Re: [dnssd] Zaheduzzaman Sarker's No Objection on draft-ietf-dnssd-srp-23: (with COMMENT)

[Ted Lemon <[e-mail]>]

Zaheduzzaman, thanks for the comments, sorry for the late response (you're
all probably getting tired of hearing this!)

On Thu, Aug 10, 2023 at 5:10 AM Zaheduzzaman Sarker via Datatracker <
[e-mail]> wrote:

> Thanks for working on this specification. Thanks to Joerg Ott for the
> TSVART
> review, and  yes, please respond to his comments.
>

Done, thanks!

I have following observations/questions and hope to get some responses
>
> - This document left me we with the feel that TCP is the only preferred
> transport for the DNS updates when it comes to SRP, even though UDP seems
> like
> a very potential transport for constrained devices. is this the intention?
>

We don't dis-recommend UDP. Our assumption is that for applications where
UDP is appropriate, the implementor will choose it. In fact, e.g. on Thread
networks, UDP is used for registration, although they do specify
DNS-over-TLS (specifically DNS Push) for service discovery queries.


> - Now that we have DoQ (DNS over QUIC), which have similar security/privacy
> properties as DoT and can be used for Zone transfer, and claims to be have
> same
> latency characteristic as DNS over UDP. I was wondering why QUIC a
> transport
> protocol was not considered in the specification. Is that a deliberate
> choice
> by the working group?
>

Two reasons. First, I think it's extra complexity that doesn't add any
obvious benefit—TCP is adequate to the task, and ubiquitous.  Second, when
we started writing this, QUIC was a lot less mature. Sigh.

- Specially this claim about TCP is required -
>
>     This creates the possibility of off-network spoofing, where a device
> from a
>     foreign network registers a service on the local network in order to
> attack
>     devices on the local network. To prevent such spoofing, TCP is
> required for
>     such networks.
>
>   Will this not be fulfilled with QUIC as transport?
>

It would. If at some point we come up with a reason to use QUIC, I don't
think there's any obstacle to doing it. I will confess to being pretty
naive about what functionality QUIC provides—I have a general idea, but
have never actually tried to use it. So possibly I am missing something.