Re: [TLS] invariant or not: one TLS connection per TCP connection?

Nico Williams <> Wed, 08 July 2020 15:08 UTC

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Date: Wed, 08 Jul 2020 10:07:53 -0500
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From: Nico Williams <>
To: Benjamin Kaduk <>
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Subject: Re: [TLS] invariant or not: one TLS connection per TCP connection?
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On Tue, Jul 07, 2020 at 09:22:24PM -0700, Benjamin Kaduk wrote:
> There's an interesting note in draft-ietf-nfsv4-rpc-tls-08 (currently
> in IESG Evaluation):
>    The protocol convention specified in the current document assumes
>    there can be no more than one concurrent TLS session per TCP
>    connection.  This is true of current generations of TLS, but might be
>    different in a future version of TLS.
> Can we envision wanting to do such a thing (e.g., with connection IDs for
> non-D TLS)?  If not, I can give them guidance that this type of statement
> is not needed.

I can see an application that starts TLS in a TCP connection, ends TLS
without also ending the TCP connection, then starts TLS again.  But
multiple concurrent TLS connections in one TCP connection?  I don't see
that happening.  Maybe with DTLS, but they are using TLS.  I would just
remove the above paragraph.