Re: [dmarc-ietf] Comment on draft-ietf-dmarc-psd

Dave Crocker <dcrocker@gmail.com> Thu, 05 September 2019 20:22 UTC

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From: Dave Crocker <dcrocker@gmail.com>
To: "Murray S. Kucherawy" <superuser@gmail.com>
Cc: IETF DMARC WG <dmarc@ietf.org>
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Subject: Re: [dmarc-ietf] Comment on draft-ietf-dmarc-psd
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On 9/4/2019 6:28 AM, Dave Crocker wrote:
> ence my current view that:
> 
> 1. The change to DMARC should be limited to permitting the query for the 
> organization domain to be anywhere in the DNS tree, including a TLD. 
> Within DMARC this would not look like 'extra' mechanism.
> 
> 2. The mechanism that processes that query should be cast strictly as a 
> PSL enhancement, independent of DMARC.


Trying to refine things further:


    DMARC does not care about the PSL.

    What DMARC cares about is the Organizational Domain (OD), as a 
fallback when no DMARC record is found at the desired domain name.

    That is, PSL is literally outside the scope of DMARC.

    At the least, therefore, the DMARC specification should define a 
distinct interface to the outside functionality that tells DMARC where 
the OD is, which will return what suffix of the full domain name is the 
OD --  eg, getOrgDomain(full-domain) -> org-domain-suffix

    The PSL-related side of that interface should be a separate 
specification, so that changes to its behavior -- such as has been 
happening with the introduction of ODs that are TLDs or are otherwise 
'above' where DMARC has been guessing the OD to be -- are isolated from 
DMARC.

    The current problems are that DMARC has embedded too much detail 
about the PSL world, yet DMARC has no involvement in that world. The 
current proposal embeds assumptions of PSL knowledge further, rather 
than separating PSL knowledge out.


d/
-- 
Dave Crocker
Brandenburg InternetWorking
bbiw.net