gbps this line
> > of thinking becomes problematic.
> > - There is an odd sentence that states:
> > "In the absence of knowledge
> >    about the sequence numbers used on a particular connection, the TCP
> >    specification recommends that the source delay for MSL seconds before
> >    emitting segments on the connection, to allow time for segments from
> >    the earlier connection incarnation to drain from the system."
> > - how would the "source" know the MSL rather than use the Internet
> > default?
> > - To me, this section raises many questions about whether this is best
> > current practice.
>
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