Agreed. Binu, what are your thoughts on this? As Viktor said, I'm leaning
towards supporting redirects--as an implementor, it's a little extra work
(not much!) and seems to make usage much easier for many people in the
future.

On Tue, Sep 5, 2017 at 11:19 PM, Viktor Dukhovni <[email protected]>
wrote:

> On Tue, Sep 05, 2017 at 08:04:24PM +0200, Daniel Margolis wrote:
>
> > I had it in my head that a CNAME could only point to an A or AAAA, but I
> > can't find anything like that in the RFC at a quick glance, so perhaps I
> > made that up.
>
> You've made that up.  CNAMEs alias all the records for a single
> node in the DNS tree to corresponding records at some other node
> (sometimes recursively).  It is quite common, for example, to have
> CNAMES for TLSA records:
>
>  $ dig +noall +nosplit +ans +nocl +nottl -t tlsa _25._
> tcp.mx01.domeneshop.no
>  _25._tcp.mx01.domeneshop.no. CNAME mx._dane.domeneshop.no.
>  mx._dane.domeneshop.no. TLSA 3 1 1 69D43912A7968E0E7CF60EFD830D91
> 67746AA8C2B2BE7C43CC7E985F0846D485
>
> > But it sounds like you'd still prefer 302s rather than SNI (i.e. rather
> > than having the mta-sts.example.com host record point to provider.net
> and
> > have them have an HTTPS cert for that identity).
>
> To be clear, I am by no means a fan of needing to support redirect
> chasing in the MTA STS policy retrieval code.  That said however,
> as a hypothetical user of STS, I truly despise having anything to
> do with the key management headaches of third-party SNI.  So if
> you want to support delegation to the provider, then a customer
> who, like me, hates SNI should be able to operate a tiny HTTPS
> server that serves a redirect to the provider's policy URL.
>
> > Which isn't unreasonable,
> > I think; people may not have a "policy.example.com"-only certificate
> and/or
> > may not want to give one to the provider and/or the provider may not want
> > to do SNI for all their customers.
> >
> > Any other opinions on this? I think it is relatively easy to switch both
> > the text and the code to support redirects, so I don't have a strong
> > feeling myself.
>
> Your call.  However if configure-and-forget (with occasional updates
> of one's own redirect server certificate, but no constant coordination
> with the provider) delegation is important, then redirect support
> is likely needed.
>
> --
>         Viktor.
>
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