Re: [dmarc-ietf] Ticket #1 - SPF alignment

Jim Fenton <fenton@bluepopcorn.net> Sat, 30 January 2021 21:39 UTC

Return-Path: <fenton@bluepopcorn.net>
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 599783A1192 for <dmarc@ietfa.amsl.com>; Sat, 30 Jan 2021 13:39:59 -0800 (PST)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -2.099
X-Spam-Level:
X-Spam-Status: No, score=-2.099 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, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001] autolearn=ham autolearn_force=no
Authentication-Results: ietfa.amsl.com (amavisd-new); dkim=pass (1024-bit key) header.d=bluepopcorn.net
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 FHO9lgQEn63D for <dmarc@ietfa.amsl.com>; Sat, 30 Jan 2021 13:39:58 -0800 (PST)
Received: from v2.bluepopcorn.net (v2.bluepopcorn.net [IPv6:2607:f2f8:a994::2]) (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 17B313A1191 for <dmarc@ietf.org>; Sat, 30 Jan 2021 13:39:58 -0800 (PST)
DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=bluepopcorn.net; s=supersize; h=Content-Transfer-Encoding:Content-Type: MIME-Version:References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From:Sender :Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help: List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=PYBT6Je0IOnIfG6wjV2WZJ+LJZuAc8h/HgkEmX4fi84=; b=erCwNB2nfOgavuBOqHG9l61Gjd XHEx60GYDZVBypAIWuq6jRyEADWB5MUkNuVEt1DQ/y1aUj/RnXK82ChPWqkBhuRj0aUkh5nzEJK7Z Khp6fBBkDXRlNUT8GjTLeNGfVlBtnVkILTDJ0U3jbkd2NCD6MBsnFAgR9+uBdDa7lmzo=;
Received: from [2601:647:4400:1261:30d3:3a9d:66d5:72cc] (helo=[10.10.20.144]) by v2.bluepopcorn.net with esmtpsa (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from <fenton@bluepopcorn.net>) id 1l5xyG-00087T-Oa; Sat, 30 Jan 2021 13:39:57 -0800
From: "Jim Fenton" <fenton@bluepopcorn.net>
To: "John Levine" <johnl@taugh.com>
Cc: dmarc@ietf.org
Date: Sat, 30 Jan 2021 13:39:56 -0800
X-Mailer: MailMate (1.13.2r5673)
Message-ID: <66EB1EFC-753D-49FA-8652-BABB10397990@bluepopcorn.net>
In-Reply-To: <20210130212339.447316D04763@ary.qy>
References: <20210130212339.447316D04763@ary.qy>
MIME-Version: 1.0
Content-Type: text/plain; charset="UTF-8"; format=flowed; markup=markdown
Content-Transfer-Encoding: 8bit
Archived-At: <https://mailarchive.ietf.org/arch/msg/dmarc/HQbbwNSrPBoY6R2luBtenfGKIU4>
Subject: Re: [dmarc-ietf] Ticket #1 - SPF alignment
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: Sat, 30 Jan 2021 21:39:59 -0000


On 30 Jan 2021, at 13:23, John Levine wrote:

> In article <CF0B307A-C83A-4FF9-BC03-9DE28362DF3A@bluepopcorn.net> you 
> write:
>> The issue isn’t the existing use of HELO names, it’s how they 
>> could
>> be (mis-)used. The fact that a message sender can put anything there
>> makes HELO basically meaningless.
>
> This is DMARC -- the HELO domain has to match the header From: and 
> there
> has to be an SPF record that validates it.

True, but only if the MAIL FROM address is null and there isn’t a 
valid aligned DKIM signature.

> The most plausible case is that it's a bounce messsage
>
>  From: MAILER-DAEMON@mta27.foo.bar.example.com
>
> the MAIL FROM is null, HELO is mta27.foo.bar.example.com, and the SPF
> record for mta27.foo.bar.com says that IP is OK.

So in this case, why involve the HELO at all? One could just check the 
SPF record of the header From: that it’s trying to align with. Except 
that’s probably SenderID, not SPF.

-Jim