Re: [netconf] More complications

[Kent Watsen <[e-mail]>]

Thanks Juergen and Tom.

Henk, thanks for poking in on this thread.  Given that it appears the PSK/RPK support in TLS 1.3 is work-in-progress, Tom’s suggestion to defer modeling the TLS 1.3 part of the model at this time makes sense to me - do you agree?

If so, then it seems that we should update the model now to have a “choice statement” or “sibling-container statements", adding “if-feature” statements as needed, and then just define the TLS 1.2 solution, enabling the TLS 1.3 solution to slide-in “perfectly” via a future effort.  

Could you (or maybe Tom) help us know if a “choice statement” or “sibling-container statements” is needed?  The answer may vary for the TLS-client vs the TLS-server...

K.



> On Jun 15, 2021, at 8:18 AM, Juergen Schoenwaelder <[e-mail]> wrote:
> 
> The way TLS is used with NETCONF is defined in RFC 7589. If any of
> that needs clarification to properly support TLS 1.3, then we need to
> revise RFC 7589. Defining the proper configuration knobs should follow
> from that.
> 
> And as Kent reminds us, the scope of the TLS configuration draft is
> much wider than just NETCONF over TLS. Hence, dropping support for
> certain TLS 1.3 features, that may be essential in some use cases,
> should be done with great care. (And lets keep in mind that dropping
> standard configuration knobs just means that there are no standard
> configuration knobs, it does not mean that a certain protocol feature
> won't be used, it will just be configured using other non-standard
> means).
> 
> /js
> 
> On Tue, Jun 15, 2021 at 01:53:19PM +0200, Henk Birkholz wrote:
>> Hi all,
>> 
>> a fellow IETF'ler poked me to pay attention to this thread. Sorry for the
>> latency.
>> 
>> Hm - dropping PSK support for TLS 1.3 seems to be leaving a bunch of
>> implementations in the IoT space behind that are inching towards migration,
>> currently.
>> 
>> How urgent is this? I can certainly massage the current YANG module, but (in
>> theory) I am occupied by another SDO meeting this week.
>> 
>> Viele Grüße,
>> 
>> Henk
>> 
>> 
>> On 15.06.21 13:36, tom petch wrote:
>>> From: Kent Watsen <[e-mail]>
>>> Sent: 14 June 2021 15:27
>>> 
>>> [CC-ing Henk, to whom a question is directed to below]
>>> 
>>> 
>>> Hi Tom,
>>> 
>>>> Top posting a new and different issue.
>>> 
>>> Thanks for updating the subject line.
>>> 
>>> 
>>>> server case psk references ServerKeyExchange and psk-identity-hint neither of which exist in TLS1.3.  The client sends an extension PreSharedKeyExtension which contains a list of identities from which the server selects one as selected-identity for which the identifier is uint16 indexing into the client's list. RFC8446 s.4.2.11.
>>>> 
>>>> The client description also needs amending.
>>>> 
>>>> TLS1.2 was extended to use tickets in this area to aid session resumption; these have now gone and been replaced by this extension.  I would not suggest adding support for tickets.
>>>> 
>>>> As I may have said before, TLS 1.3 is different.
>>> 
>>> Henk, could you help with these edits?   Support for PSK and raw public key were added to draft-ietf-netconf-tls-client-server per your request and, if memory serves me, didn’t you help me with the YANG update too?   I suppose what is needed is a either a “choice” statement (with cases for 1.2 and 1.3) *or* sibling-container statements (in case it’s necessary both are configured in case, e.g., the client sends one or the other)...
>>> 
>>> <tp>
>>> Or else drop support for PSK with TLS1.3 at this time because too little is known about it outside the use for HTTP.  I am starting to see I-D about how to use TLS1.3 with application X, even for HTTP,  and I think that such an I-D will be needed for many applications with or without PSK.
>>> 
>>> Tom Petch
>>> 
>>>> Tom Petch
>>> 
>>> Kent
>>> 
>> 
>> _______________________________________________
>> netconf mailing list
>> [e-mail]
>> https://www.ietf.org/mailman/listinfo/netconf
> 
> -- 
> Juergen Schoenwaelder           Jacobs University Bremen gGmbH
> Phone: [phone]         Campus Ring 1 | 28759 Bremen | Germany
> Fax:   [phone]         <https://www.jacobs-university.de/>
> 
> _______________________________________________
> netconf mailing list
> [e-mail]
> https://www.ietf.org/mailman/listinfo/netconf