Network Working Group M. Andrews
Internet-Draft ISC
Expires: December 17, 2006 June 15, 2006
Locally-served Zones
draft-ietf-dnsop-default-local-zones-00
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Copyright (C) The Internet Society (2006).
Abstract
Practice has shown that there are a number of DNS zones all iterative
resolvers and recursive nameservers should, unless configured
otherwise, automatically serve. RFC 4193 already specifies that this
should occur for D.F.IP6.ARPA. This document extends the practice to
cover the IN-ADDR.ARPA zones for RFC 1918 address space and other
well known zones with similar usage constraints.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Reserved Words . . . . . . . . . . . . . . . . . . . . . . 3
2. Effects on sites using RFC 1918 addresses. . . . . . . . . . . 3
3. Changes Iterative Resolver Behaviour. . . . . . . . . . . . . 4
4. Lists Of Zones Covered . . . . . . . . . . . . . . . . . . . . 4
4.1. RFC 1918 Zones . . . . . . . . . . . . . . . . . . . . . . 4
4.2. RFC 3330 Zones . . . . . . . . . . . . . . . . . . . . . . 5
4.3. Local IPv6 Unicast Addresses . . . . . . . . . . . . . . . 5
4.4. IPv6 Locally Assigned Local Addresses . . . . . . . . . . 5
4.5. IPv6 Link Local Addresses . . . . . . . . . . . . . . . . 5
5. Zones that are Out-Of-Scope . . . . . . . . . . . . . . . . . 5
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
7. Security Considerations . . . . . . . . . . . . . . . . . . . 6
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 7
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 7
9.1. Normative References . . . . . . . . . . . . . . . . . . . 7
9.2. Informative References . . . . . . . . . . . . . . . . . . 7
Appendix A. Change History [To Be Removed on Publication] . . . . 8
A.1. draft-ietf-dnsop-default-local-zones-00.txt . . . . . . . 8
A.2. draft-andrews-full-service-resolvers-03.txt . . . . . . . 8
A.3. draft-andrews-full-service-resolvers-02.txt . . . . . . . 8
Appendix B. Proposed Status [To Be Removed on Publication] . . . 8
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 9
Intellectual Property and Copyright Statements . . . . . . . . . . 10
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1. Introduction
Practice has shown that there are a number of DNS [RFC 1034] [RFC
1035] zones all iterative resolvers and recursive nameservers 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 [RFC 1918] and the IP6.ARPA zones for
locally assigned local IPv6 addresses, [RFC 4193].
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
the zones below.
[RFC 4193] 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 [RFC 1918] 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 [RFC
1918] 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 [RFC 2119].
2. Effects on sites using RFC 1918 addresses.
Sites using [RFC 1918] addresses should already be serving these
queries internally, without referring them to public name servers on
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the Internet.
The main impact will be felt on sites that make use of recursion for
reverse lookups for [RFC 1918] 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 [RFC 1918] 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 Iterative Resolver Behaviour.
Unless configured otherwise, a iterative resolver will return name
errors for queries within the lists 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.
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.
@ 10800 IN SOA @ . 1 3600 1200 604800 10800
@ 10800 IN NS @
4. Lists Of Zones Covered
The lists below are expected to seed a IANA registry.
4.1. RFC 1918 Zones
10.IN-ADDR.ARPA
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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. RFC 3330 Zones
0.IN-ADDR.ARPA /* IPv4 "THIS" NETWORK */
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 Unicast 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.IP
6.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.IP
6.ARPA
4.4. IPv6 Locally Assigned Local Addresses
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. Zones that are Out-Of-Scope
IPv6 site-local addresses and IPv6 Globally Assigned Local addresses
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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 however, 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.
6. 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.
This registry can be amended through IESG reviewed RFC publication.
7. Security Considerations
During the initial deployment phase, particularly where [RFC 1918]
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
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them using DNSSEC [RFC 4035] by publishing and using DNSSEC trust
anchors. 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.
8. Acknowledgements
This work was supported by the US National Science Foundation
(research grant SCI-0427144) and DNS-OARC.
9. References
9.1. Normative References
[RFC 1034]
Mockapetris, P., "DOMAIN NAMES - CONCEPTS AND FACILITIES",
RFC 1034, STD 13, November 1987.
[RFC 1035]
Mockapetris, P., "DOMAIN NAMES - IMPLEMENTATION AND
SPECIFICATION", RFC 1035, STD 13, November 1987.
[RFC 1918]
Rekhter, Y., Moskowitz, B., Karrenberg, D., de Groot, G.,
and E. Lear, "Address Allocation for Private Internets",
RFC 1918, February 1996.
[RFC 2119]
Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC 4035]
Arends, R., Austein, R., Larson, M., Massey, D., and S.
Rose, "Protocol Modifications for the DNS Security
Extensions", RFC 4035, March 2005.
9.2. Informative References
[AS112] "AS112 Project", <http://as112.net/>.
[RFC 4193]
Hinden, R. and B. Haberman, "Unique Local IPv6 Unicast
Addresses", RFC 4193, October 2005.
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Appendix A. Change History [To Be Removed on Publication]
A.1. draft-ietf-dnsop-default-local-zones-00.txt
Adopted by DNSOP.
"Author's Note" re-titled "Zones that are Out-Of-Scope"
Add note that these zone are expected to seed the IANA registry.
Title changed.
A.2. draft-andrews-full-service-resolvers-03.txt
Added "Proposed Status".
A.3. draft-andrews-full-service-resolvers-02.txt
Added 0.IN-ADDR.ARPA.
Appendix B. Proposed Status [To Be Removed on Publication]
This Internet-Draft is being submitted for eventual publication as an
RFC with a proposed status of Best Current Practice.
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Author's Address
Mark P. Andrews
Internet Systems Consortium
950 Charter Street
Redwood City, CA 94063
US
Email: Mark_Andrews@isc.org
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