Internet DRAFT - draft-ietf-homenet-dot
draft-ietf-homenet-dot
Network Working Group P. Pfister
Internet-Draft Cisco Systems
Updates: RFC7788 (if approved) T. Lemon
Intended status: Standards Track Nominum, Inc.
Expires: March 5, 2018 September 1, 2017
Special Use Domain 'home.arpa.'
draft-ietf-homenet-dot-14
Abstract
This document specifies the behavior that is expected from the Domain
Name System with regard to DNS queries for names ending with
'.home.arpa.', and designates this domain as a special-use domain
name. 'home.arpa.' is designated for non-unique use in residential
home networks. Home Networking Control Protocol (HNCP) is updated to
use the 'home.arpa.' domain instead of '.home'.
Status of This Memo
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provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on March 5, 2018.
Copyright Notice
Copyright (c) 2017 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
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to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
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the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 3
3. General Guidance . . . . . . . . . . . . . . . . . . . . . . 3
4. Domain Name Reservation Considerations . . . . . . . . . . . 4
5. Updates to Home Networking Control Protocol . . . . . . . . . 6
6. Security Considerations . . . . . . . . . . . . . . . . . . . 7
6.1. Local Significance . . . . . . . . . . . . . . . . . . . 7
6.2. Insecure Delegation . . . . . . . . . . . . . . . . . . . 8
6.3. Bypassing Manually Configured Resolvers . . . . . . . . . 8
7. Delegation of 'home.arpa.' . . . . . . . . . . . . . . . . . 8
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 9
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 9
10.1. Normative References . . . . . . . . . . . . . . . . . . 9
10.2. Informative References . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11
1. Introduction
Users and devices within a home network (hereafter "homenet") require
devices and services to be identified by names that are unique within
the boundaries of the homenet [RFC7368]. The naming mechanism needs
to function without configuration from the user. While it may be
possible for a name to be delegated by an ISP, homenets must also
function in the absence of such a delegation. This document reserves
the name 'home.arpa.' to serve as the default name for this purpose,
with with a scope limited to each individual homenet.
This document corrects an error in [RFC7788], replacing '.home' with
'home.arpa.' as the default domain-name for homenets. '.home' had
been selected as the most user-friendly option. However, there are
existing uses of '.home' that may be in conflict with this use:
evidence indicates that '.home' queries frequently leak out and reach
the root name servers [ICANN1] [ICANN2].
In addition, it's necessary, for compatibility with DNSSEC
(Section 6), that an insecure delegation ([RFC4035] section 4.3) be
present for the name. There is an existing process for allocating
names under '.arpa.' [RFC3172]. No such process is available for
requesting a similar delegation in the root at the request of the
IETF, which does not administer that zone. As a result, all
unregistered uses of '.home' (that is, all current uses at the time
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of this document's publication), particularly as specified in
RFC7788, are deprecated.
This document registers the domain 'home.arpa.' as a special-use
domain name [RFC6761] and specifies the behavior that is expected
from the Domain Name System with regard to DNS queries for names
whose rightmost non-terminal labels are 'home.arpa.'. Queries for
names ending with '.home.arpa.' are of local significance within the
scope of a homenet, meaning that identical queries will result in
different results from one homenet to another. In other words, a
name ending in '.home.arpa.' is not globally unique.
Although this document makes specific reference to RFC7788, it is not
intended that the use of 'home.arpa.' be restricted solely to
networks where HNCP is deployed; it is rather the case that
'home.arpa.' is the correct domain for uses like the one described
for '.home' in RFC7788: local name service in residential homenets.
2. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
3. General Guidance
The domain name 'home.arpa.' is to be used for naming within
residential homenets. Names ending with '.home.arpa.' reference a
locally-served zone, the contents of which are unique only to a
particular homenet, and are not globally unique. Such names refer to
nodes and/or services that are located within a homenet (e.g., a
printer, or a toaster).
DNS queries for names ending with '.home.arpa.' are resolved using
local resolvers on the homenet. Such queries MUST NOT be recursively
forwarded to servers outside the logical boundaries of the homenet.
Some service discovery user interfaces that are expected to be used
on homenets conceal information such as domain names from end users.
However, it is still expected that in some cases, users will need to
see, remember, and even type, names ending with '.home.arpa.'. The
working group hopes that this name will in some way indicate to as
many readers as possible that such domain names are referring to
devices in the home, but we recognize that it is an imperfect
solution.
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4. Domain Name Reservation Considerations
This section specifies considerations for systems involved in domain
name resolution when resolving queries for names ending with
'.home.arpa.'. Each item in this section addresses some aspect of
the DNS or the process of resolving domain names that would be
affected by this special use allocation. Detailed explanations of
these items can be found in [RFC6761], Section 5.
