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.
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
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.
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
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
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.
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.
[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.
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>.
[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>.
[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: firstname.lastname@example.org Robert Beverly CMAND 1 University Circle Monterey, CA 93943 United States of America Email: email@example.com