Internet DRAFT - draft-wkumari-dnsop-omniscient-as112
draft-wkumari-dnsop-omniscient-as112
Network Working Group W. Kumari
Internet-Draft Google
Updates: 6304 (if approved) W. Sotomayor
Intended status: Informational NRC-CNRC
Expires: December 23, 2013 J. Abley
ICANN
R. Bellis
Nominet UK
June 21, 2013
Omniscient AS112 Servers
draft-wkumari-dnsop-omniscient-as112-03
Abstract
The AS112 Project loosely coordinates Domain Name System (DNS)
servers to which DNS zones corresponding to private use addresses are
delegated. Queries for names within those zones have no useful
responses in a global context. The purpose of this project is to
reduce the load of such junk queries on the authoritative name
servers that would otherwise receive them, and instead direct the
load to name servers operated within the AS112 project.
Due to the loosely-coordinated nature of the project, adding and
dropping zones from the AS112 servers is difficult. This document
proposes a mechanism by which AS112 name servers could answer
authoritatively for all possible zones. This eliminates the add/drop
problem, changing it to a matter of delegation within the DNS and
requiring no operational changes on the servers themselves.
This document updates RFC 6304.
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
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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
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
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This Internet-Draft will expire on December 23, 2013.
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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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3.1. DNSSEC . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Protocol Considerations . . . . . . . . . . . . . . . . . . . 4
5. Operational Considerations . . . . . . . . . . . . . . . . . 6
6. Addressing Considerations . . . . . . . . . . . . . . . . . . 7
7. Updates to RFC 6304 . . . . . . . . . . . . . . . . . . . . . 7
7.1. Changes to Section 3.4, Routing Software . . . . . . . . 7
7.2. Changes to Section 3.5, DNS Software . . . . . . . . . . 8
7.3. Changes to Section 3.6, Testing a Newly Installed Node . 9
8. Other Approaches . . . . . . . . . . . . . . . . . . . . . . 9
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
10. Security Considerations . . . . . . . . . . . . . . . . . . . 10
11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 10
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 10
12.1. Normative References . . . . . . . . . . . . . . . . . . 10
12.2. Informative References . . . . . . . . . . . . . . . . . 11
Appendix A. Implementation / "Running Code" . . . . . . . . . . 11
Appendix B. Document Notes . . . . . . . . . . . . . . . . . . . 11
B.1. Venue . . . . . . . . . . . . . . . . . . . . . . . . . . 11
B.2. Textual Substitutions . . . . . . . . . . . . . . . . . . 11
B.3. Open Questions . . . . . . . . . . . . . . . . . . . . . 11
B.4. Change History . . . . . . . . . . . . . . . . . . . . . 12
B.4.1. draft-wkumari-dnsop-omniscient-as112-00 . . . . . . . 13
B.4.2. draft-wkumari-omniscient-as112-00 . . . . . . . . . . 14
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 14
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1. Introduction
The AS112 Project loosely coordinates Domain Name System (DNS)
servers [RFC1034] to which DNS zones corresponding to private use
addresses are delegated. Queries for names within those zones have
no useful responses in a global context. The purpose of the project
is to reduce the load of such junk queries on the authoritative name
servers that would otherwise receive them, directing the load instead
to name servers operated within the AS112 project.
To date, AS112 nameservers have been used exclusively for names
corresponding to the reverse mapping for private-use IPv4 addresses.
A description of current advice for AS112 operators, including
motivations and guidance for technical deployment and operations can
be found in [RFC6304].
Other DNS domains have analogously local significance. Examples
corresponding to the reverse-mapping of special-use IPv4 and IPv6
addresses can be found in [RFC6303].
It is to be expected that new domains will be identified from time to
time that fit the use pattern for which delegation to AS112 servers
might be desirable. There is currently no mechanism by which
particular zones can be reliably added to or dropped from AS112
servers, however. This is principally a consequence of the loosely-
coordinated nature of the project, coupled with a desire to avoid
lame delegations which might have unforeseen operational
consequences.
This document proposes a mechanism by which AS112 servers could
provide consistent, reliable negative responses for all DNS queries,
eliminating the operational requirement to add or drop particular
zones from all AS112 servers.
2. Terminology
An "Existing AS112 Server" is a DNS name server configured according
to the guidance provided in [RFC6304] and listening on the IPv4
addresses 192.175.48.1 (PRISONER.IANA.ORG), 192.175.48.6
(BLACKHOLE-1.IANA.ORG) and 192.175.48.42 (BLACKHOLE-2.IANA.ORG).
