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Independent Submission E. Rye
Request for Comments: 8567 R. Beverly
Category: Informational CMAND
ISSN: 2070-1721 1 April 2019
Customer Management DNS Resource Records
Abstract
Maintaining high Quality of Experience (QoE) increasingly requires
end-to-end, holistic network management, including managed Customer
Premises Equipment (CPE). Because customer management is a shared
global responsibility, the Domain Name System (DNS) provides an ideal
existing infrastructure for maintaining authoritative customer
information that must be readily, reliably, and publicly accessible.
This document describes four new DNS resource record types for
encoding customer information in the DNS. These records are intended
to better facilitate high customer QoE via inter-provider cooperation
and management of customer data.
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 candidates for any level of Internet Standard;
see Section 2 of RFC 7841.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc8567.
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RFC 8567 Customer Management over DNS 1 April 2019
Copyright Notice
Copyright (c) 2019 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
(https://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.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
2. Customer Management Resource Records . . . . . . . . . . . . 3
2.1. The PASSWORD Resource Record . . . . . . . . . . . . . . 4
2.2. The CREDITCARD Resource Record . . . . . . . . . . . . . 4
2.3. The SSN Resource Record . . . . . . . . . . . . . . . . . 6
2.4. The SSNPTR Resource Record . . . . . . . . . . . . . . . 7
3. Related RR Types . . . . . . . . . . . . . . . . . . . . . . 7
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
5. Security Considerations . . . . . . . . . . . . . . . . . . . 8
6. References . . . . . . . . . . . . . . . . . . . . . . . . . 9
6.1. Normative References . . . . . . . . . . . . . . . . . . 9
6.2. Informative References . . . . . . . . . . . . . . . . . 9
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 11
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11
1. Introduction
A significant portion of today's Internet is comprised of residential
access networks. These access networks, and their providers, are now
critical infrastructure, and significant research is devoted to
measuring residential broadband speed and reliability [SAMKNOWS].
Unfortunately, Customer Premises Equipment (CPE) is one of the
weakest links in the chain of network equipment connecting consumers
to the Internet. Customers typically do not perform proactive
maintenance, e.g., firmware updates, on their own CPE. In many
cases, CPE is even deployed with default authentication credentials,
a fact that has been exploited by various Internet-wide denial-of-
service attacks [MIRAI].
A central observation motivating this document is that customers
simply cannot be trusted to manage their own networks, much less the
path-critical CPE. Given the difficulty in maintaining the hygiene
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and resilience of broadband access, CPE maintenance should instead be
treated as a shared global responsibility among Internet Service
Providers (ISPs).
Further complicating customer management is choice in ISP, which is
currently available to nearly half of US households. While customers
may switch providers, their biographical, billing, and technological
details remain constant. Therefore, service providers need
mechanisms to ensure that transitioning customers into and out of
their network is as seamless as possible from both a technical and
billing standpoint.
Finally, service providers, advertisers, and law enforcement agencies
have varying but important reasons to track unique users' behavior on
the Internet. While RFC 7043 [RFC7043] makes use of EUI48 and EUI64
Resource Record (RR) types to uniquely identify CPE devices and
better support third-party tracking, these mechanisms can be defeated
by the customer simply purchasing new CPE.
This document takes a holistic, end-to-end view of customer
management with the aim of enhancing customer QoE and overall network
security. To enable shared CPE maintenance, this document leverages
the Domain Name System (DNS), described in RFC 1034 [RFC1034] and
RFC 1035 [RFC1035], and introduces new RR types to aid network
management.
1.1. Terminology
This document uses capitalized keywords such as MUST and MAY to
describe the requirements for using the registered RR types. The
intended meaning of those keywords in this document are the same as
those described in RFC 2119 [RFC2119] and RFC 8174 [RFC8174].
Although these keywords are often used to specify normative
requirements in IETF Standards, their use in this document does not
imply that this document is a standard of any kind.
2. Customer Management Resource Records
The ubiquity of residential broadband Internet service affords myriad
benefits to consumers, but also poses a daunting challenge for
Internet Service Providers -- how to best manage sensitive customer
identifiers and billing details, while ensuring the resilience and
security of CPE devices on their network?
This document introduces four new RRs to assist in the management of
customer data by ISPs.
