Independent Submission T. Manderson
Request for Comments: 7745 ICANN
Category: Informational January 2016
ISSN: 2070-1721
XML Schemas for Reverse DNS Management
Abstract
This document defines an Extensible Markup Language (XML) schema for
reverse DNS management in a tightly controlled Representational State
Transfer (REST) environment. This document describes a schema that
has been developed and deployed by ICANN in a "RESTful" system since
2011 and is being used by the registries responsible for reverse DNS
(rDNS) delegations underneath IN-ADDR.ARPA and IP6.ARPA through an
HTTPS transaction that is mediated by an X.509 certificate.
Status of This Memo
This document is not an Internet Standards Track specification; it is
published for informational purposes.
This is a contribution to the RFC Series, independently of any other
RFC stream. The RFC Editor has chosen to publish this document at
its discretion and makes no statement about its value for
implementation or deployment. Documents approved for publication by
the RFC Editor are not a candidate for any level of Internet
Standard; see Section 2 of RFC 5741.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/RFC 7745.
Copyright Notice
Copyright (c) 2016 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.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 3
3. Implementation . . . . . . . . . . . . . . . . . . . . . . . 3
4. Security Considerations . . . . . . . . . . . . . . . . . . . 5
5. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
5.1. Normative References . . . . . . . . . . . . . . . . . . 5
5.2. Informative References . . . . . . . . . . . . . . . . . 6
Appendix A. Schema Definition for rDNS Updates . . . . . . . . . 7
Appendix B. Schema Definition for rDNS Queue Entries . . . . . . 8
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 10
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 10
1. Introduction
This document defines an Extensible Markup Language (XML) schema for
reverse DNS management in a tightly controlled Representational State
Transfer (REST) [REST] environment. This document describes a schema
that has been developed and deployed by ICANN in a "RESTful" system
since 2011 and is being used by the registries responsible for
reverse DNS (rDNS) delegations underneath IN-ADDR.ARPA [RFC 1034] and
IP6.ARPA [RFC 3596] through an HTTPS [RFC 2818] transaction that is
mediated by an X.509 [RFC 5280] certificate.
As DNSSEC [RFC 4033] adoption progresses, the necessity to interact
with a delegation in the IN-ADDR.ARPA and IP6.APRA zones becomes more
frequent given that updates to DS records in the parent zone for
child delegations follow the key rollover and expiry of the child
zone. The modification of such critical areas at a relative high
frequency requires a system that allows the administrative holders of
such delegations to make such changes in a secure and trustworthy
manner where the chain of trust for submitting the necessary
information remains unbroken between the IN-ADDR.ARPA and IP6.APRA
zone maintainers and the zone customers.
At the request of the Regional Internet Registries (RIRs) to automate
reverse DNS updates with ICANN, a REST-based HTTPS service was
deployed that:
o Provides for a secure, authenticated mechanism to update zone data
(NS and DS records)
o Provides a well-formed data structure for both the IN-ADDR.ARPA
and IP6.ARPA zones
o Allows for "out-of-band" acknowledgement and notification of
updates
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2. Requirements Language
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 [RFC 2119].
3. Implementation
The implemented system allows the entity responsible for its rDNS
delegations to effect changes in the reverse DNS zones IN-ADDR.ARPA
and IP6.ARPA by submitting an XML document to an atomic RESTful
service via an HTTPS [RFC 2818] connection. In this service, the
HTTPS layer provides the end-to-end security of the transaction, and
it further provides authentication by use of mandatory X.509
[RFC 5280] client certificates with a known server certificate issued
by a Certification Authority administered by the service operator.
Certificates for use in this system, issued by the system operator,
are specific to the entity responsible for the delegations in the
zone.
Updates are made to the system by using the HTTP GET, PUT, and DELETE
operations over HTTP 1.1 [RFC 7231] via HTTPS [RFC 2818] only. These
operations are sent to a resource Uniform Resource Identifier (URI)
in the form of:
https://host.example.org/<ipversion>/<zone>
A synthetic example of an XML document submitted to the deployed
system might take the following form (including all optional
attributes) as per the schema in Appendix A.
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<zone xmlns="http://download.research.icann.org/rdns/1.1"
name="10.in-addr.arpa" cust="IANA" ipversion="ipv4"
version="1.1" modified="2012-01-18T01:00:06"
state="active" href="https://host.example.org/ipv4/10">
<nserver>
<fqdn>BLACKHOLE-1.IANA.ORG.fqdn>
nserver>
<nserver>
<fqdn>BLACKHOLE-2.IANA.ORG.fqdn>
nserver>
<ds>
<rdata>33682 5 1 ea8afb5fce7caf381ab101039rdata>
ds>
<ds>
<rdata>33682 5 2 7d44874f1d93aaceb793a88001739ardata>
ds>
zone>
When PUT and DELETE operations are used, the well-formed XML is
required to be sent with the appropriate content-length headers. The
GET operation requires only the URI.
