M. Andrews Internet-Draft Internet Systems Consortium Expires: March 21, 2006 September 2005 Configuration Issues Facing Full Service DNS Resolvers In The Presence of Private Network Addressing draft-andrews-full-service-resolvers-00.txt Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. 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." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on February 19, 2006. Copyright Notice Copyright (C) The Internet Society (2005). Abstract Practice has shown that there are a number of zones all full service resolvers should, unless configured otherwise, automatically serve. [draft-ietf-ipv6-unique-local-addr] already specifies that this should occur for D.F.IP6.ARPA. This document extends the practice to cover the IN-ADDR.ARPA zones for RFC1918 address space and other well known zones with similar usage constraints. Andrews [Page 1] RFC DRAFT August 2005 Table of Contents. 1. Introduction 1.1. Reserved Words 2. Effects on sites using RFC1918 addresses. 3. Changes To Full Service Resolver Behaviour. 4. List Of Zones Covered. 4.1. RFC1918 Zones 4.2. RFC3330 Zones 4.3. Local IPv6 Uni-cast Addresses 4.4. IPv6 Locally Assigned Local Address 4.5. IPv6 Link Local Addresses 5. Author's Note 6. Acknowledgements IANA Considerations Security Considerations References Normative References Informative References Author's Address Intellectual Property Statement Disclaimer of Validity Copyright Statement Acknowledgement 1. Introduction Practice has shown that there are a number of zones all full service resolvers should, unless configured otherwise, automatically serve. These zones include, but are not limited to, the IN-ADDR.ARPA zones for the address space allocated by [RFC1918] and the IP6.ARPA zones for locally assigned local IPv6 addresses, [draft-ietf-ipv6-unique- local-addr]. This recommendation is made because data has shown that significant leakage of queries for these name spaces is occurring, despite instructions to restrict them, and because sacrificial name servers have been deployed to protect the immediate parent name servers for these zones from excessive, unintentional, query load [AS112]. There is every expectation that the query load will continue to increase unless steps are taken as outlined here. Additionally, queries from clients behind badly configured firewalls that allow outgoing queries but drop responses for these name spaces also puts a significant load on the root servers. They also cause operational load for the root server operators as they have to reply to queries about why the root servers are "attacking" these clients. Changing the default configuration will address all these issues for Andrews [Page 2] RFC DRAFT August 2005 the zones below. [draft-ietf-ipv6-unique-local-addr] already recommends that queries for D.F.IP6.ARPA be handled locally. This document extends the recommendation to cover the IN-ADDR.ARPA zones for [RFC1918] and other well known IN-ADDR.ARPA and IP6.ARPA zones for which queries should not appear on the Internet. It is hoped that by doing this the number of sacrificial servers [AS112] will not have to be increased and may in time be reduced. It should also help DNS responsiveness for sites which are using [RFC1918] addresses but are misconfigured. 1.1. Reserved Words The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119]. 2. Effects on sites using RFC1918 addresses. Sites using [RFC1918] addresses should already be serving these queries internally, without referring them to public name servers on the Internet. The main impact will be felt on sites that make use of recursion for reverse lookups for [RFC1918] addresses and have populated these zones. Typically, such sites will be fully disconnected from the Internet and have their own root servers for their own non-Internet DNS tree or make use of local delegation overrides (otherwise known as "forwarding") to reach the private servers for these reverse zones. These sites will need to override the default configuration proposed in this draft to allow resolution to continue. Other sites that use [RFC1918] addresses and either have local copies of the reverse zones or don't have reverse zones configured should see no difference other than the name error appearing to come from a different source. 3. Changes To Full Service Resolver Behaviour. Unless configured otherwise, a full service resolver will return name errors for queries within the list of zones covered below. One common way to do this is to serve empty (SOA and NS only) zones. A server doing this MUST provide a mechanism to disable this behaviour, preferably on a zone by zone basis. Andrews [Page 3] RFC DRAFT August 2005 If using empty zones one should not use the same NS and SOA records as used on the public Internet servers as that will make it harder to detect leakage from the public Internet servers. This document recommends that the NS record default to the name of the zone and the SOA MNAME default to the name of the zone. The SOA RNAME should default to ".". Implementations SHOULD provide a mechanism to set these values. No address records need to be provided for the name server. e.g. @ 10800 IN SOA @ . 