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This section describes the purpose and wire format of the new DNS
RRs.
2.1. The PASSWORD Resource Record
The PASSWORD RR facilitates remote management of CPE devices by
providing the login credentials for the CPE in a single RR. These
credentials are used by authorized service providers to authenticate
to the CPE. Authenticated users can then install important software
and configuration updates to benefit the security and health of the
provider's network.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| USERNAME |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PASSWORD |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: PASSWORD RDATA Format
Where:
USERNAME
The <character-string> username of the account holder located at
the CPE. In order to limit gratuitous expressions of
individuality, usernames MUST be 16 or fewer ASCII characters and
MUST NOT include punctuation.
PASSWORD
The <character-string> password associated with the USERNAME. In
order to keep the RR size to a minimum, passwords longer than 32
bits are NOT supported.
Hosts on which multiple accounts exist SHOULD have separate PASSWORD
RRs for each account.
2.2. The CREDITCARD Resource Record
The CREDITCARD RR stores the billing details of the primary account
holder located at the hostname associated with the CPE. Upon gaining
a new subscriber, an ISP enters their billing details in a CREDITCARD
RR so that it MAY be queried as needed for automated billing
purposes. In addition, any outside entity with whom the customer
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develops a recurring payment plan MAY query this RR for payment
details as well. Storing payment information in an RR, rather than
in the databases of disparate organizations with varying data
security postures, helps reduce attack vectors available to malicious
actors seeking this data.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| CARDNUMBER |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| EXPIRE |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| CHECKSUM |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: CREDITCARD RDATA Format
Where:
CARDNUMBER
The <character-string> 16-digit credit card number used for
billing by the host's service provider. This field MUST NOT
contain punctuation or spaces; only numeric digits
represented in ASCII are allowed. Because this field is 16
digits in length, users MUST NOT use American Express cards.
EXPIRE
A <character-string> specifying the two-digit month and two-
digit year in which the credit card expires. This field MUST
NOT contain punctuation or spaces; only numeric digits
represented in ASCII are allowed.
CHECKSUM
In order to protect against bit errors occurring in the
CARDNUMBER field, this RR type MUST use error checking as
follows: Luhn's algorithm is employed as a simple checksum to
validate that none of the 16 digits were corrupted in
transit. Starting with the leftmost digit, we add this
digit's value to a running total; for every second digit
(beginning with the second-from-left digit), we add twice its
value to the running total. This algorithm continues until
all 16 digits have been exhausted. With this partial sum in
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hand, we solve for the value x such that x added to our
partial sum is congruent to 0 modulo 10, and store x in the
CHECKSUM field.
When a CREDITCARD RR is queried, the recipient simply
computes Luhn's algorithm in the same manner as described
above, and validates that their computed value of x matches
that stored in the CHECKSUM field.
Note that this novel use of Luhn's algorithm MAY have
applications outside of the CREDITCARD RR.
2.3. The SSN Resource Record
The SSN RR maps hostnames to the US Social Security number and birth
date of a user located at that host. For CPE behind which multiple
users reside, a separate SSN RR SHOULD be entered into the DNS for
each user. When residential broadband service becomes available
outside of the United States, those countries SHOULD adopt
identifiers that are compatible with the US SSN in order to ease
administrative burden on the DNS and multinational service providers.
During tax preparation season, the United States Internal Revenue
Service WILL query the SSN RR to verify residency and proof of
hostname ownership. In addition, the SSN RR MAY be used in
conjunction with the CREDITCARD RR to automate the collection of back
taxes owed.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SOCIAL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BIRTHDATE |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: SSN RDATA Format
Where:
SOCIAL
The Social Security number of the user associated with the
host, formatted as a 32-bit unsigned integer in network byte
order.
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BIRTHDATE
A 64-bit timestamp representing the number of seconds past the
Unix Epoch that the individual described by this RR was born.
Because the Unix Epoch predates the birth of all Internet
users, this field provides a sufficient range of values for
ISPs to describe their subscribers. The 64-bit timestamp field
is also "future proof", avoiding the Year 2038 problem and
ensuring SSN RR applicability into the foreseeable future.
