a detour DANE, was A Deep Dive on the Recent Widespread DNS Hijacking

Mark Andrews marka at isc.org
Thu Feb 28 03:22:19 UTC 2019

> On 28 Feb 2019, at 1:13 pm, John R. Levine <johnl at iecc.com> wrote:
> FYI:
>> SMTP transitioned from A to MX.
> No, it didn't.  A surprising number of real mail hosts only publish an A, and I lost the battle to say that MX shouldn't fall back to AAAA.  It does.

You have missed the point.  No one publishes A’s (or AAAA’s) because they think MX is not supported by other MTAs.

If one wanted to stop all fallback to A (and AAAA) then there needed to be a RFC that said so and set a date for
fallback to no longer be performed.

>> SPF could have been the same except people were impatient and had unrealistic expectations of how long it would take.
> Perhaps it's a generational thing.  I'm not very interested in transitions that won't happen until after I'm dead.

It required libraries to be written and for MTAs to use those new libraries.  That had started to happen.  We had name
servers at the end that were synthesising SPF records from TXT records.  One just had to wait for the OS refreshes to
occur which would got the new MTA’s deployed.  That would have mostly been done by now and I’m happy that you are not
dead.  Unfortunately I can’t prove that this would have been the course of events because it got aborted.

> R's,
> John

Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742              INTERNET: marka at isc.org

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