IETF Logo Mail Archive

Re: [dmarc-ietf] tree walk and Org and PSD, Second WGLC for draft-ietf-dmarc-psd

John Levine <johnl@taugh.com> Sun, 22 November 2020 02:23 UTC

Return-Path: <johnl@iecc.com>
X-Original-To: dmarc@ietfa.amsl.com
Delivered-To: dmarc@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id CDB9B3A0C77 for <dmarc@ietfa.amsl.com>; Sat, 21 Nov 2020 18:23:50 -0800 (PST)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -1.85
X-Spam-Level:
X-Spam-Status: No, score=-1.85 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, HEADER_FROM_DIFFERENT_DOMAINS=0.25, SPF_PASS=-0.001, URIBL_BLOCKED=0.001] autolearn=ham autolearn_force=no
Authentication-Results: ietfa.amsl.com (amavisd-new); dkim=pass (2048-bit key) header.d=iecc.com header.b=gN36HmUi; dkim=pass (2048-bit key) header.d=taugh.com header.b=a/LpcnXL
Received: from mail.ietf.org ([4.31.198.44]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id Aijj3uvK3MIp for <dmarc@ietfa.amsl.com>; Sat, 21 Nov 2020 18:23:49 -0800 (PST)
Received: from gal.iecc.com (gal.iecc.com [IPv6:2001:470:1f07:1126:0:43:6f73:7461]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 187743A0C6B for <dmarc@ietf.org>; Sat, 21 Nov 2020 18:23:48 -0800 (PST)
Received: (qmail 22810 invoked from network); 22 Nov 2020 02:23:47 -0000
DKIM-Signature: v=1; a=rsa-sha256; c=simple; d=iecc.com; h=date:message-id:from:to:cc:subject:in-reply-to:mime-version:content-type:content-transfer-encoding:cleverness; s=5918.5fb9cbb3.k2011; bh=JgU+U7wrFBBRQlJy0wXY/b7+kEW1sLjB17uayA8uVDw=; b=gN36HmUi6gMkTpFgdGRfq3ARuNXGecGnAIsJSbiGUbwZJT5659qi1ysw1m8G3Rhz6xtk1v+54SUcGrpCOrO2IetKh/RqsHP3JAdMstjDRD+7gbnRS3Y83BRDP3Sp4BVXfyucPCOF8KGFpt6tC+ScSBLIrysrOecbBn8gUV/IUQyPtq1N9yfoLjB3UEFA7T5TRuO0NEqfLU+4ADgDmKNLrI0awiccANQzhZwMpU2NiQtU7NpMWUzwxuPcQFzy4yCBxrHxmxnYNaRffvbSGFwWigej6yBvHHouEB8RrS05n+YbsQqLdzIOwiRcoK/lIbXp840yzPVTuD1K9ogwOoGR5g==
DKIM-Signature: v=1; a=rsa-sha256; c=simple; d=taugh.com; h=date:message-id:from:to:cc:subject:in-reply-to:mime-version:content-type:content-transfer-encoding:cleverness; s=5918.5fb9cbb3.k2011; bh=JgU+U7wrFBBRQlJy0wXY/b7+kEW1sLjB17uayA8uVDw=; b=a/LpcnXLLqPelAQhqcJB4CPGnLizbNG7zd2Q13WJxqyW6cSeVKGkjPa2NkO0rH3EK3ykqhKWKGoo/ZT5DY0+l+CtAxGZpUUaolyEfNBhud7GRmVqXAhrZK9Yb04YbjWE6kDJclENOeAL9vrvKnroVsfr02BZdTbjDrgG+sgvkjD8FJtjlOwWuKzTnI/C2Su+weQGqG6zx5G2VqBfnw/3Lzr2UDkUQG7iXCaqFEPSJf5qsc7l5z8n2ux4TMH+OtKBqLiHq/8+ytfOBLf36oRzePvXe7Hv7hjNYH5vPNCQUtvRBL9SX5kdbMZc7kICsLaoR2usDDvLQOVF2avxbhKWlQ==
Received: from ary.qy ([IPv6:2001:470:1f07:1126::78:696d:6170]) by imap.iecc.com ([IPv6:2001:470:1f07:1126::78:696d:6170]) with ESMTPS (TLS1.2 ECDHE-RSA AES-256-GCM AEAD) via TCP6; 22 Nov 2020 02:23:47 -0000
Received: by ary.qy (Postfix, from userid 501) id C039627B3EF9; Sat, 21 Nov 2020 21:23:46 -0500 (EST)
Date: Sat, 21 Nov 2020 21:23:46 -0500
Message-Id: <20201122022346.C039627B3EF9@ary.qy>
From: John Levine <johnl@taugh.com>
To: dmarc@ietf.org
Cc: superuser@gmail.com
In-Reply-To: <CAL0qLwYgTiHW5XXt3PTUMOiSHV0wUt_fRLyZS7D5v1ZH_WUCNg@mail.gmail.com>
Organization: Taughannock Networks
X-Headerized: yes
Cleverness: minimal
Mime-Version: 1.0
Content-type: text/plain; charset="utf-8"
Content-transfer-encoding: 8bit
Archived-At: <https://mailarchive.ietf.org/arch/msg/dmarc/TbQsErD2-SAgU8S6suQ3C2r-aTU>
Subject: Re: [dmarc-ietf] tree walk and Org and PSD, Second WGLC for draft-ietf-dmarc-psd
X-BeenThere: dmarc@ietf.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: "Domain-based Message Authentication, Reporting, and Compliance \(DMARC\)" <dmarc.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/dmarc>, <mailto:dmarc-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/dmarc/>
List-Post: <mailto:dmarc@ietf.org>
List-Help: <mailto:dmarc-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/dmarc>, <mailto:dmarc-request@ietf.org?subject=subscribe>
X-List-Received-Date: Sun, 22 Nov 2020 02:23:51 -0000

In article <CAL0qLwYgTiHW5XXt3PTUMOiSHV0wUt_fRLyZS7D5v1ZH_WUCNg@mail.gmail.com> you write:
>Someone in DNSOP, I think, proposed doing the tree walk in the other
>direction.

Turns out that won't work because here's what you'd be checking:

> _dmarc.paypal.com
> _dmarc.baz.paypal.com
> _dmarc.bar.baz.paypal.com
> _dmarc.foo.bar.baz.paypal.com

You can have a NXDOMAIN at _dmarc.paypal.com but a TXT record at
_dmarc.bar.baz.paypal.com. You could certainly add heuristics and
check plain baz.paypal.com to see if it gives you an NXDOMAIN stop but
I have no reason to think that on average it'd actually save queries.

It is my impression that most real From: domains are pretty short. I
don't think I've ever seen one more than four labels long that wasn't
deliberately contrived. Anyone got data on that?

R's,
John
root@18.183.57.64.in-addr.arpa

v2.23.0 | Report a Bug | By Email