Re: [DNSOP] Question about usage of ip6.arpa and in-addr.arpa

"Paul Hoffman" <paul.hoffman@vpnc.org> Mon, 12 March 2018 17:37 UTC

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From: "Paul Hoffman" <paul.hoffman@vpnc.org>
To: "Roland Bracewell Shoemaker" <roland@letsencrypt.org>
Cc: dnsop@ietf.org
Date: Mon, 12 Mar 2018 10:37:27 -0700
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Subject: Re: [DNSOP] Question about usage of ip6.arpa and in-addr.arpa
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On 12 Mar 2018, at 8:58, Roland Bracewell Shoemaker wrote:

> I’m working on a document in the ACME WG that concerns methods for 
> validating control of IP addresses (draft-ietf-acme-ip) and wanted to 
> see if anyone here could provide some input on a question I had 
> regarding usage of the ip6.arpa and in-addr.arpa zones.
>
> In the original incarnation of this document one outlined method 
> revolved around requesting that a user place a TXT record containing a 
> random token in the relevant ip6.arpa or in-addr.arpa child zone for 
> the address being validated and then verifying that this record was 
> present. After reading RFC 3172 there was some concern that this would 
> not be a ‘blessed’ usage of the zones and that they should only 
> contain records that related to mapping protocol addresses to service 
> names. Because of this we reworked the method to require placing the 
> TXT record at the target of a PTR record in the relevant zone instead.
>
> After a number of discussions I’m interested in returning to the 
> original concept as it simplifies a number of use cases that this 
> document is intended to support but am still not sure whether or not 
> this would be widely considered ‘ok’ by DNS folks. Obviously 
> it’s entirely possible to do this as these child zones are delegated 
> to users and they _can_ put whatever they want in them. Does this WG 
> have strong opinions on whether we should/shouldn’t do this for 
> technical reasons or we just being a bit too strict in our reading of 
> 3172?

If the use case here is to be able to issue certificates for TLS servers 
based on the IP address instead of the domain name, creating something 
new in the DNS may be overkill. That is, why even have Section 4.1 of 
draft-ietf-acme-ip at all? What's wrong with only having direct HTTPS 
access?

--Paul Hoffman