1. Users can use names ending with '.home.arpa.' just as they would
use any other domain name. The 'home.arpa.' name is chosen to be
readily recognized by users as signifying that the name is
addressing a service on the homenet to which the user's device is
connected.
2. Application software SHOULD NOT treat names ending in
'.home.arpa.' differently than other names. In particular, there
is no basis for trusting names that are subdomains of
'home.arpa.' (see Section 6).
3. Name resolution APIs and libraries MUST NOT recognize names that
end in '.home.arpa.' as special and MUST NOT treat them as having
special significance, except that it may be necessary that such
APIs not bypass the locally configured recursive resolvers.
One or more IP addresses for recursive DNS servers will usually
be supplied to the client through router advertisements or DHCP.
For an administrative domain that uses subdomains of
'home.arpa.', such as a homenet, the recursive resolvers provided
by that domain will be able to answer queries for subdomains of
'home.arpa.'; other resolvers will not, or will provide answers
that are not correct within that administrative domain.
A host that is configured to use a resolver other than one that
has been provided by the local network may be unable to resolve,
or may receive incorrect results for, subdomains of 'home.arpa.'.
In order to avoid this, it is permissible that hosts use the
locally-provided resolvers for resolving 'home.arpa.' even when
they are configured to use other resolvers.
4.
A. Recursive resolvers at sites using 'home.arpa.' MUST
transparently support DNSSEC queries: queries for DNSSEC
records and queries with the DO bit set ([RFC4035] section
3.2.1). While validation is not required, it is strongly
encouraged: a caching recursive resolver that does not
validate answers that can be validated may cache invalid
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data. This in turn will prevent validating stub resolvers
from successfully validating answers.
B. Unless configured otherwise, recursive resolvers and DNS
proxies MUST behave as described in Locally Served Zones
([RFC6303] Section 3). That is, queries for 'home.arpa.' and
subdomains of 'home.arpa.' MUST NOT be forwarded, with one
important exception: a query for a DS record with the DO bit
set MUST return the correct answer for that question,
including correct information in the authority section that
proves that the record is nonexistent.
So for example a query for the NS record for 'home.arpa.'
MUST NOT result in that query being forwarded to an upstream
cache nor to the authoritative DNS server for '.arpa.'.
However, as necessary to provide accurate authority
information, a query for the DS record MUST result in
whatever queries are necessary being forwarded; typically,
this will just be a query for the DS record, since the
necessary authority information will be included in the
authority section of the response if the DO bit is set.
C. In addition to the behavior specified above, recursive
resolvers that can be used in a homenet MUST be configurable
to forward queries for 'home.arpa.' and subdomains of
'home.arpa.' to an authoritative server for 'home.arpa.'.
This server will provide authoritative data for 'home.arpa.'
within a particular homenet. The special handling for DS
records for the 'home.arpa.' delegation is still required.
It is permissible to combine the recursive resolver function
for general DNS lookups with an authoritative resolver for
'home.arpa.'; in this case, rather than forwarding queries
for subdomains of 'home.arpa.' to an authoritative server,
the resolver answers them authoritatively. The behavior with
respect to forwarding queries specifically for 'home.arpa.'
remains the same.
5. No special processing of 'home.arpa.' is required for
authoritative DNS server implementations. It is possible that an
authoritative DNS server might attempt to check the authoritative
servers for 'home.arpa.' for a delegation beneath that name
before answering authoritatively for such a delegated name. In
such a case, because the name always has only local significance
there will be no such delegation in the 'home.arpa.' zone, and so
the server would refuse to answer authoritatively for such a
zone. A server that implements this sort of check MUST be
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configurable so that either it does not do this check for the
'home.arpa.' domain, or it ignores the results of the check.
6. DNS server operators MAY configure an authoritative server for
'home.arpa.' for use in homenets and other home networks. The
operator for the DNS servers authoritative for 'home.arpa.' in
the global DNS will configure any such servers as described in
Section 7.
7. 'home.arpa.' is a subdomain of the 'arpa' top-level domain, which
is operated by IANA under the authority of the Internet
Architecture Board according to the rules established in
[RFC3172]. There are no other registrars for .arpa.
5. Updates to Home Networking Control Protocol
The final paragraph of Home Networking Control Protocol [RFC7788],
section 8, is updated as follows:
OLD:
Names and unqualified zones are used in an HNCP network to provide
naming and service discovery with local significance. A network-
wide zone is appended to all single labels or unqualified zones in
order to qualify them. ".home" is the default; however, an
administrator MAY configure the announcement of a Domain-Name TLV
(Section 10.6) for the network to use a different one. In case
multiple are announced, the domain of the node with the greatest
node identifier takes precedence.