2.4. The SSNPTR Resource Record
The SSNPTR RR provides the reverse functionality of the SSN RR; it
maps Social Security numbers to hostnames. Every individual for whom
an ISP provides service, not only primary account holders, SHOULD
have an SSNPTR RR entry in the DNS.
One benefit provided by the SSNPTR RR is the ability to conduct some
population census functions remotely. For example, consider a
residential ISP with SSNPTR RRs for each of its subscribers.
Performing SSNPTR queries for all of their SSNs returns the host at
which those individuals are located, allowing for the trivial
association of family members behind the same CPE device. Further,
these hosts can then be geolocated using an IP geolocation service or
LOC RR [RFC1876], providing the ability to determine municipal
populations and thereby inform decisions about appropriations and
appropriate public policies.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ DNAME /
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: SSNPTR RDATA Format
Where:
DNAME A <domain-name> that points to a location in the domain name
space.
3. Related RR Types
The practice of introducing new RR types to the DNS to support
functionality that is either only tangentially related or wholly
unrelated to name resolution is well established.
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[RFC2539] describes the Diffie-Hellman KEY RR type, which is used to
conveniently store public key parameters for a domain. The SRV RR
type [RFC2782] combines name resolution with transport- and
application-layer details, providing a "no-fuss" way for network
administrators to advertise the location of specific services. The
Name Authority PTR (NAPTR) RR [RFC2915] recognized and corrected the
lack of POSIX Extended Regular Expression support in the DNS,
allowing for DNS-based automobile parts identification systems
[RFC3402] among other use cases. Having established the DNS's role
in encryption in [RFC2539], the IPSECKEY RR resurrected the since-
obsoleted ability to store public key parameters for the purposes of
IPsec encryption [RFC4025]. [RFC4255] codified the natural inter-
dependency between the Secure Shell (SSH) protocol [RFC4253] and DNS
by providing the SSHFP RR type, which is used to verify the host key
of a server.
Extending the idea of distributing public key parameters via DNS,
[RFC4398] introduced the CERT RR type to publish X.509 and PGP
certificates. [RFC4701] introduces the DHCID RR type to solve the
problem of Fully Qualified Domain Name (FQDN) collisions when Dynamic
Host Configuration Protocol (DHCP) clients make DNS updates after
obtaining a DHCP lease. The TLSA RR type [RFC6698] is used to
associate a TLS certificate with a domain, leveraging DNSSEC as the
binding, and the CAA RR type [RFC6844] specifies the Certificate
Authority allowed to issue certificates for a domain. The EUI48 and
EUI64 RR types specified in [RFC7043] seek to eliminate boundaries in
the TCP/IP model by creating, in essence, A records for MAC
addresses.
4. IANA Considerations
This document has no IANA actions.
5. Security Considerations
DNSSEC [RFC4033] SHOULD be used in conjunction with the PASSWORD,
CREDITCARD, SSN, and SSNPTR RR types to provide data integrity.
Employing DNSSEC ensures that the data contained in these RRs
originates from an authoritative source and is not, for example, an
attacker attempting to provide invalid login credentials in response
to a legitimate request for a PASSWORD RR.
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6. References
6.1. 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>.
[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>.
6.2. Informative References
[CAMEL] Hubert, B., "The DNS Camel", March 2018,
<https://blog.powerdns.com/2018/03/22/
the-dns-camel-or-the-rise-in-dns-complexit/>.
[MIRAI] Antonakakis, M., April, T., Bailey, M., Bernhard, M.,
Bursztein, E., Cochran, J., Durumeric, Z., Halderman, J.,
Invernizzi, L., Kallitsis, M., Kumar, D., Lever, C., Ma,
Z., Mason, J., Menscher, D., Seaman, C., Sullivan, N.,
Thomas, K., and Y. Zhou, "Understanding the Mirai Botnet",
Proceedings of the 26th USENIX Security Symposium, August
2017, <https://www.usenix.org/system/files/conference/
usenixsecurity17/sec17-antonakakis.pdf>.
[RFC1034] Mockapetris, P., "Domain names - concepts and facilities",
STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987,
<https://www.rfc-editor.org/info/rfc1034>.
[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>.