An "Omniscient AS112 Server" is a DNS nameserver configured according
to the guidance provided in [RFC6304], as extended by this document.
Such servers listen on the same addresses as Existing AS112 Servers,
but also additional addresses as described in Section 6.
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Where discussions apply equally to Existing AS112 Servers and
Omniscient AS112 Servers, the unqualified phrase "AS112 Server" is
used.
An "AS112 Zone" is a DNS zone which has been delegated to an AS112
Server.
An "Existing AS112 Zone" is an AS112 Zone which has been delegated to
an existing AS112 Server.
3. Overview
An Omniscient AS112 Server is one that acts as though it is
authorative for all zones, but denies that there is any data. This
allows domains to be delegated to it and to receive back an
authorative NoError / NoData response for queries for labels in that
domain. This allows new zones to be added to or removed from the
AS112 project by simply delegating to the Omniscient AS112 servers
without needing to co-ordinate with the server operators.
It is worth noting that the term Omniscient is imperfect - it makes
it sound like an Omniscient AS112 Server knows the answers to
everything, whereas all it actually knows that it doesn't know
anything. A thesaurus shows that a good antonym for "Omniscient" is
"stupid", but we are not using this as we feel that it is too broad a
term and covers most nameservers. (:-))
3.1. DNSSEC
Responses from Omniscient AS112 servers (like Existing AS112 servers)
are not DNSSEC signed. This does not cause issues as responses have
no meaning in the global context, and so the delegations to these are
either not signed or are insecure delegations.
4. Protocol Considerations
Familiarity with [RFC1034] and [RFC1035] is assumed.
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In order to safely cache the response, DNS implementations require
the closest-enclosing SOA to be returned. An Omniscient AS112 server
(which is not configured with a specific list of zones, and hence
zone cuts) cannot necessarily know where that is. Removing labels
and guessing (whether to the extreme case of removing all labels, or
returning one, or anything in between) cannot be guaranteed to be
appropriate, since the answers might clash with authentic answers
already present in client caches. A client that has followed a
referral to an Omniscient AS112 server is guaranteed not to have a
cached SOA that matches the QNAME, however, so Omniscient AS112
servers use the QNAME as the SOA and owner name.
Please see Appendix A for information on an implementation ("running
code") that does this.
AS112 Servers respond to AXFR (QTYPE=252) or IXFR (QTYPE=251) with
RCODE=REFUSED.
A TYPE=6 (SOA) resource record for Omniscient AS112 servers contains:
o MNAME = "a.as112.net."
o RNAME = "hostmaster.as112.net."
o SERIAL = 1
o REFRESH =604800 (7 days)
o RETRY = 2592000 (30 days)
o EXPIRE = 604800 (7 days)
o MINIMUM = 604800 (7 days, negative caching TTL)
For all queries with QTYPE=2 (NS) an AS112 Server responds with an
authoritative (AA=1) answer with NoError (RCODE=0), the owner name
copied from the QNAME and two resource records of TYPE=2 (NS), one
containing "B.AS112.NET." and the containing "C.AS112.NET.".
For all queries with QTYPE=6 (SOA) an AS112 Server responds with an
authoritative (AA=1) answer with NoError (RCODE=0), the owner name
copied from the QNAME and one (ANCOUNT=1) resource record of TYPE=6
(SOA).
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For all queries with QTYPE=255 (*, also known as ANY) an AS112 Server
responds with an authoritative (AA=1) answer with NoError (RCODE=0)
the owner name copied from the QNAME and three (ANCOUNT=3) resource
records, one containing the SOA (as described above), and two
containing NS (also as described above).
For all other queries an AS112 Server responds with an authoritative
(AA=1) NoError (RCODE=0) with the owner name copied from the QNAME in
the request and no answers (ANCOUNT=0). The resource record of
TYPE=6 (SOA) (as described above) should be returned in the authority
section. The presence of the SOA is to allow the negative cache TTL
to be set(see [RFC2308]).
5. Operational Considerations
Existing AS112 Servers address the protocol considerations described
in Section 4 by serving each existing AS112 Zone explicitly. In each
case the zone contents are identical, containing only required apex
SOA and NS records. Adding or dropping a delegation for an Existing
AS112 Zone requires coordination amongst all deployed Existing AS112
Server operators.
