Re: [Dots] TR: [IANA #1181897] expert review for draft-ietf-dots-signal-call-home (service-names-port-numbers)

[[e-mail]]

Hi Jon, 

Please see inline. 

Cheers,
Med

> -----Message d'origine-----
> De : Jon Shallow [mailto:[e-mail]]
> Envoyé : vendredi 13 novembre 2020 10:54
> À : BOUCADAIR Mohamed TGI/OLN <[e-mail]>;
> [e-mail]; Benjamin Kaduk <[e-mail]>
> Objet : RE: [Dots] TR: [IANA #1181897] expert review for draft-ietf-
> dots-signal-call-home (service-names-port-numbers)
> 
> Hi All,
> 
> I strongly recommend that we continue to press for separate ports.
> 
> We have here 2 applications, very little overlap in functionality
> using a common protocol (DOTS/CoAP/(D)TLS) - no real different to
> say, mail and web both using a common protocol - TLS.
> 
> If they insist on a single port, then we would have to do at least
> one of
> 
> a) Use different IP addresses albeit probably on the same host

[Med] We can't force that.

> b) De-multiplex incoming data to IP:port and steer to appropriate
> application and transmit responses accordingly - a sort of DOTS
> proxy front-ending things

[Med] I'm not sure to get this one. Based on which criteria we can steer the traffic?  

> c) Merge the 2 applications into a single entity and enhance DOTS
> protocol

[Med] We could define an explicit message that requests "role reversal" once the (D)TLS session is created but this is might not be efficient especially when the session is to be established/reestablished during attack times.   

> d) Spawn off the appropriate instance when a new connection comes in
> - but we are UDP here.
> e) Rely on server (and call-home) discovery to provide an
> alternative port.

[Med] We do mention this one in the draft. The default port is used only when no config is available. To the question why discovery is not sufficient, the response is the same as the one we provided when we got assigned 4646.

> 
> Note that the CoAP library I am using is not multi-thread safe which
> complicates things further.

[Med] Good point to know. 

> 
> Regards
> 
> Jon
> 
> > -----Original Message-----
> > From: Dots [mailto:[e-mail]] On Behalf Of
> > [e-mail]
> > Sent: 13 November 2020 08:06
> > To: [e-mail]; Benjamin Kaduk ([e-mail])
> > Subject: [Dots] TR: [IANA #1181897] expert review for
> > draft-ietf-dots-signal-call- home (service-names-port-numbers)
> >
> > Hi All,
> >
> > We received this reply from the port expert.
> >
> > We do have an appendix that explains why we do need a port number:
> > demux two distinct services (one to handle mitigation and another
> one
> > to request mitigations). When a DTLS connection is received, the
> node
> > hosting both the base and call home has no means to determine
> which
> > role it needs to proceed with.
> >
> > I'm not sure how we can follow the suggestion to "use two
> different
> > messages on the same port" especially that we don't define the
> > transport but rely upon existing ones.
> >
> > Unless there are other tweaks not already discarded in the past, I
> > suggest we maintain our request.
> >
> > Thoughts?
> >
> > Cheers,
> > Med
> >
> > -----Message d'origine-----
> > De : Sabrina Tanamal via RT [mailto:[e-mail]]
> > Envoyé : jeudi 12 novembre 2020 23:43
> > Cc : [e-mail]; BOUCADAIR Mohamed TGI/OLN
> > <[e-mail]>; [e-mail];
> > [e-mail]; [e-mail]; [e-mail];
> > [e-mail] Objet : [IANA #1181897] expert review for
> > draft-ietf-dots-signal-call-home
> > (service-names-port-numbers)
> >
> > Dear Authors,
> >
> > We have a response from the IESG-designated port expert:
> >
> > I do not see sufficient reason for a second port assignment to be
> made
> > for this single system. At best, they should just use two
> different
> > messages on the same port.
> >
> > This request should not be considered in isolation; it is coupled
> to
> > https://tools.ietf.org/html/draft-ietf-dots-server-discovery.
> >
> > One service, one port.
> >
> > ===
> >
> > Best regards,
> >
> > Sabrina Tanamal
> > Senior IANA Services Specialist
> >
> > _________________________________________________________________
> > ________________________________________________________
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_________________________________________________________________________________________________________________________

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