[DNSOP] Consensus check on underscore names and draft-ietf-dnsop-rfc7816bis

[Warren Kumari <[e-mail]>]

Hi there all,

I wanted to check the consensus on a point brought up during IETF LC /
OpsDir review of draft-ietf-dnsop-rfc7816bis.

Please see:
https://mailarchive.ietf.org/arch/msg/last-call/fuDyx2as6QsK8CT_7Nvci5d7XQQ/
and
https://mailarchive.ietf.org/arch/msg/dnsop/_H4aM5AquCSRlz0Pz3ncwl7Plpk/

If resolving " _ldap._tcp.ad.example.com", once you hit the _tcp label
you are quite likely in ENT territory, and some implementations
(especially those behind firewalls / middleboxes) are still broken.
There is also a performance hit.

Version 10 of the document added:
"Another potential, optional mechanism for limiting the number of
queries is to assume that labels that begin with an underscore (_)
character do not represent privacy-relevant administrative
boundaries. For example, if the QNAME is "_25._tcp.mail.example.org"
and the algorithm has already searched for "mail.example.org", the
next query can be for all the underscore-prefixed names together,
namely "_25._tcp.mail.example.org"."

(unsurprisingly the document does a much better job of explaining the
issue than I did :-))

Viktor is suggesting that QNAME Minimization should be stopped when
you run into an underscore ("_") label, instead of this being worded
as a potential, optional mechanism.

Obviously there is a tradeoff here -- privacy vs deployment.
1: while it's **possible** that there is a delegation point at the
underscore label, (IMO) it is unlikely. If there is no delegation, you
will simply be coming back to the same server again and again, and so
you are not leaking privacy sensitive information.

2: some recursives are less likely to enable QNAME minimization
because of the non-zero ENT and slight performance issues.

What does the WG think? Does the privacy win of getting this deployed
and enabled sooner outweigh the potential small leak if there *is* a
delegation inside the _ territory of the name?

Should the advice above be strengthened to SHOULD / RECOMMENDED?

This is after IETF LC, but as the question was raised during LC, I
think it needs to be discussed and addressed.

I'd like a **clear** input, on this question only, by Tuesday August 13th.

Much thanks!
W


-- 
Perhaps they really do strive for incomprehensibility in their specs.
After all, when the liturgy was in Latin, the laity knew their place.
-- Michael Padlipsky