There is no practical expectation that AS112 Server operators
coordinate the configuration of their infrastructure or even make
their existence known in any systematic way. Delegation of new zones
to Existing AS112 Servers is hence problematic; there is an
expectation that such delegations would be lame for a significant
client population. Since the predictable behaviour of AS112 Servers
from clients is desirable, and it is possible that significant
variation would have operational consequences, no new zones should be
delegated to existing AS112 Servers.
Omniscient AS112 Servers generate a response (as described in
Section4 (Section 4)) as though they are authoritative for everything
("."). Adding or dropping a delegation for an AS112 Zone therefore
imposes no operational requirements on Omniscient AS112 Server
operators.
Delegation of new AS112 Zones should only be made to Omniscient AS112
Servers. Omniscient AS112 Servers, therefore, must listen on
additional addresses to those used by existing AS112 Servers.
Addressing is discussed in Section 6.
By ensuring that Omniscient AS112 Servers listen on Existing AS112
Servers' addresses as well as the new addresses specified in
Section 6 a smooth migration is possible, allowing Existing AS112
Servers to be reconfigured as Omniscient AS112 Servers. Omniscient
AS112 Servers are therefore a superset of AS112 Servers.
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6. Addressing Considerations
Omniscient AS112 Servers listen on the following addresses:
o IPv4-TBA1 (A.AS112.NET)
o IPv6-TBA1 (A.AS112.NET)
o IPv4-TBA2 (B.AS112.NET)
o IPv6-TBA2 (B.AS112.NET)
o IPv4-TBA3 (C.AS112.NET)
o IPv6-TBA3 (C.AS112.NET)
IPv4-TBA1, IPv4-TBA2 and IPv4-TBA3 are covered by a single IPv4
prefix, IPv4-PREFIX-TBA. Similarly, IPv6-TBA1, IPv6-TBA2 and
IPv6-TBA3 are covered by a single IPv6 prefix, IPv6-PREFIX-TBA.
The addresses specified for Omniscient AS112 Servers are deliberately
different from those assigned to Existing AS112 Servers for reasons
discussed in Section 5.
7. Updates to RFC 6304
7.1. Changes to Section 3.4, Routing Software
Omniscient AS112 Nodes with IPv4 connectivity should originate the
IPv4 service prefix associated with Existing AS112 Nodes,
192.175.48.0/24, and also the IPv4 service prefix associated with
Omniscient AS112 Nodes, IPv4-PREFIX-TBA.
Omniscient AS112 Nodes with IPv6 connectivity should originate the
IPv6 service prefix IPv6-PREFIX-TBA.
Applying this direction to the "bgpd.conf" file included as an
example in this section results in the configuration shown in Figure
1.
! bgpd.conf
!
hostname as112-bgpd
password <something>
enable password <supersomething>
!
! Note that all AS112 nodes use the local Autonomous System
! Number 112, and originate IPv4 and IPv6 prefixes (where IPv4
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! and IPv6 connectivity is available) as follows:
!
! IPv4: 192.175.48.0/24
! IPv4-PREFIX-TBA
!
! IPv6: IPv6-PREFIX-TBA
!
! All other addresses shown below are illustrative, and
! actual numbers will depend on local circumstances.
!
router bgp 112
bgp router-id 203.0.113.1
!
address-family ipv4
network 192.175.48.0
neighbor 192.0.2.1 remote-as 64496
neighbor 192.0.2.1 next-hop-self
neighbor 192.0.2.1 prefix-list AS112-v4 out
neighbor 192.0.2.1 filter-list 1 out
neighbor 192.0.2.2 remote-as 64497
neighbor 192.0.2.2 next-hop-self
neighbor 192.0.2.2 prefix-list AS112-v4 out
neighbor 192.0.2.2 filter-list 1 out
network 192.175.48.0/24
network IPv4-PREFIX-TBA
!
address-family ipv6 unicast
neighbor 2001:db8::1 remote-as 64496
neighbor 2001:db8::1 next-hop-self
neighbor 2001:db8::1 prefix-list AS112-v6 out
neighbor 2001:db8::1 filter-list 1 out
neighbor 2001:db8::2 remote-as 64497
neighbor 2001:db8::2 next-hop-self
neighbor 2001:db8::2 prefix-list AS112-v6 out
neighbor 2001:db8::2 filter-list 1 out
network IPv6-PREFIX-TBA
!
ip prefix-list AS112-v4 permit 192.175.48.0/24
ip prefix-list AS112-v4 permit IPv4-PREFIX-TBA
!
ipv6 prefix-list AS112-v6 permit IPv6-PREFIX-TBA
!
ip as-path access-list 1 permit ^$
Figure 1
7.2. Changes to Section 3.5, DNS Software
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Omniscient AS112 Servers should be configured to listen on the
addresses IPv6-TBA1, IPv6-TBA, IPv6-TBA3, IPv4-TBA1, IPv4-TBA2 and
IPv4-TBA3 in addition to the addresses used for Existing AS112
Servers.
