Network Working Group M. Andrews Internet-Draft ISC Expires: May 8, 2014 November 4, 2013 Updating Parent Zones draft-andrews-dnsop-update-parent-zones-02 Abstract DNS UPDATE was developed to allow DNS zones to be updated. There is a perception that UPDATE can not 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 Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on May 8, 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 Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Andrews Expires May 8, 2014 [Page 1] Internet-Draft Updating Parent Zones November 2013 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Translation . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Authentication . . . . . . . . . . . . . . . . . . . . . . . . 3 4. Direct to Registrar . . . . . . . . . . . . . . . . . . . . . . 4 5. Indirect to Registrar . . . . . . . . . . . . . . . . . . . . . 4 6. UPDATE Server Discovery . . . . . . . . . . . . . . . . . . . . 4 7. Security Considerations . . . . . . . . . . . . . . . . . . . . 5 8. Normative References . . . . . . . . . . . . . . . . . . . . . 5 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 6 Andrews Expires May 8, 2014 [Page 2] Internet-Draft Updating Parent Zones November 2013 1. Introduction UPDATE [RFC2136]is designed to update any zone in the DNS. This includes updating delegating NS records, glue address records and DS record. 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 heirachy. 2. 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 are 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 AAAA record. Add DS record. Delete DS record. The translating server may also override/ignore the TTL in the UPDATE request. 3. 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 tuple. There exist nameservers that already implement access contols down to this level of granuality 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 Andrews Expires May 8, 2014 [Page 3] Internet-Draft Updating Parent Zones November 2013 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 material using in TSIG. Registrars already handle shared keys in these numbers with their web interfaces. 4. 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. 5. 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 response would be relayed back. 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. This is consistent with how tools like nsupdate work out where to send a UPDATE request. They look at the ownername of the first record and use it to discover the containing zone. 6. 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 a sent to a Registrar. There are a number of way this could be done. Adding a underscore infix labels to the zone which contain SRV records at pointing to Registar/Registry servers for each child. e.g. ._update._tcp. SRV 0 0 53 server.example.tld The servers pointed 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 Andrews Expires May 8, 2014 [Page 4] Internet-Draft Updating Parent Zones November 2013 updated or a separate zone (e.g. _update._tcp.) 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. As with traditional use of SRV non-support can be signaled with "*._update._tcp SRV 0 0 0 ." 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. child._update._tcp.tld CNAME registrar._registrars.tld registrar._registrars.tld SRV 0 0 53 server.example.tld 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 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. One could use a new OPCODE for UPDATE server discovery. 7. Security Considerations The UPDATE requests are all TSIG signed. This is a proven method for securing UPDATE requests in the DNS. 8. 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 Andrews Expires May 8, 2014 [Page 5] Internet-Draft Updating Parent Zones November 2013 (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 Andrews Expires May 8, 2014 [Page 6]