One requirement of the system was to allow the separation of update
and approval with an out-of-band notification mechanism. When such
options are configured for a customer of the service, submitted
updates may be queued for later approval. When a customer has queued
updates pending approval, the customer may submit a GET request to
retrieve either an individual entry or a full listing of all queued
entries.
To fetch a listing of the customer's queue, the customer would GET a
URI in the form of:
https://host.example.org/queuelist
To fetch an individual queue entry, the customer would GET the
canonical URL (as per the schema) for this queue record:
https://host.example.org/queue/<identifier>
Where <identifier> is a system-generated and system-specific value
that identifies this particular queue entry. All XML returned from
queue-based operations ('queue' and 'queuelist') would return an XML
document following the specification in Appendix B. A synthetic
example from a GET of 'queuelist' would be:
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<queuelist xmlns="http://download.research.icann.org/rq/1.0"
version="1.0">
<queue xmlns="http://download.research.icann.org/rq/1.0"
name="10.in-addr.arpa" cust="IANA" ipversion="ipv4"
version="1.0" submitted="2013-01-11T05:22:15"
state="pending" method="PUT"
ack="https://host.example.org/ack/25a531f50e5ba45"
href="https://host.example.org/queue/25a531f50e5ba45">
<nserver>
<fqdn>BLACKHOLE-1.IANA.ORG.fqdn>
nserver>
<nserver>
<fqdn>BLACKHOLE-2.IANA.ORG.fqdn>
nserver>
<ds>
<rdata>33682 5 1 ea8afb5fce7caf381ab101039rdata>
ds>
<ds>
<rdata>33682 5 2 7d44874f1d93aaceb793a88001739ardata>
ds>
queue>
queuelist>
4. Security Considerations
This document provides an XML schema for facilitating the management
of reverse DNS delegations in the IN-ADDR.ARPA and IP6.APRA zones.
The schema itself contains no authentication data, and all other
information contained is considered public data as it is either
published in DNS or propagated to other public information sources
like WHOIS.
The system that implements this XML schema requires HTTPS to be used
and also uses known server and client X.509 certificates for
authentication to protect against message modification, message
insertion/deletion, man-in-the-middle, and replay attacks. Any
DoS-type attack vectors and the authorisation of which delegations
the X.509 certificate authentication sessions can affect are out of
scope for this document.
5. References
5.1. Normative References
[RFC 1034] Mockapetris, P., "Domain names - concepts and facilities",
STD 13, RFC 1034, DOI 10.17487/RFC 1034, November 1987,
<http://www.rfc-editor.org/info/RFC 1034>.
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[RFC 2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC 2119, March 1997,
<http://www.rfc-editor.org/info/RFC 2119>.
[RFC 2818] Rescorla, E., "HTTP Over TLS", RFC 2818,
DOI 10.17487/RFC 2818, May 2000,
<http://www.rfc-editor.org/info/RFC 2818>.
[RFC 3596] Thomson, S., Huitema, C., Ksinant, V., and M. Souissi,
"DNS Extensions to Support IP Version 6", RFC 3596,
DOI 10.17487/RFC 3596, October 2003,
<http://www.rfc-editor.org/info/RFC 3596>.
[RFC 4033] Arends, R., Austein, R., Larson, M., Massey, D., and S.
Rose, "DNS Security Introduction and Requirements",
RFC 4033, DOI 10.17487/RFC 4033, March 2005,
<http://www.rfc-editor.org/info/RFC 4033>.
[RFC 5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
Housley, R., and W. Polk, "Internet X.509 Public Key
Infrastructure Certificate and Certificate Revocation List
(CRL) Profile", RFC 5280, DOI 10.17487/RFC 5280, May 2008,
<http://www.rfc-editor.org/info/RFC 5280>.
[RFC 7231] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Semantics and Content", RFC 7231,
DOI 10.17487/RFC 7231, June 2014,
<http://www.rfc-editor.org/info/RFC 7231>.
5.2. Informative References
[RELAXNG] The Organization for the Advancement of Structured
Information Standards (OASIS), "RELAX NG Compact Syntax",
November 2002, <https://www.oasis-open.org/committees/
relax-ng/compact-20021121.html>.