1 3600 1200 604800 10800 @ 10800 IN NS @ 4. List Of Zones Covered. 4.1. RFC1918 Zones 10.IN-ADDR.ARPA 16.172.IN-ADDR.ARPA 17.172.IN-ADDR.ARPA 18.172.IN-ADDR.ARPA 19.172.IN-ADDR.ARPA 20.172.IN-ADDR.ARPA 21.172.IN-ADDR.ARPA 22.172.IN-ADDR.ARPA 23.172.IN-ADDR.ARPA 24.172.IN-ADDR.ARPA 25.172.IN-ADDR.ARPA 26.172.IN-ADDR.ARPA 27.172.IN-ADDR.ARPA 28.172.IN-ADDR.ARPA 29.172.IN-ADDR.ARPA 30.172.IN-ADDR.ARPA 31.172.IN-ADDR.ARPA 168.192.IN-ADDR.ARPA 4.2. RFC3330 Zones 127.IN-ADDR.ARPA /* IPv4 LOOP-BACK NETWORK */ 254.169.IN-ADDR.ARPA /* IPv4 LINK LOCAL */ 2.0.192.IN-ADDR.ARPA /* IPv4 TEST NET */ 255.255.255.255.IN-ADDR.ARPA /* IPv4 BROADCAST */ 4.3. Local IPv6 Uni-cast Addresses 0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.\ IP6.ARPA 1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.\ Andrews [Page 4] RFC DRAFT August 2005 IP6.ARPA 4.4. IPv6 Locally Assigned Local Address D.F.IP6.ARPA 4.5. IPv6 Link Local Addresses 8.E.F.IP6.ARPA 9.E.F.IP6.ARPA A.E.F.IP6.ARPA B.E.F.IP6.ARPA 5. Author's Note: IPv6 site-local addresses and IPv6 Globally Assigned Local addresses are not covered here. It is expected that IPv6 site-local addresses will be self correcting as IPv6 implementations remove support for site-local addresses howsever, sacrificial servers for C.E.F.IP6.ARPA to F.E.F.IP6.ARPA may still need to be deployed in the short term if the traffic becomes excessive. For IPv6 Globally Assigned Local addresses there has been no decision made about whether the registries will provide delegations in this space or not. If they don't then C.F.IP6.ARPA will need to be added to the list above. If they do then registries will need to take steps to ensure that name servers are provided for these addresses. This document is also ignoring the IP6.INT counterpart for the IP6.ARPA addresses above. IP6.INT is in the process of being wound up with clients already not querying for this suffix. This document has also deliberately ignored zones immediately under the root. The author believes other methods would be more applicable for dealing with the excess / bogus traffic these generate. IANA Considerations This document recommends that IANA establish a registry of zones which require this default behaviour, the initial contents are above. More zones are expected to be added, and possibly deleted from this registry over time. Name server implementors are encouraged to check this registry and adjust their implementations to reflect changes therein. Security Considerations During the initial deployment phase, particularly where [RFC1918] Andrews [Page 5] RFC DRAFT August 2005 addresses are in use, there may be some clients that unexpectedly receive name error rather than a PTR record. This may cause some service disruption until full service resolvers have been re- configured. When DNSSEC is deployed within the IN-ADDR.ARPA and IP6.ARPA namespaces, the zones listed above will need to be delegated as insecure delegations. This will allow DNSSEC validation to succeed for queries in these spaces despite not being answered from the delegated servers. It is recommended that sites actively using these namespaces secure them using DNSSEC. This is good just on general principles. It will also protect the clients from accidental leakage of answers from the Internet which will be unsigned. 6. Acknowledgements This work was supported by the US National Science Foundation (research grant SCI-0427144) and DNS-OARC. References Normative References [RFC1918] Rekhter, Y., Moskowitz, B., Karrenberg, D., de Groot, G. J., Lear, E., "Address Allocation for Private Internets", RFC 1918, February 1996. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. Informative References [draft-ietf-ipv6-unique-local-addr] Hinden, R., Haberman, B., "Unique Local IPv6 Unicast Addresses", draft-ietf-ipv6-unique-local-addr-09.txt, work-in-progress, January 2005. [AS112] AS112 Project, . Author's Address: Mark Andrews Internet Systems Consortium 950 Charter St. Redwood City, CA 94063 US Andrews [Page 6] RFC DRAFT August 2005 Email: Mark_Andrews@isc.org Intellectual Property Statement The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. 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Disclaimer of Validity This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Copyright Statement Copyright (C) The Internet Society (2005). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. Acknowledgement Funding for the RFC Editor function is currently provided by the Internet Society. Andrews [Page 7]