Re: [dane] namespace management, DANE Client Authentication draft updated

"John Levine" <johnl@taugh.com> Wed, 13 January 2016 06:42 UTC

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Date: 13 Jan 2016 06:42:21 -0000
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From: "John Levine" <johnl@taugh.com>
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Subject: Re: [dane] namespace management, DANE Client Authentication draft updated
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>>  It has very little to do with distinct transport protocols, and
>>  everything to do with avoiding name collisions.  Nobody runs POP or
>>  IMAP over UDP, but the SRV names are still _pop3._tcp and _imap._tcp.

>with the only benefit of this separation ...

The benefit of putting the service name behind a transport name is to
put the service names in a separate namespace where they don't collide
with anything else and they're already managed by IANA.

>or we inject additional labels, making the name further removed
>from identifying a DANE application at a given DNS node:
>
>    _application._tcp._client._dane.box.example. IN TLSA 3 1 1 ...
>
>because _client might be used in non-dane contexts,

No, it's _application._client._tcp.box.example, and it's because
someone might use _application in other contexts.

> and we want to distinguish TCP from UDP, 

Not really.

> ...  But what's the real benefit to all this?

You're avoiding name collisions down the road.

>James makes a plausible point about _client as a way to carve out
>a zone for clients, but because unlike SMIME/A or OPENPGPKEY the
>base domain is here typically not a zone apex, but rather a specific
>host, carving out a new zone under each host scales poorly.

Surely we don't have to review the difference between name components
and zone cuts. Nobody has proposed putting a new zone under each host
name.

R's,
John