Omniscient AS112 Servers generate an answer as described in Section 4
instead of explicitly serving the zones specified in [RFC6304].
As ISC BIND [BIND] does not provide the required functionality a
custom nameserver implementation needs to be deployed, and so the
example "named.conf" file in this section can be disregarded.
7.3. Changes to Section 3.6, Testing a Newly Installed Node
Testing should include all configured service addresses for an
Omniscient AS112 Server (IPv4 or IPv6 or both, as appropriate). Note
that the IPv4 service addresses include those described in [RFC6304]
for Existing AS112 Servers.
8. Other Approaches
[Editors note: This is provided for information only. We may want to
remove this before publication... or not. If we don't, we should
tidy it up, it is conversational at the moment. It is here (instead
of in a "Changes / Appendix" section) so that folk read it :-P
Other solutions to this problem were considered. There are mentioned
here to avoid having to have the discussion from the beginning
again.]
The original version of this document suggested simply serving an
empty root zone. This was tested, but found not to work. In order
to prevent poisining, recursive resolvers will only cache the
response if it comes from the closest enclosing zone. This was
tested in BIND both with and without 'minimal responses'. Thanks to
Mark Andrews for pointing this out.
Brian Dickson suggested that DNAME could be used (instead of
delegating to AS112, DNAME to "foo" and then "foo" could be the SOA.
We have not yet fully tested this idea, one concern would be how
widely deployed DNAME support is. This is still being considered.
Paul Vixie (and others) suggested a metazone solution. This is also
worth considering more. A possible concern is stale AXFRs.
9. IANA Considerations
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This document describes infrastructure which could be used in the
future to direct the IANA to delegate or redelegate infrastructure
zones under its administrative control.
However, this document makes no request of the IANA.
10. Security Considerations
The contents of the Security Considerations section of [RFC6304]
should be reviewed, since that discussion is pertinent to the
operation of Omniscient AS112 Servers as well as Existing AS112
Servers.
The deployment of Omniscient AS112 Servers enables new delegations to
AS112 Servers.
Queries received by an AS112 Server might reveal operational data for
which there is an expectation of privacy. For example, leaked
queries for an organisation's internal DNS names which are sent to an
AS112 Server might reveal the existence of those names to the AS112
Server operator. The delegation of new zones to AS112 Servers has
the potential to increase opportunities for such unintentional
information leakage.
The delegation of new zones to AS112 Servers has the potential to
increase the traffic received by those servers. AS112 Server
operators are encouraged to monitor traffic levels, and to take
appropriate steps if traffic levels threaten the stability of their
networks.
11. Acknowledgements
The authors thank and acknowledge the contributions of Dr Paul Vixie,
Ed Lewis, Bill Manning, George Michaelson, Mark Andrews, Shane Kerr,
Brian Dickson, S. Moonesamy, Chris Thompson, Nick Hilliard, Chris
Morrow, Paul Hoffman, Kurt Erik Lindqvist, Erik Kline, Roy Arends and
all the folk on the AS112 Project mailing lists in the preparation of
this document.
12. References
12.1. Normative References
[RFC1034] Mockapetris, P., "Domain names - concepts and facilities",
STD 13, RFC 1034, November 1987.
[RFC1035] Mockapetris, P., "Domain names - implementation and
specification", STD 13, RFC 1035, November 1987.
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[RFC2308] Andrews, M., "Negative Caching of DNS Queries (DNS
NCACHE)", RFC 2308, March 1998.
[RFC6304] Abley, J. and W. Maton, "AS112 Nameserver Operations", RFC
6304, July 2011.
12.2. Informative References
[BIND] Nominet UK, "Internet Systems Consortium, "BIND"", ,
<http://www.isc.org/>.
[RFC6303] Andrews, M., "Locally Served DNS Zones", BCP 163, RFC
6303, July 2011.
[evldns] Bellis, R., "evldns", ,
<http://code.google.com/p/evldns/>.