NEW:
Names and unqualified zones are used in an HNCP network to provide
naming and service discovery with local significance. A network-
wide zone is appended to all single labels or unqualified zones in
order to qualify them. 'home.arpa.' is the default; however, an
administrator MAY configure the announcement of a Domain-Name TLV
(Section 10.6) for the network to use a different one. In case
multiple are announced, the domain of the node with the greatest
node identifier takes precedence.
The 'home.arpa.' special-use name does not require a special
resolution protocol. Names for which the rightmost two labels are
'home.arpa.' are resolved using the DNS protocol [RFC1035].
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6. Security Considerations
6.1. Local Significance
A DNS record that is returned as a response to a query for an FQDN
that is a subdomain of 'home.arpa.' is expected to have local
significance. It is expected to be returned by a server involved in
name resolution for the homenet the device is connected in. However,
such response MUST NOT be considered more trustworthy than would be a
similar response for any other DNS query.
Because 'home.arpa.' is not globally scoped and cannot be secured
using DNSSEC based on the root domain's trust anchor, there is no way
to tell, using a standard DNS query, in which homenet scope an answer
belongs. Consequently, users may experience surprising results with
such names when roaming to different homenets.
To prevent this from happening, it could be useful for the resolver
on the host to securely differentiate between different homenets, and
between identical names on different homenets. However, a mechanism
for doing this has not yet been standardized, and doing so is out of
scope for this document. It is expected that this will be explored
in future work.
Locally Served Zones ([RFC6303] section 7) recommends installing
trust anchors for locally served zones. However, in order for this
to be effective, there must be some way of configuring the trust
anchor in the host. Homenet currently specifies no mechanism for
configuring such trust anchors. As a result, while this advice
sounds good, it is not practicable.
Also, although in principle it might be useful to install a trust
anchor for a particular instance of 'home.arpa.', it's reasonable to
expect that a host with such a trust anchor might from time to time
connect to more than one network with its own instance of
'home.arpa.'. Such a host would be unable to access services on any
instance of 'home.arpa.' other than the one for which a trust anchor
was configured.
It is in principle possible to attach an identifier to an instance of
'home.arpa.' that could be used to identify which trust anchor to
rely on for validating names in that particular instance. However,
the security implications of this are complicated, and such a
mechanism, as well as a discussion of those implications, is out of
scope for this document.
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6.2. Insecure Delegation
It is not possible to install a trust anchor (a DS RR) for this zone
in the '.arpa' zone. The reason for this is that in order to do so,
it would be necessary to have the key-signing key for the zone
([RFC4034] Section 5). Since the zone is not globally unique, no one
key would work.
An alternative would be to provide a authenticated denial of
existence ([RFC4033] Section 3.2). This would be done simply by not
having a delegation from the 'arpa.' zone. However, this requires
the validating resolver to treat 'home.arpa.' specially. If a
validating resolver that doesn't treat 'home.arpa.' specially
attempts to validate a name in 'home.arpa.', an authenticated denial
of existence of 'home' as a subdomain of 'arpa.' would cause the
validation to fail. Therefore, the only delegation that will allow
names under 'home.arpa.' to be resolved by all validating resolvers
is an insecure delegation as in [RFC6303] section 7.
Consequently, unless a trust anchor for the particular instance of
the 'home.arpa.' zone being validated is manually configured on the
validating resolver, DNSSEC signing and validation of names within
the 'home.arpa.' zone is not possible.
6.3. Bypassing Manually Configured Resolvers
In Section 4, item 3, an exception is made to the behavior of stub
resolvers allowing them to query local resolvers for subdomains of
'home.arpa.' even when they have been manually configured to use
other resolvers. This behavior obviously has security and privacy
implications, and may not be desirable depending on the context. It
may be better to simply ignore this exception and, when one or more
recursive resolvers are configured manually, simply fail to provide
correct answers for subdomains of 'home.arpa.'. At this time we do
not have operational experience that would guide us in making this
decision; implementors are encouraged to consider the context in
which their software will be deployed when deciding how to resolve
this question.
7. Delegation of 'home.arpa.'
In order to be fully functional, there must be a delegation of
'home.arpa.' in the '.arpa.' zone [RFC3172]. This delegation MUST
NOT include a DS record, and MUST point to one or more black hole
servers, for example 'blackhole-1.iana.org.' and 'blackhole-
2.iana.org.'. The reason that this delegation must not be signed is
that not signing the delegation breaks the DNSSEC chain of trust,
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which prevents a validating stub resolver from rejecting names
published under 'home.arpa.' on a homenet name server.
8. IANA Considerations
IANA is requested to record the domain name 'home.arpa.' in the
Special-Use Domain Names registry [SUDN]. IANA is requested, with
the approval of IAB, to implement the delegation requested in
Section 7.
