Internet DRAFT - draft-richardson-ipv4-reverse-in-v6
draft-richardson-ipv4-reverse-in-v6
Homenet M. Richardson
Internet-Draft Sandelman Software Works
Intended status: Standards Track 8 December 2022
Expires: 11 June 2023
Simple Provisioning of Reverse IPv4 Names
draft-richardson-ipv4-reverse-in-v6-01
Abstract
Merges IPv4 reverse names into IPv6 reverse maps, particularly for
IPv6 delegations that are managed automatically.
About This Document
This note is to be removed before publishing as an RFC.
Status information for this document may be found at
https://datatracker.ietf.org/doc/draft-richardson-ipv4-reverse-in-
v6/.
Discussion of this document takes place on the homenet Working Group
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Source for this draft and an issue tracker can be found at
https://github.com/mcr/ipv4-reverse-dns.git.
Status of This Memo
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This Internet-Draft will expire on 11 June 2023.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Protocol Proposal . . . . . . . . . . . . . . . . . . . . . . 3
2.1. Operator changes . . . . . . . . . . . . . . . . . . . . 4
2.2. Home Naming Architecture (HNA) changes . . . . . . . . . 4
3. Security Considerations . . . . . . . . . . . . . . . . . . . 4
4. References . . . . . . . . . . . . . . . . . . . . . . . . . 4
4.1. Normative References . . . . . . . . . . . . . . . . . . 4
4.2. Informative References . . . . . . . . . . . . . . . . . 5
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 5
1. Introduction
Many small offices get customized service from boutique ISPs. This
has historically included delegation of one or a small number (8 to
16) of statically assigned IPv4 addresses.
Populating the reverse zone for such small delegations has often
meant using [RFC2317] style delegation.
[RFC2317] delegation still requires that the ISP delegate the zone to
the customer, collect NS and DS records, and in most cases, that the
ISP arranges to become a secondary for the zone.
Experience by early adopters was that not every stub resolver would
do a second query when a CNAME record was found in the reverse zone
rather than a PTR, but if the PTR was returned as additional
information in the same query, that it would in fact work. (Later
specifications make stub resolvers ignore this additional
information. Resolvers that paid attention to that update, also
likely would follow the CNAME in the reverse.)
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This custom configuration required to do [RFC2317] delegation often
has been a drag for many operators, and in some cases has resulted in
delays to making IPv6 available to this smaller offices. The
rationale is that IPv6 operations can only be scaled well when
completely automated, and the custom configurations for the IPv4
delegation gets in the way of such things.
This document proposes to leverage the work of
[I-D.ietf-homenet-front-end-naming-delegation] and
[I-D.ietf-homenet-naming-architecture-dhc-options] to automate the
delegation of [RFC2317] reverse zones for IPv4 delegations.
2. Protocol Proposal
[RFC2317] initially proposes to make the delegated zone a subzone of
the IPv4 reverse, such as having '128/26.2.0.192.in-addr.arpa' be the
delegation from '2.0.192.in-addr.arpa'
(The use of '/' as the separator has become a problem for many
operators due the way that zone names are translated to file names,
and has often been replaced with another character like '-')
In [RFC2317], Section 5.2 suggests putting the reverse names into the
forward zone. This document proposes to put the IPv4 reverse names
into the IPv6 reverse zone, which can be automatically delegated to
the Home Naming Architecture described in
[I-D.ietf-homenet-front-end-naming-delegation].
All of this can be done today through bilateral convention: as long
as the HNA and the ISP's IPv4 Address Management system agree to use
the same names in the CNAMEs, everything works. This document
proposes a universal mechanism to enable interoperation without
bilateral agreement.
IPv4 reverse names are done by octet in decimal, while IPv6 is done
by hexadecimal digit by nibble. In order to allow for the maximum
interoperation for cases where multiple IPv4 addresses are delegated,
but not from the same prefix, all IPv4 octets should be included in
the mapped address.
It is therefore proposed that the reverse name for an address
192.0.2.234, where the customer has the IPv6 prefix
2001:db8:cake::/64 delegated, be mapped as follows:
234.2.0.192.in-addr.arpa IN CNAME 234.2.0.192.0.0.0.0.e.k.a.c.8.d.b.0.1.0.0.2.ip6.arpa.
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Note that the resulting name in the IP6 space will always be shorter
than any IPv6 name, so even if a number like 8.8.8.8 were mapped
(which could very well be read as an IPv6 nibble grouping), there
should never be a conflict.
2.1. Operator changes
The only thing that the operator has to do differently is to insert
the right CNAMEs into its reverse IPv4 DNS. These can be generated
by a custom script for their IP Address Manager which will know what
IPv6 delegations have been made, and which IPv4 static delegations
are involved.
All of the DNS operational activities like DNSSEC, NS records, and
the like would now be handled by the mechanisms of
[I-D.ietf-homenet-front-end-naming-delegation] and
[I-D.ietf-homenet-naming-architecture-dhc-options].
2.2. Home Naming Architecture (HNA) changes
The HNA mechanism responsible for creating the reverse map needs to
take into account any static IPv4 addresses that are delegated to it.
This may be via PPP IPCP, or DHCPv4 for the first address, and by
some IPv4 as a service to get additional addresses. It is probably
that the addresses will have to be statically configured for some
time. (Note that the services described by [RFC9313] are all
mechanisms to share an IPv4 among many subscribers, not delegate a
single IPv4 address)
For an address like 192.0.2.234, with a reverse name of
"webserver.example", then it must create a new PTR record like:
234.2.0.192.0.0.0.0.e.k.a.c.8.d.b.0.1.0.0.2.ip6.arpa IN PTR webserver.example.
3. Security Considerations
The presence of the additional PTR records may be easily enumerated
due to the much smaller IPv4 space. That will reveal which names are
active in IPv4 space for the enterprise using this technique.
4. References
4.1. Normative References
[I-D.ietf-homenet-front-end-naming-delegation]
Migault, D., Weber, R., Richardson, M., and R. Hunter,
"Simple Provisioning of Public Names for Residential
Networks", Work in Progress, Internet-Draft, draft-ietf-
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homenet-front-end-naming-delegation-24, 5 December 2022,
<https://datatracker.ietf.org/doc/html/draft-ietf-homenet-
front-end-naming-delegation-24>.
[I-D.ietf-homenet-naming-architecture-dhc-options]
Migault, D., Weber, R., and T. Mrugalski, "DHCPv6 Options
for Home Network Naming Authority", Work in Progress,
Internet-Draft, draft-ietf-homenet-naming-architecture-
dhc-options-24, 31 October 2022,
<https://datatracker.ietf.org/doc/html/draft-ietf-homenet-
naming-architecture-dhc-options-24>.
[RFC2317] Eidnes, H., de Groot, G., and P. Vixie, "Classless IN-
ADDR.ARPA delegation", BCP 20, RFC 2317,
DOI 10.17487/RFC2317, March 1998,
<https://www.rfc-editor.org/rfc/rfc2317>.
4.2. Informative References
[RFC9313] Lencse, G., Palet Martinez, J., Howard, L., Patterson, R.,
and I. Farrer, "Pros and Cons of IPv6 Transition
Technologies for IPv4-as-a-Service (IPv4aaS)", RFC 9313,
DOI 10.17487/RFC9313, October 2022,
<https://www.rfc-editor.org/rfc/rfc9313>.
Author's Address
Michael Richardson
Sandelman Software Works
470 Dawson Avenue
Ottawa, ON K1Z 5V7
Canada
Email: mcr+ietf@sandelman.ca
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