Re: [ietf-smtp] MTS-STS validation when MX host points to a CNAME, violating RFC 2181 § 10.3
Viktor Dukhovni <ietf-dane@dukhovni.org> Fri, 02 April 2021 23:13 UTC
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Date: Fri, 02 Apr 2021 19:13:42 -0400
From: Viktor Dukhovni <ietf-dane@dukhovni.org>
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Subject: Re: [ietf-smtp] MTS-STS validation when MX host points to a CNAME, violating RFC 2181 § 10.3
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On Fri, Apr 02, 2021 at 11:50:04PM +0300, Kristijonas Lukas Bukauskas wrote: > > The error indicated is indeed misleading, since the problem appears > > to rather be a mismatch between the CNAME-expanded MX hostname and > > the "mx: " field of the MTA-STS policy. The certificate matches > > either name, so isn't plausibly the problem: > > > > mx.n0.lt. IN CNAME n0.lt. > > n0.lt. IN A 188.166.32.32 > > So that's the failed MX Host Validation, as described in [RFC8461], > section 4.1, that sending MTA seems to claim to be the problem. Correct? Yes, that's my interpretation of the outcome. Their MTA-STS validator detected a mismatch between the MTA-STS policy MX hostname and the CNAME-expanded MX hostname. You can test this by updating the MTA-STS policy to include both forms of the MX hostname (and sunsequently change the "id" field of the MTA-STS TXT record). If the problems go away, that'll confirm the hypothesis. > If so, what error should the reporter use, as per [RFC8460], in an > aggregated TLS report? You'd have to look at RFC8460, where I don't actually see a good fit for this case... :-( > validation-failure? That seems about the closest. -- Viktor.
- [ietf-smtp] MTS-STS validation when MX host point… Kristijonas Lukas Bukauskas
- Re: [ietf-smtp] MTS-STS validation when MX host p… Sam Varshavchik
- Re: [ietf-smtp] MTS-STS validation when MX host p… Mark Andrews
- Re: [ietf-smtp] MTS-STS validation when MX host p… John Levine
- Re: [ietf-smtp] MTA-STS validation when MX host p… Viktor Dukhovni
- Re: [ietf-smtp] MTS-STS validation when MX host p… Kristijonas Lukas Bukauskas
- Re: [ietf-smtp] MTA-STS validation when MX host p… John Levine
- Re: [ietf-smtp] MTS-STS validation when MX host p… Kristijonas Lukas Bukauskas
- Re: [ietf-smtp] MTS-STS validation when MX host p… John R Levine
- Re: [ietf-smtp] MTS-STS validation when MX host p… Kristijonas Lukas Bukauskas
- Re: [ietf-smtp] MTS-STS validation when MX host p… Sam Varshavchik
- Re: [ietf-smtp] MTS-STS validation when MX host p… John Levine
- Re: [ietf-smtp] MTS-STS validation when MX host p… Hector Santos
- Re: [ietf-smtp] MTS-STS validation when MX host p… Kristijonas Lukas Bukauskas
- Re: [ietf-smtp] MTS-STS validation when MX host p… Viktor Dukhovni
- Re: [ietf-smtp] MTS-STS validation when MX host p… Kristijonas Lukas Bukauskas
- Re: [ietf-smtp] MTS-STS validation when MX host p… Viktor Dukhovni
- Re: [ietf-smtp] MTS-STS validation when MX host p… John C Klensin
- Re: [ietf-smtp] MTS-STS validation when MX host p… Sam Varshavchik
- Re: [ietf-smtp] MTS-STS validation when MX host p… Viktor Dukhovni
- Re: [ietf-smtp] CNAME considered harmful, was MTS… John R Levine
- Re: [ietf-smtp] MTS-STS validation when MX host p… Kristijonas Lukas Bukauskas
- Re: [ietf-smtp] MTS-STS validation when MX host p… John R Levine
- Re: [ietf-smtp] MTS-STS validation when MX host p… Arnt Gulbrandsen
- Re: [ietf-smtp] CNAME considered harmful, was MTS… John C Klensin
- Re: [ietf-smtp] MTS-STS validation when MX host p… Kristijonas Lukas Bukauskas
- Re: [ietf-smtp] MTS-STS validation when MX host p… John C Klensin
- Re: [ietf-smtp] MTS-STS validation when MX host p… Mark Andrews
- Re: [ietf-smtp] on liberality, was MTS-STS_valida… John Levine
- Re: [ietf-smtp] MTS-STS validation when MX host p… Kristijonas Lukas Bukauskas
- Re: [ietf-smtp] on liberality, was MTS-STS_valida… Dave Crocker
- Re: [ietf-smtp] MTS-STS validation when MX host p… Sam Varshavchik
- Re: [ietf-smtp] MTS-STS validation when MX host p… Kristijonas Lukas Bukauskas
- Re: [ietf-smtp] MTS-STS validation when MX host p… Bron Gondwana
- Re: [ietf-smtp] MTS-STS validation when MX host p… Kristijonas Lukas Bukauskas
- Re: [ietf-smtp] MTS-STS validation when MX host p… Arnt Gulbrandsen
- Re: [ietf-smtp] MTS-STS validation when MX host p… Kristijonas Lukas Bukauskas
- Re: [ietf-smtp] MTS-STS validation when MX host p… John C Klensin
- Re: [ietf-smtp] MTS-STS validation when MX host p… Kristijonas Lukas Bukauskas