One document matched: draft-ietf-dnsop-default-local-zones-02.txt
Differences from draft-ietf-dnsop-default-local-zones-01.txt
Network Working Group M. Andrews
Internet-Draft ISC
Intended status: Best Current June 8, 2007
Practice
Expires: December 10, 2007
Locally-served DNS Zones
draft-ietf-dnsop-default-local-zones-02
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Copyright Notice
Copyright (C) The IETF Trust (2007).
Abstract
Experience has shown that there are a number of DNS zones all
iterative resolvers and recursive nameservers should, unless
configured otherwise, automatically serve. RFC 4193 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 characteristics.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Reserved Words . . . . . . . . . . . . . . . . . . . . . . 3
2. Effects on sites using RFC 1918 addresses. . . . . . . . . . . 4
3. Changes to Iterative Resolver Behaviour. . . . . . . . . . . . 4
4. Lists Of Zones Covered . . . . . . . . . . . . . . . . . . . . 5
4.1. RFC 1918 Zones . . . . . . . . . . . . . . . . . . . . . . 5
4.2. RFC 3330 Zones . . . . . . . . . . . . . . . . . . . . . . 5
4.3. Local IPv6 Unicast Addresses . . . . . . . . . . . . . . . 6
4.4. IPv6 Locally Assigned Local Addresses . . . . . . . . . . 6
4.5. IPv6 Link Local Addresses . . . . . . . . . . . . . . . . 6
5. Zones that are Out-Of-Scope . . . . . . . . . . . . . . . . . 6
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
7. Security Considerations . . . . . . . . . . . . . . . . . . . 7
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 7
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 8
9.1. Normative References . . . . . . . . . . . . . . . . . . . 8
9.2. Informative References . . . . . . . . . . . . . . . . . . 9
Appendix A. Change History [To Be Removed on Publication] . . . . 9
A.1. draft-ietf-dnsop-default-local-zones-02.txt . . . . . . . 9
A.2. draft-ietf-dnsop-default-local-zones-01.txt . . . . . . . 9
A.3. draft-ietf-dnsop-default-local-zones-00.txt . . . . . . . 9
A.4. draft-andrews-full-service-resolvers-03.txt . . . . . . . 9
A.5. draft-andrews-full-service-resolvers-02.txt . . . . . . . 9
Appendix B. Proposed Status [To Be Removed on Publication] . . . 9
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 10
Intellectual Property and Copyright Statements . . . . . . . . . . 11
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1. Introduction
Experience has shown that there are a number of DNS [RFC 1034] [RFC
1035] zones that all iterative resolvers and recursive nameservers
SHOULD, unless intentionally 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 unique 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 it has therefore become
necessary to deploy sacrificial name servers to 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 for these name spaces but drop the
responses put 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 listed in Section 4.
[RFC 4193] 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 public
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.
This recommendation should also help DNS responsiveness for sites
which are using [RFC 1918] addresses but do not follow the last
paragraph in Section 3 of [RFC 1918].
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].
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2. Effects on sites using RFC 1918 addresses.
For most sites using [RFC 1918] addresses, the changes here will have
little or no detrimental effect. If the site does not already have
the reverse tree populated the only effect will be that the name
error responses will be generated locally rather than remotely.
For sites that do have the reverse tree populated, most will either
have a local copy of the zones or will be forwarding the queries to
servers which have local copies of the zone. Therefore this
recommendation will not be relevant.
The most significant impact will be felt at sites that make use of
delegations for [RFC 1918] addresses and have populated these zones.
These sites will need to override the default configuration expressed
in this document to allow resolution to continue. Typically, such
sites will be fully disconnected from the Internet and have their own
root servers for their own non-Internet DNS tree.
3. Changes to Iterative Resolver Behaviour.
Unless configured otherwise, an iterative resolver will now return
name errors (RCODE=3) for queries within the zones in Section 4, with
the obvious exception of queries for the zone name itself where SOA,
NS and "no data" responses will be returned as appropriate to the
query type. One common way to do this is to serve empty (SOA and NS
only) zones.
An implementation of this recommendation MUST provide a mechanism to
disable this new behaviour, and SHOULD do so 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 to the public Internet servers. This document
recommends that the NS record defaults to the name of the zone and
the SOA MNAME defaults to the name of the only NS RR's target. The
SOA RNAME should default to "nobody.invalid." [RFC 2606].
Implementations SHOULD provide a mechanism to set these values. No
address records need to be provided for the name server.
Below is an example of a generic empty zone in master file format.
It will produce a negative cache TTL of 3 hours.