IANA is further requested to create a new subregistry within the
"Locally-Served DNS Zones" registry [LSDZ], titled "Transport-
Independent Locally-Served DNS Zones", with the same format as the
other subregistries. IANA is requested to add an entry in this new
registry for 'home.arpa.' with the description "Homenet Special-Use
Domain", listing this document as the reference. The registration
procedure for this subregistry should be the same as for the others,
currently "IETF Review" ([RFC8126] Section 4.8).
9. Acknowledgments
The authors would like to thank Stuart Cheshire for his prior work on
'.home', as well as the homenet chairs: Mark Townsley and Ray Bellis.
We would also like to thank Paul Hoffman for providing review and
comments on the IANA considerations section, Andrew Sullivan for his
review and proposed text, and Suzanne Woolf and Ray Bellis for their
very detailed review comments and process insights. Thanks to Mark
Andrews for providing an exhaustive reference list on the topic of
insecure delegations. Thanks to Dale Worley for catching a rather
egregious mistake and for the Gen-Art review, and to Daniel Migault
for a thorough SecDir review. Thanks to Warren Kumari for catching
some additional issues, and to Adam Roach for some helpful
clarifications.
10. References
10.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, <https://www.rfc-
editor.org/info/rfc2119>.
[RFC3172] Huston, G., Ed., "Management Guidelines & Operational
Requirements for the Address and Routing Parameter Area
Domain ("arpa")", BCP 52, RFC 3172, DOI 10.17487/RFC3172,
September 2001, <https://www.rfc-editor.org/info/rfc3172>.
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[RFC4035] Arends, R., Austein, R., Larson, M., Massey, D., and S.
Rose, "Protocol Modifications for the DNS Security
Extensions", RFC 4035, DOI 10.17487/RFC4035, March 2005,
<https://www.rfc-editor.org/info/rfc4035>.
[RFC6303] Andrews, M., "Locally Served DNS Zones", BCP 163,
RFC 6303, DOI 10.17487/RFC6303, July 2011,
<https://www.rfc-editor.org/info/rfc6303>.
[RFC6761] Cheshire, S. and M. Krochmal, "Special-Use Domain Names",
RFC 6761, DOI 10.17487/RFC6761, February 2013,
<https://www.rfc-editor.org/info/rfc6761>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
10.2. Informative References
[ICANN1] "New gTLD Collision Risk Mitigation", October 2013,
<https://www.icann.org/en/system/files/files/new-gtld-
collision-mitigation-05aug13-en.pdf>.
[ICANN2] "New gTLD Collision Occurence Management", October 2013,
<https://www.icann.org/en/system/files/files/resolutions-
new-gtld-annex-1-07oct13-en.pdf>.
[LSDZ] "Locally-Served DNS Zones Registry", July 2011,
<https://www.iana.org/assignments/locally-served-dns-
zones/locally-served-dns-zones.xhtml>.
[RFC1035] Mockapetris, P., "Domain names - implementation and
specification", STD 13, RFC 1035, DOI 10.17487/RFC1035,
November 1987, <https://www.rfc-editor.org/info/rfc1035>.
[RFC4033] Arends, R., Austein, R., Larson, M., Massey, D., and S.
Rose, "DNS Security Introduction and Requirements",
RFC 4033, DOI 10.17487/RFC4033, March 2005,
<https://www.rfc-editor.org/info/rfc4033>.
[RFC4034] Arends, R., Austein, R., Larson, M., Massey, D., and S.
Rose, "Resource Records for the DNS Security Extensions",
RFC 4034, DOI 10.17487/RFC4034, March 2005,
<https://www.rfc-editor.org/info/rfc4034>.
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[RFC7368] Chown, T., Ed., Arkko, J., Brandt, A., Troan, O., and J.
Weil, "IPv6 Home Networking Architecture Principles",
RFC 7368, DOI 10.17487/RFC7368, October 2014,
<https://www.rfc-editor.org/info/rfc7368>.
[RFC7788] Stenberg, M., Barth, S., and P. Pfister, "Home Networking
Control Protocol", RFC 7788, DOI 10.17487/RFC7788, April
2016, <https://www.rfc-editor.org/info/rfc7788>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>.
[SUDN] "Special-Use Domain Names Registry", July 2012,
<https://www.iana.org/assignments/special-use-domain-
names/special-use-domain-names.xhtml>.
Authors' Addresses
Pierre Pfister
Cisco Systems
Paris
France
Email: pierre.pfister@darou.fr
Ted Lemon
Nominum, Inc.
800 Bridge Parkway
Redwood City, California 94065
United States of America
Phone: +1 650 381 6000
Email: ted.lemon@nominum.com
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