[dns-operations] Quad9 DNSSEC Validation?

Scott Morizot tmorizot at gmail.com
Mon Mar 1 21:30:53 UTC 2021

On Mon, Mar 1, 2021 at 9:40 AM John Todd <jtodd at quad9.net> wrote:

> TL;DR:
> - We agree: Quad9 should be more transparent about it's NTA list and
> policy; that will be forthcoming, and we hope others will do the same. It’s
> time to do that.
> - NTAs are terrible, and we wish they didn't have to exist, but... they
> do, at the moment, and not just for Quad9
> - Is anyone interested in being a central NTA manager so this can be less
> arbitrary and fractured?
> - If not, can we develop a best practice on publishing NTAs and NTA
> policies for everyone to follow?
> - Better yet: Can we (recursive DNS operators) agree to just get rid of
> NTAs entirely?
> For my personal use, I have pretty much always run my own nameservers.
However, as a typical Internet user, my choices for recursive
nameservers other than one I run are pretty limited. I can use my ISP's
nameservers, which are typically only available to customers. And I can use
one of the well-known public DNS providers. Right now, that's primarily
Google, OpenDNS, Cloudflare, and Quad9. Yes, I know there are more that can
be located, but at some juncture if someone is savvy enough to research
that far, they can probably just run their own recursive nameserver. It's
not rocket science at the small, residential personal network level. It's
at scale that DNS gets much more complex. For most people, the choice boils
down to their ISP's recursive nameservers or one of the well-known public
DNS sources. At this juncture, those four all validate DNSSEC. I have no
idea what the particular incentives are behind the free services, but it
doesn't seem like a huge universe. My ISP is one of the ones other than
Comcast that now performs DNSSEC validation. So if I were using a public
service and resolution failed there, it would fail at my ISP's nameservers
too. As a recursive DNS operator in the enterprise/government sphere who
has never employed NTAs for Internet queries, I have no problem with people
getting rid of them. However, we can point to FISMA security requirements
(NIST SP 800-53 control SC-21) which is reflected in our Cybersecurity IRM
as justification. It's a security and compliance issue and the way
government functions is inherently different with different incentives than
business models.

But I'm not sure there are all that many parties who would need to agree to
eliminate NTAs to normalize that approach. Again, though, my perspective is
a different one.

> So, first things first. The comments about a lack of publishing the NTA
> list are correct and we are falling short on that, and that is something we
> need to remedy. It's been on the "to-do" list, but has not been high enough
> to score for completion in our constantly large list of operational work
> with (relatively) small non-profit resources, but we'll change that. We’ll
> have our NTA list up on our website shortly after with some discussion of
> policy with the team here of what gets domains put on that list and
> how/when they should be taken off. We've recently undertaken extensive
> review of our privacy policies and transparency statements, and NTAs seem
> to be a reasonable thing to add to the list of review and publication. The
> addition process for NTAs to date has been subjective, and that needs to be
> better documented and published, and the domains listed in a way that can
> be discovered on our website. This needs to be done both as assurance to
> our users as to the exceptions to our validation claims, and also hopefully
> as an additional indication to domain operators who are important enough to
> except but also broken enough to fail validation.

Thank you. That addresses my issue. I would prefer to see the DNSSEC
information we publish consumed and enforced of course, and I was surprised
by the breadth of the exclusion, but as long as those who use a public
service know what they are getting and in this instance that domains used
primarily by the US government are excluded from validation, I have no
issue with whatever approach any such service uses.

> As we will be undergoing this transparency process, we would hope that
> others providing similar DNS recursive services would hope to do the same.
> Kudos to Cisco for calling that out as an intended NTA publication concept
> in their policy (
> https://learn-umbrella.cisco.com/i/1202769-support-for-dnssec-in-umbrella/0?)
> but we're unable to find this dashboard (sorry if we've just not dug deeply
> enough, or perhaps it's only available to paying customers.) We're not able
> to find even a policy statement for Cloudflare, Google, Comcast, Deutsche
> Telekom, KPN, Reliance Jio or others who are actively enforcing strict
> validation about what NTAs they have in place or when they are
> added/deleted, though there are certainly discussions about some of those
> providers having NTAs in threads similar to this one over time. Perhaps
> some of these providers have public NTA lists, but some quick searching did
> not find anything obvious - does anyone have pointers?
Here, I have to admit that I've generally not looked for such a list
because most of the time my testing of various public services is limited
to ensuring our domains are being properly validated when validation is
advertised. I also don't check ISPs outside the US. And my checking has
been sporadic. I also subscribe to various groups so I see some of them,
like Google Public DNS, responding to inquiries. This is the first time I
have ever encountered a negative trust anchor for the entire .gov gTLD.
Until someone pointed it out earlier in the thread, it didn't even occur to
me to check for that. My initial assumption was that it was an NTA for
irs.gov specifically.

> So, let’s all do this.(*) That will help people understand the scope of
> the problem, and we hope that it will get the discussion moving again. We
> would actually like to see some sort of "best practices" policy for NTA
> implementation, or at least NTA declaration, or perhaps our publication of
> our methods might move towards that as an agreeable first attempt at a best
> practice. Ideally, the best possible case would to be having no NTAs at
> all, but it's clear that most resolver operators have NTAs in place in a
> non-zero volume. We hope we can come up with a way to use them as levers to
> improve security with those domains, rather than just create hidden
> exceptions.
> Is anyone else here interested in the discussion about a standardized
> method of NTA publication and policy statement publication? The discussions
> about privacy policy went exceptionally well in that regard leading to
> RFC8932, though this topic of NTA transparency is a much smaller slice of
> policy framing. There perhaps may be some other better forum in which to
> move that discussion, though making it an IETF Draft discussion or BCP may
> be somewhat heavy for the need.
Well, NTAs are not part of the protocol standard at all, so I'm not sure
how receptive the IETF dnsop group would be. I remember the informational
RFC discussion being somewhat controversial at the time and approved more
with an attitude of "if you're going to do this bad thing, at least try to
adhere to these principles".

(*) Can we short-circuit this whole issue, perhaps? Have we reached a world
> where strict validation of DNSSEC is now viable, with no NTAs? I think it
> is worth evaluating, because even if that day is not today or this year
> then when would it be? How could we determine the viability of such a
> shift? If NTA elimination was a DNS Flag Day event for strict-validating
> recursive operators, where some significant portion of the largest
> resolvers agreed on that policy, I know that would make everyone here
> exceptionally happy. This whole subjective-decision issue could go away and
> functional comparisons against other large recursive resolver arrays (open
> or closed) would not have any differences in DNSSEC results, at least none
> that would be able to be blamed on "manual exceptions." I think this
> deserves to be broken out into a separate thread of discussion if anyone
> wishes to continue the conversation, as this is not a Quad9-specific
> aspiration.

Comcast had a particular storm where the media reported incorrectly that
they were "blocking NASA" during a significant NASA event with a lot of
eyes on it. I understand the particular pain they encountered in that
event. I don't believe we are in that world or that stage of deployment
anymore. As I noted, we have never employed NTAs for Internet recursive DNS
resolution for our population of ~100k employees and contractors and we
have been enforcing DNSSEC validation at our perimeter since 2012. (The
precise number fluctuates over time and I don't usually bother to keep
track of it.) Our employees, however, are a captive audience. On our
network, we are the only DNS provider they are allowed to use. And we have
multiple firewalls and ACLs throughout our network enforcing that level of
restricted access.

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