Re: [TLS] SNI from CDN to Origin (was I-D Action: draft-ietf-tls-sni-encryption-08.txt)

Rob Sayre <sayrer@gmail.com> Wed, 09 October 2019 13:04 UTC

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From: Rob Sayre <sayrer@gmail.com>
Date: Wed, 9 Oct 2019 20:04:00 +0700
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To: "Salz, Rich" <rsalz@akamai.com>
Cc: Eric Rescorla <ekr@rtfm.com>, "TLS@ietf.org" <tls@ietf.org>
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Subject: Re: [TLS] SNI from CDN to Origin (was I-D Action: draft-ietf-tls-sni-encryption-08.txt)
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On Wed, Oct 9, 2019 at 7:59 PM Salz, Rich <rsalz@akamai.com>; wrote:

>
>    - But, if I have Cloudflare (or any CDN) configured for a domain, and
>    the origin is only available via IPv6, the need for a disambiguating SNI in
>    the ClientHello from CDN to Origin is not clear.
>
>
>
> That assumes that there is a one-to-one correspondence between an origin
> and its certificate, which isn’t true.  I might have “api.example.com”
> and “new-api.example.com” at the same IP address.
>

I don't think that's quite what I'm proposing. I'm proposing (optionally)
sending the SNI with a client certificate. I agree that SNI in ClientHello
is needed to choose server certificates for IPv4, for the reason you say.

thanks,
Rob