[REST] Fielding, R., "Architectural Styles and the Design of
Network-based Software Architectures", PhD
Dissertation, University of California, Irvine,
ISBN 0-599-87118-0, 2000.
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Appendix A. Schema Definition for rDNS Updates
The following Schema, used for PUT, GET, and DELETE operations, is an
XML document using the RelaxNG Compact [RELAXNG] specification.
default namespace = "http://download.research.icann.org/rdns/1.1"
# A document may either be a single zone (update) or
# a collection of zones (view)
start = zone | zonelist | zonereflist
# A list of zone names for view only.
zonereflist = element zonereflist {
attribute version {
xsd:decimal { minInclusive="1.1" fractionDigits="1" }
},
zoneref*
}
# A bulk list of zones for view only.
zonelist = element zonelist {
attribute version {
xsd:decimal { minInclusive="1.1" fractionDigits="1" }
},
zone*
}
# A zone reference (accepted by REST engine for query)
zoneref = element zoneref {
attribute name { text },
attribute href { xsd:anyURI }
}
# A single zone record
zone = element zone {
# The zone record's name, e.g., 10.in-addr.arpa
attribute name { text },
# The customer (optional); derived from known state.
attribute cust { text }?,
# The canonical URL for this zone record (optional)
attribute href { xsd:anyURI }?,
# The IP version of the address for the zone record (optional)
attribute ipversion { "ipv4" | "ipv6" }?,
# The administrative state of the zone (optional)
attribute state { "active" | "pending" | "error" }?,
# The last modified timestamp in UTC (optional)
attribute modified { xsd:dateTime }?,
# The schema version (optional)
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attribute version {
xsd:decimal { minInclusive="1.1" fractionDigits="1" }
}?,
# A zone NS RRset MUST have at least two NS records
nserver,
nserver+,
# It MAY contain some DS records
ds*
}
# DNS-SEC records
ds = element ds {
# rdata MUST contain
# <Keytag> | <Algorithm> | <Digest type> | <Digest>
# as per RFC 4034
#
element rdata { text }
}
# A single name server
nserver = element nserver {
# An nserver entry MUST contain a DNS FQDN
# for a NS RR (RFC 1035)
element fqdn { text }
}
Appendix B. Schema Definition for rDNS Queue Entries
The XML schema definition below, in RelaxNG Compact [RELAXNG] form is
used for queue interaction operations.
default namespace = "http://download.research.icann.org/rq/1.0"
# A document MAY either be a single queue entry
# or a collection of queued entries
start = queue | queuelist
# A list of zone names for view only.
queuelist = element queuelist {
attribute version {
xsd:decimal { minInclusive="1.0" fractionDigits="0" }
},
queue*
}
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# A single queued zone record
queue = element queue {
# The zone record's name, e.g., 10.in-addr.arpa
attribute name { text },
# The customer (optional); derived from known state.
attribute cust { text }?,
# The canonical URL for this queue record (optional)
attribute href { xsd:anyURI }?,
# The acknowledgement URL for this queue record (optional)
attribute ack { xsd:anyURI }?,
# The IP version of the address for the zone record (optional)
attribute ipversion { "ipv4" | "ipv6" }?,
# The state of the zone (optional); for a queue, it
# SHOULD always be pending
attribute state { "pending" }?,
# The submitted timestamp (optional)
attribute submitted { xsd:dateTime }?,
# The HTTP method used to update
attribute method { "PUT" | "DELETE" },
# The schema version (1.0) (optional)
attribute version {
xsd:decimal { minInclusive="1.0" fractionDigits="1" }
}?,
# A zone NS RRset must have at least two NS records
nserver,
nserver+,
# It MAY contain some DS records
ds*
}
# DNS-SEC records
ds = element ds {
# rdata MUST contain Flags | Protocol | Algorithm | Public Key
# as per RFC 4034
#
element rdata { text }
}
# A single name server
nserver = element nserver {
# An nserver entry MUST contain a DNS FQDN
# for a NS RR (RFC 1035)
element fqdn { text }
}
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Acknowledgements
An XML schema was initially provided by APNIC; however, necessity
required a branch, and as such a new namespace and schema have been
created. Recognition goes to APNIC for prior efforts in this area.
The author acknowledges feedback from a collective made up of various
RIR technical folk; however, heartfelt thanks goes to Anand Buddhdev
of the RIPE-NCC and Robert Loomans of APNIC for being both alpha and
beta testers and providing valuable feedback.
Author's Address
Terry Manderson
ICANN
Email: terry.manderson@icann.org
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