[RFC1876] Davis, C., Vixie, P., Goodwin, T., and I. Dickinson, "A
Means for Expressing Location Information in the Domain
Name System", RFC 1876, DOI 10.17487/RFC1876, January
1996, <https://www.rfc-editor.org/info/rfc1876>.
[RFC2539] Eastlake 3rd, D., "Storage of Diffie-Hellman Keys in the
Domain Name System (DNS)", RFC 2539, DOI 10.17487/RFC2539,
March 1999, <https://www.rfc-editor.org/info/rfc2539>.
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RFC 8567 Customer Management over DNS 1 April 2019
[RFC2782] Gulbrandsen, A., Vixie, P., and L. Esibov, "A DNS RR for
specifying the location of services (DNS SRV)", RFC 2782,
DOI 10.17487/RFC2782, February 2000,
<https://www.rfc-editor.org/info/rfc2782>.
[RFC2915] Mealling, M. and R. Daniel, "The Naming Authority Pointer
(NAPTR) DNS Resource Record", RFC 2915,
DOI 10.17487/RFC2915, September 2000,
<https://www.rfc-editor.org/info/rfc2915>.
[RFC3402] Mealling, M., "Dynamic Delegation Discovery System (DDDS)
Part Two: The Algorithm", RFC 3402, DOI 10.17487/RFC3402,
October 2002, <https://www.rfc-editor.org/info/rfc3402>.
[RFC4025] Richardson, M., "A Method for Storing IPsec Keying
Material in DNS", RFC 4025, DOI 10.17487/RFC4025, March
2005, <https://www.rfc-editor.org/info/rfc4025>.
[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>.
[RFC4253] Ylonen, T. and C. Lonvick, Ed., "The Secure Shell (SSH)
Transport Layer Protocol", RFC 4253, DOI 10.17487/RFC4253,
January 2006, <https://www.rfc-editor.org/info/rfc4253>.
[RFC4255] Schlyter, J. and W. Griffin, "Using DNS to Securely
Publish Secure Shell (SSH) Key Fingerprints", RFC 4255,
DOI 10.17487/RFC4255, January 2006,
<https://www.rfc-editor.org/info/rfc4255>.
[RFC4398] Josefsson, S., "Storing Certificates in the Domain Name
System (DNS)", RFC 4398, DOI 10.17487/RFC4398, March 2006,
<https://www.rfc-editor.org/info/rfc4398>.
[RFC4701] Stapp, M., Lemon, T., and A. Gustafsson, "A DNS Resource
Record (RR) for Encoding Dynamic Host Configuration
Protocol (DHCP) Information (DHCID RR)", RFC 4701,
DOI 10.17487/RFC4701, October 2006,
<https://www.rfc-editor.org/info/rfc4701>.
[RFC6698] Hoffman, P. and J. Schlyter, "The DNS-Based Authentication
of Named Entities (DANE) Transport Layer Security (TLS)
Protocol: TLSA", RFC 6698, DOI 10.17487/RFC6698, August
2012, <https://www.rfc-editor.org/info/rfc6698>.
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[RFC6844] Hallam-Baker, P. and R. Stradling, "DNS Certification
Authority Authorization (CAA) Resource Record", RFC 6844,
DOI 10.17487/RFC6844, January 2013,
<https://www.rfc-editor.org/info/rfc6844>.
[RFC7043] Abley, J., "Resource Records for EUI-48 and EUI-64
Addresses in the DNS", RFC 7043, DOI 10.17487/RFC7043,
October 2013, <https://www.rfc-editor.org/info/rfc7043>.
[SAMKNOWS]
Crawford, S., "SamKnows: The Internet Measurement
Standard", <https://samknows.com/>.
Acknowledgements
We thank the US Federal Communications Commission for the repeal of
network neutrality legislation, allowing ISPs to provide their
customers with the level and type of service that ISPs have come to
expect.
We also thank Bert Hubert for identifying the dearth of DNS RR
standards in his blog post and IETF lecture entitled The DNS Camel
[CAMEL], so named for the drought of DNS-enabled functionality of the
last several decades.
Authors' Addresses
Erik C. Rye
CMAND
1 University Circle
Monterey, CA 93943
United States of America
Email: rye@cmand.org
Robert Beverly
CMAND
1 University Circle
Monterey, CA 93943
United States of America
Email: rbeverly@cmand.org
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