Appendix A. Implementation / "Running Code"
The "evldns" [evldns] library (written by Ray Bellis, Nominet UK)
includes an Omniscient AS112 Server implementation in the file
"oas112d.c"
Appendix B. Document Notes
This section (and sub-sections) contain information useful for
development and review of this document, and should be removed prior
to publication.
B.1. Venue
This document is an individual submission, and is not the product of
an IETF working group. However, a suitable venue for discussion is
the dnsop working group mailing list.
B.2. Textual Substitutions
The strings "IPv4-TBA1", "IPv4-TBA2" and "IPv4-TBA3" should be
replaced in this document should be replaced with IPv4 addresses
assigned for the purpose described. The covering IPv4 prefix for all
three addresses should replace the string "IPv4-PREFIX-TBA".
Similarly, the strings "IPv6-TBA1", "IPv6-TBA2", "IPv6-TBA3" and
"IPv6-PREFIX-TBA" should be substituted in the text with assigned
production values.
B.3. Open Questions
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1. Where to get IPv4 and IPv6 assignments from? There has already
been an assignment to DNS-OARC by ARIN for v6 service for AS112
servers.
B.4. Change History
Template:
o Initial draft
o Initial draft, circulated privately, not submitted.
-00:
o Rewrote much of the document (especially Section 4 to explain how
(and why) resonses should be generated.
o Updated "Updates to RFC 6304" section to explain the BIND does not
currently implement this, and so named.conf, etc should be
ignored.
o Removed example "empty" zone.
o Changed the addressing bit at the suggestion of SM.
-01:
o Document title changed to include the dnsop keyword, so that IETF
document automation can send courtesy notifications of document
actions to the dnsop working group.
o Abstract and introduction expanded.
o RFC2119 requirements notation removed, since this is an
informational document and any normative language would be
toothless.
o Discussion broken out into Protocol Considerations, Operational
Considerations and Addressing Considerations.
o Reverted to the custom software / synthesized answers.
o Added in the Ray Bellis evldns stuff.
-01 to -02:
o s/NoError/NXDomain/ -- Suggestion from Paul Vixie (and others).
"Nxd says there is no such name, no matter what the type was, and
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there are no children. No data/noerror says there are either
other types or children or both. We know what the truth must be
and we know which implications we want the requestor to follow.
Right?" -- Paul.
o Need to retest with empty root zone, and "minimal responses".
Initial test didn't seem to suppress the 'Negative Answers from
Authoritative Servers' (rfc2308)
o Removed the ''Editor note: [NoError was chosen instead of NXDOMAIN
because we did not think that we could reasonably return an SOA RR
which clearly indicates that the QNAME does exist, and also return
an NXDOMAIN.]" as we are now using NXDomain :-P
o This version submitted by Warren, with no real discussion with co-
authors. Trying to squeeze things under the -01 cutoff.
-02 to -03:
o "AS112 servers don't respond to transfers" -> AS112 respond, but
with REFUSED" -- thanks to Ed Lewis.
o Added an overview section. Before we just lept into protocol
discussions.
o And after much discussion on the list, and even more so in Orlando
we reverted to the NoError/NoData. See Orlando DNSOP audio
archives, around 50min.
o Added section 3.1 - DNSSEC
o Added Section 8 - Other Approaches. This section is
conversational.
B.4.1. draft-wkumari-dnsop-omniscient-as112-00
Document title changed to include the dnsop keyword, so that IETF
document automation can send courtesy notifications of document
actions to the dnsop working group.
Abstract and introduction expanded.
RFC2119 requirements notation removed, since this is an informational
document and any normative language would be toothless.
Discussion broken out into Protocol Considerations, Operational
Considerations and Addressing Considerations.
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Detailed updates to [RFC6304] added.
B.4.2. draft-wkumari-omniscient-as112-00
Authors' Addresses
Warren Kumari
Google
1600 Ampitheatre Parkway
Mountain View, CA 94043
USA
Email: warren@kumari.net
William F. Maton Sotomayor
National Research Council of Canada
1200 Montreal Road
Ottawa, ON K1A 0R6
Canada
Phone: +1 613 993 0880
Email: wfms@ryouko.imsb.nrc.ca
Joe Abley
ICANN
12025 Waterfront Drive, Suite 300
Los Angeles, CA 90094-2536
USA
Phone: +1 519 670 9327
Email: joe.abley@icann.org
Ray Bellis
Nominet UK
Edmund Halley Road
Oxford OX4 4DQ
United Kingdom
Phone: +44 1865 332211
Email: ray.bellis@nominet.org.uk
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