@ 10800 IN SOA @ nobody.invalid. 1 3600 1200 604800 10800
@ 10800 IN NS @
The SOA RR is needed to support negative caching [RFC 2308] of name
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error responses and to point clients to the primary master for DNS
dynamic updates.
SOA values of particular importance are the MNAME, the SOA RR's TTL
and the negTTL value. Both TTL values SHOULD match. The rest of the
SOA timer values MAY be chosen arbitrarily since it they are not
intended to control any zone transfer activity.
The NS RR is needed as some UPDATE clients use NS queries to discover
the zone to be updated. Having no address records for the name
server should abort UPDATE processing in the client.
4. Lists Of Zones Covered
4.1. RFC 1918 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. RFC 3330 Zones
See [RFC 3330].
+------------------------------+------------------------------+
| Zone | Description |
+------------------------------+------------------------------+
| 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 */ |
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| 255.255.255.255.IN-ADDR.ARPA | /* IPv4 BROADCAST */ |
+------------------------------+------------------------------+
4.3. Local IPv6 Unicast Addresses
See [RFC 4291], Sections 2.4, 2.5.2 and 2.5.3.
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
See [RFC 4193].
D.F.IP6.ARPA
4.5. IPv6 Link Local Addresses
See [RFC 4291], Sections 2.4 and 2.5.6.
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, [RFC 4291] Sections 2.4 and 2.57, and IPv6
Centrally Assigned Local [RFC 4193] 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.
However, sacrificial servers for C.E.F.IP6.ARPA through
F.E.F.IP6.ARPA may still need to be deployed in the short term if the
traffic becomes excessive.
For IPv6 Centrally Assigned Local addresses (L = 0) [RFC 4193], 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 in Section 4.4. If they do, then
registries will need to take steps to ensure that name servers are
provided for these addresses.
This document also ignores IP6.INT. IP6.INT has been wound up with
only legacy resolvers now generating reverse queries under IP6.INT.
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This document has also deliberately ignored names immediately under
the root. While there is a subset of queries to the roots which
could be addressed using the techniques described here (e.g. .local,
.workgroup and IPv4 addresses), there is also a vast amount of
traffic that requires a different strategy (e.g. lookups for
unqualified hostnames, IPv6 addresses).
6. IANA Considerations
This document requests that IANA establish a registry of zones which
require this default behaviour. The initial contents of which are in
Section 4. Implementors are encouraged to check this registry and
adjust their implementations to reflect changes therein.
This registry can be amended through "IETF Consensus" as per [RFC
2434] or IETF Review in 2434bis.
ICANN should co-ordinate with the RIRs to ensure that DNSSEC
deployment in the reverse trees that these zone are delegated from
happens in the manner described in Section 7.
7. Security Considerations
During the initial deployment phase, particularly where [RFC 1918]
addresses are in use, there may be some clients that unexpectedly
receive a name error rather than a PTR record. This may cause some
service disruption until full service resolvers have been re-
configured.
As 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 [RFC 4035] by publishing and using DNSSEC trust
anchors. This will protect the clients from accidental leakage of
unsigned answers from the Internet.
8. Acknowledgements
This work was supported by the US National Science Foundation
(research grant SCI-0427144) and DNS-OARC.
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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 2308]
Andrews, M., "Negative Caching of DNS Queries (DNS
NCACHE)", RFC 2398, March 1998.
[RFC 2434]
Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 2434,
October 1998.
[RFC 2606]
Eastlake, D. and A. Panitz, "Reserved Top Level DNS
Names", BCP 32, RFC 2606, June 1999.
[RFC 4035]
Arends, R., Austein, R., Larson, M., Massey, D., and S.
Rose, "Protocol Modifications for the DNS Security
Extensions", RFC 4035, March 2005.
[RFC 4193]
Hinden, R. and B. Haberman, "Unique Local IPv6 Unicast
Addresses", RFC 4193, October 2005.
[RFC 4291]
Hinden, R. and S. Deering, "IP Version 6 Addressing
Architecture", RFC 4291, February 2006.
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9.2. Informative References
[AS112] "AS112 Project", <http://as112.net/>.
[RFC 3330]
"Special-Use IPv4 Addresses", RFC 3330, September 2002.
Appendix A. Change History [To Be Removed on Publication]
A.1. draft-ietf-dnsop-default-local-zones-02.txt
RNAME now "nobody.invalid."
Revised language.
A.2. draft-ietf-dnsop-default-local-zones-01.txt
Revised impact description.
Updated to reflect change in IP6.INT status.
A.3. 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.4. draft-andrews-full-service-resolvers-03.txt
Added "Proposed Status".
A.5. 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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