Re: [Uta] Smallest practical MTA-STS maximum policy age?
Viktor Dukhovni <ietf-dane@dukhovni.org> Sat, 23 May 2020 19:27 UTC
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From: Viktor Dukhovni <ietf-dane@dukhovni.org>
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Subject: Re: [Uta] Smallest practical MTA-STS maximum policy age?
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On Sat, May 23, 2020 at 09:07:06PM +0200, A. Schulze wrote: > I asked a similar question last year: > https://mailarchive.ietf.org/arch/msg/uta/bnUjy9jxM_Va-lDXVtbB32zIkYI/ > Currently I use ~ 3 days as "max-age" and receive reports from google > that don't let me think they have any problem with my setting. Keep in mind that I expect implementations of MTA-STS to not refresh refresh policy caches pre-expiration in the *absence of traffic to the destination domain. So if any domain hosts users who in aggregate correspond with you less often than every 3 days, MTA-STS is completely ineffective at protecting that traffic against MiTM downgrades. Thus, my take is that MTA-STS policies with a max_age less than ~30 days are potentially ineffective, and perhaps not worth the bother. -- Viktor.
- [Uta] Smallest practical MTA-STS maximum policy a… Ivan Ristic
- Re: [Uta] Smallest practical MTA-STS maximum poli… A. Schulze
- Re: [Uta] Smallest practical MTA-STS maximum poli… Viktor Dukhovni
- Re: [Uta] Smallest practical MTA-STS maximum poli… Ivan Ristic
- Re: [Uta] Smallest practical MTA-STS maximum poli… John Levine
- Re: [Uta] Smallest practical MTA-STS maximum poli… Daniel Margolis