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Versions: 00 01 02 03 04                                                
Network Working Group                                         M. Andrews
Internet-Draft                                                       ISC
Expires: May 11, 2014                                   November 7, 2013


                         Updating Parent Zones
               draft-andrews-dnsop-update-parent-zones-04

Abstract

   DNS UPDATE was developed to allow DNS zones to be updated.

   There is a perception that UPDATE cannot be used in conjuction with
   the Registry, Registar, Registrant (RRR) model to update a zone.

   This document explains how UPDATE can be used in the RRR model.

Status of this Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
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   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
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   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on May 11, 2014.

Copyright Notice

   Copyright (c) 2013 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
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   described in the Simplified BSD License.



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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . 3
   2.  Requirements  . . . . . . . . . . . . . . . . . . . . . . . . . 3
   3.  Translation . . . . . . . . . . . . . . . . . . . . . . . . . . 3
   4.  Authentication  . . . . . . . . . . . . . . . . . . . . . . . . 4
   5.  Direct to Registrar . . . . . . . . . . . . . . . . . . . . . . 4
   6.  Indirect to Registrar . . . . . . . . . . . . . . . . . . . . . 4
   7.  UPDATE Server Discovery . . . . . . . . . . . . . . . . . . . . 5
   8.  Security Considerations . . . . . . . . . . . . . . . . . . . . 6
   9.  Normative References  . . . . . . . . . . . . . . . . . . . . . 6
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . . . 6







































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1.  Introduction

   UPDATE [RFC2136] is designed to update any zone in the DNS.  This
   includes updating delegating NS records, glue address records and DS
   records.

   While UPDATE is primarily designed to UPDATE a zone directly there in
   no reason why UPDATE requests cannot be translated to the EPP
   requests to perform the changes.

   This would provide a uniform model to update parent zone regardless
   of where they are in the DNS hierarchy or whether the zone is signed
   or not.


2.  Requirements

   This document was written with the following requirements in mind:

   o  must be able to authenticate the transaction.
   o  must be able to update address records to support automated
      renumbering.
   o  must be able to update DS records to support DNSKEY rollover buy
      key management tools.
   o  must work for unsigned zones (parent and/or child).
   o  must work for signed zones (parent and/or child).
   o  must work for RRR managed zones.
   o  must work for non RRR managed zones.
   o  desirable support updating of NS RRsets so that nameservers can
      ensure delegations delgation data remains consistent.


3.  Translation

   The Registrar would host a server that authenticates UPDATE requests
   received directly or relayed by the Registry using TSIG [RFC2845],
   then translate the actions in the UPDATE request into EPP transaction
   requests.  The results of those EPP transactions would be relayed to
   the UPDATE client.

   Requests that are not TSIG signed or fail verification must be
   rejected.

   The translating server would handle a restricted subset of UPDATE
   requests, possibly ignoring the prerequiste section.  UPDATE requests
   would be limited to those supported by EPP.

   e.g.  Add NS record.  Delete all NS records.  Add A record.  Delete



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   AAAA record.  Add DS record.  Delete DS record.

   The translating server may also override/ignore the TTL in the UPDATE
   request.


4.  Authentication

   Authentication would be done using TSIG.  TSIG was designed to be
   used in a environment where requests are relayed.

   Authentication can be done down to the <NAME,TYPE> tuple.  There
   exist nameservers that already implement access contols down to this
   level of granularity based on the presented TSIG.

   This would allow nameservers to update their own address records as
   they get renumbered without being able to update anything else.

   This would allow DNSSEC key management software to update DS records
   without being able to update anything else.

   As Registrars do all the authentication and generate the signed
   responses there is no need for the Registry to have access to the
   private key material used in TSIG.

   Registrars already handle shared keys in these numbers with their web
   interfaces so it is not unreasonable to expect them to be able to
   handle a similar number of shared TSIG keys.


5.  Direct to Registrar

   The hardest part of Direct to Registrar is finding where to send the
   UPDATE request.  This would most probably just be advised to the
   Registrant.


6.  Indirect to Registrar

   In the indirect model the Registry would host a UPDATE relay server
   which would examine the first record of the UPDATE section and relay
   the request to the Registrar of record for the owner name of that
   record.  The Registrar would verify the validity if the request based
   on the TSIG then update the registry contents using EPP if
   appropriate.  The response from the Registrar would be relayed back
   to the client via the Registry.

   The Registry takes no action other than to relay the request and



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   response unless it is directed to do so by the Registrar.

   The relay can use either TCP or UDP when forwarding UPDATE requests
   as TSIG supports changes to the DNS id field when a request/response
   is relayed.  Only the Registrar and the client (Registrant) need to
   know the TSIG secret.

   This is consistent with how tools like nsupdate work out where to
   send a UPDATE request if the zone is not explicity set.  They look at
   the ownername of the first record and use it to discover the
   containing zone.


7.  UPDATE Server Discovery

   UPDATE server discovery is a issue when the RRR model is in use as
   the UPDATE may need to be directed through EPP and/or sent to a
   Registrar.  There are a number of way this could be done:

   1) Adding a underscore infix labels to the zone which contain SRV
   records at pointing to Registar/Registry servers for each child.

   e.g. <child>._update._tcp.<parent> SRV 0 0 53 server.example.tld

   The server pointed to could be be a relay server, as described above,
   or a UDPATE to EPP translating server.  A relay server would allow
   for slower zone growth.

   Using underscore infix labels requires no changes to nameservers
   operated by Registries but does require the zone content to be
   updated or a separate zone (e.g. _update._tcp.<parent>) to be
   delegated to contain this information.

   A level of indirection could be added by using CNAME records to point
   to a domain operated by the registrar which contains the SRV record.
   This would allow the registrar to update the SRV records without
   having to update the zone being served by the registry.  The CNAME
   would be updated on registrar changes.  Note the target name the
   CNAME could also be managed by the registry as a way to consolidate
   the SRV record management.

           child._update._tcp.tld CNAME registrar._registrars.tld
           registrar._registrars.tld SRV 0 0 53 server.example.tld

   As with traditional use of SRV, non-support can be signaled with

           *._update._tcp SRV 0 0 0 .




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   If the Resistry is operating a relay this can be supported with a
   single wildcard record.

           *._update._tcp SRV 0 0 0 server.registry.tld

   The client can fallback to direct update to parent servers if no SRV
   record is discovered.  This allows the scheme to work outside of the
   registry, registrar, registant model.

   2) Extend UDPATE to return the update server.  Currently the Zone
   section of the UPDATE refers to the zone to be update and is
   identified by the <QNAME,SOA,QCLASS> tuple.  Replacing SOA with one
   or more of DS, NS, A and AAAA would allow a nameserver to distingish
   between a traditional UPDATE request and a request to find the UPDATE
   servers.  The tuple would contain the resource to be updated and the
   reply would contain SRV records pointing to the UPDATE servers.  As
   there would possibly more than one parent the owner records would
   refer to the parent zone being updated.


8.  Security Considerations

   The UPDATE requests are all TSIG signed.  This is a proven method for
   securing UPDATE requests in the DNS.


9.  Normative References

   [RFC2136]  Vixie, P., Thomson, S., Rekhter, Y., and J. Bound,
              "Dynamic Updates in the Domain Name System (DNS UPDATE)",
              RFC 2136, April 1997.

   [RFC2845]  Vixie, P., Gudmundsson, O., Eastlake, D., and B.
              Wellington, "Secret Key Transaction Authentication for DNS
              (TSIG)", RFC 2845, May 2000.


Author's Address

   M. Andrews
   Internet Systems Consortium
   950 Charter Street
   Redwood City, CA  94063
   US

   Email: marka@isc.org





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