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diff --git a/doc/draft/draft-ietf-dnsext-dhcid-rr-12.txt b/doc/draft/draft-ietf-dnsext-dhcid-rr-12.txt deleted file mode 100644 index 07749d954947..000000000000 --- a/doc/draft/draft-ietf-dnsext-dhcid-rr-12.txt +++ /dev/null @@ -1,674 +0,0 @@ - - - - -DNSEXT M. Stapp -Internet-Draft Cisco Systems, Inc. -Expires: September 1, 2006 T. Lemon - Nominum, Inc. - A. Gustafsson - Araneus Information Systems Oy - February 28, 2006 - - - A DNS RR for Encoding DHCP Information (DHCID RR) - <draft-ietf-dnsext-dhcid-rr-12.txt> - -Status of this Memo - - By submitting this Internet-Draft, each author represents that any - applicable patent or other IPR claims of which he or she is aware - have been or will be disclosed, and any of which he or she becomes - aware will be disclosed, in accordance with Section 6 of BCP 79. - - Internet-Drafts are working documents of the Internet Engineering - Task Force (IETF), its areas, and its working groups. Note that - other groups may also distribute working documents as Internet- - Drafts. - - Internet-Drafts are draft documents valid for a maximum of six months - and may be updated, replaced, or obsoleted by other documents at any - time. It is inappropriate to use Internet-Drafts as reference - material or to cite them other than as "work in progress." - - The list of current Internet-Drafts can be accessed at - http://www.ietf.org/ietf/1id-abstracts.txt. - - The list of Internet-Draft Shadow Directories can be accessed at - http://www.ietf.org/shadow.html. - - This Internet-Draft will expire on September 1, 2006. - -Copyright Notice - - Copyright (C) The Internet Society (2006). - -Abstract - - It is possible for DHCP clients to attempt to update the same DNS - FQDN or attempt to update a DNS FQDN that has been added to the DNS - for another purpose as they obtain DHCP leases. Whether the DHCP - server or the clients themselves perform the DNS updates, conflicts - can arise. To resolve such conflicts, "Resolution of DNS Name - - - -Stapp, et al. Expires September 1, 2006 [Page 1] - -Internet-Draft The DHCID RR February 2006 - - - Conflicts" [1] proposes storing client identifiers in the DNS to - unambiguously associate domain names with the DHCP clients to which - they refer. This memo defines a distinct RR type for this purpose - for use by DHCP clients and servers, the "DHCID" RR. - - -Table of Contents - - 1. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 3. The DHCID RR . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 3.1. DHCID RDATA format . . . . . . . . . . . . . . . . . . . . 3 - 3.2. DHCID Presentation Format . . . . . . . . . . . . . . . . 4 - 3.3. The DHCID RR Identifier Type Codes . . . . . . . . . . . . 4 - 3.4. The DHCID RR Digest Type Code . . . . . . . . . . . . . . 4 - 3.5. Computation of the RDATA . . . . . . . . . . . . . . . . . 5 - 3.5.1. Using the Client's DUID . . . . . . . . . . . . . . . 5 - 3.5.2. Using the Client Identifier Option . . . . . . . . . . 5 - 3.5.3. Using the Client's htype and chaddr . . . . . . . . . 6 - 3.6. Examples . . . . . . . . . . . . . . . . . . . . . . . . . 6 - 3.6.1. Example 1 . . . . . . . . . . . . . . . . . . . . . . 6 - 3.6.2. Example 2 . . . . . . . . . . . . . . . . . . . . . . 6 - 3.6.3. Example 3 . . . . . . . . . . . . . . . . . . . . . . 7 - 4. Use of the DHCID RR . . . . . . . . . . . . . . . . . . . . . 7 - 5. Updater Behavior . . . . . . . . . . . . . . . . . . . . . . . 8 - 6. Security Considerations . . . . . . . . . . . . . . . . . . . 8 - 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 - 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 9 - 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 9 - 9.1. Normative References . . . . . . . . . . . . . . . . . . . 9 - 9.2. Informative References . . . . . . . . . . . . . . . . . . 10 - Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 11 - Intellectual Property and Copyright Statements . . . . . . . . . . 12 - - - - - - - - - - - - - - - - - - -Stapp, et al. Expires September 1, 2006 [Page 2] - -Internet-Draft The DHCID RR February 2006 - - -1. Terminology - - 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 [2]. - - -2. Introduction - - A set of procedures to allow DHCP [6] [10] clients and servers to - automatically update the DNS (RFC 1034 [3], RFC 1035 [4]) is proposed - in "Resolution of DNS Name Conflicts" [1]. - - Conflicts can arise if multiple DHCP clients wish to use the same DNS - name or a DHCP client attempts to use a name added for another - purpose. To resolve such conflicts, "Resolution of DNS Name - Conflicts" [1] proposes storing client identifiers in the DNS to - unambiguously associate domain names with the DHCP clients using - them. In the interest of clarity, it is preferable for this DHCP - information to use a distinct RR type. This memo defines a distinct - RR for this purpose for use by DHCP clients or servers, the "DHCID" - RR. - - In order to obscure potentially sensitive client identifying - information, the data stored is the result of a one-way SHA-256 hash - computation. The hash includes information from the DHCP client's - message as well as the domain name itself, so that the data stored in - the DHCID RR will be dependent on both the client identification used - in the DHCP protocol interaction and the domain name. This means - that the DHCID RDATA will vary if a single client is associated over - time with more than one name. This makes it difficult to 'track' a - client as it is associated with various domain names. - - -3. The DHCID RR - - The DHCID RR is defined with mnemonic DHCID and type code [TBD]. The - DHCID RR is only defined in the IN class. DHCID RRs cause no - additional section processing. The DHCID RR is not a singleton type. - -3.1. DHCID RDATA format - - The RDATA section of a DHCID RR in transmission contains RDLENGTH - octets of binary data. The format of this data and its - interpretation by DHCP servers and clients are described below. - - DNS software should consider the RDATA section to be opaque. DHCP - clients or servers use the DHCID RR to associate a DHCP client's - - - -Stapp, et al. Expires September 1, 2006 [Page 3] - -Internet-Draft The DHCID RR February 2006 - - - identity with a DNS name, so that multiple DHCP clients and servers - may deterministically perform dynamic DNS updates to the same zone. - From the updater's perspective, the DHCID resource record RDATA - consists of a 2-octet identifier type, in network byte order, - followed by a 1-octet digest type, followed by one or more octets - representing the actual identifier: - - < 2 octets > Identifier type code - < 1 octet > Digest type code - < n octets > Digest (length depends on digest type) - -3.2. DHCID Presentation Format - - In DNS master files, the RDATA is represented as a single block in - base 64 encoding identical to that used for representing binary data - in RFC 3548 [7]. The data may be divided up into any number of white - space separated substrings, down to single base 64 digits, which are - concatenated to form the complete RDATA. These substrings can span - lines using the standard parentheses. - -3.3. The DHCID RR Identifier Type Codes - - The DHCID RR Identifier Type Code specifies what data from the DHCP - client's request was used as input into the hash function. The - identifier type codes are defined in a registry maintained by IANA, - as specified in Section 7. The initial list of assigned values for - the identifier type code is: - - 0x0000 = htype, chaddr from a DHCPv4 client's DHCPREQUEST [6]. - 0x0001 = The data octets (i.e., the Type and Client-Identifier - fields) from a DHCPv4 client's Client Identifier option [9]. - 0x0002 = The client's DUID (i.e., the data octets of a DHCPv6 - client's Client Identifier option [10] or the DUID field from a - DHCPv4 client's Client Identifier option [12]). - - 0x0003 - 0xfffe = Available to be assigned by IANA. - - 0xffff = RESERVED - -3.4. The DHCID RR Digest Type Code - - The DHCID RR Digest Type Code is an identifier for the digest - algorithm used. The digest is calculated over an identifier and the - canonical FQDN as described in the next section. - - The digest type codes are defined in a registry maintained by IANA, - as specified in Section 7. The initial list of assigned values for - the digest type codes is: value 0 is reserved and value 1 is SHA-256. - - - -Stapp, et al. Expires September 1, 2006 [Page 4] - -Internet-Draft The DHCID RR February 2006 - - - Reserving other types requires IETF standards action. Defining new - values will also require IETF standards action to document how DNS - updaters are to deal with multiple digest types. - -3.5. Computation of the RDATA - - The DHCID RDATA is formed by concatenating the 2-octet identifier - type code with variable-length data. - - The RDATA for all type codes other than 0xffff, which is reserved for - future expansion, is formed by concatenating the 2-octet identifier - type code, the 1-octet digest type code, and the digest value (32 - octets for SHA-256). - - < identifier-type > < digest-type > < digest > - - The input to the digest hash function is defined to be: - - digest = SHA-256(< identifier > < FQDN >) - - The FQDN is represented in the buffer in unambiguous canonical form - as described in RFC 4034 [8], section 6.1. The identifier type code - and the identifier are related as specified in Section 3.3: the - identifier type code describes the source of the identifier. - - A DHCPv4 updater uses the 0x0002 type code if a Client Identifier - option is present in the DHCPv4 messages and it is encoded as - specified in [12]. Otherwise, the updater uses 0x0001 if a Client - Identifier option is present and 0x0000 if not. - - A DHCPv6 updater always uses the 0x0002 type code. - -3.5.1. Using the Client's DUID - - When the updater is using the Client's DUID (either from a DHCPv6 - Client Identifier option or from a portion of the DHCPv4 Client - Identifier option encoded as specified in [12]), the first two octets - of the DHCID RR MUST be 0x0002, in network byte order. The third - octet is the digest type code (1 for SHA-256). The rest of the DHCID - RR MUST contain the results of computing the SHA-256 hash across the - octets of the DUID followed by the FQDN. - -3.5.2. Using the Client Identifier Option - - When the updater is using the DHCPv4 Client Identifier option sent by - the client in its DHCPREQUEST message, the first two octets of the - DHCID RR MUST be 0x0001, in network byte order. The third octet is - the digest type code (1 for SHA-256). The rest of the DHCID RR MUST - - - -Stapp, et al. Expires September 1, 2006 [Page 5] - -Internet-Draft The DHCID RR February 2006 - - - contain the results of computing the SHA-256 hash across the data - octets (i.e., the Type and Client-Identifier fields) of the option, - followed by the FQDN. - -3.5.3. Using the Client's htype and chaddr - - When the updater is using the client's link-layer address as the - identifier, the first two octets of the DHCID RDATA MUST be zero. - The third octet is the digest type code (1 for SHA-256). To generate - the rest of the resource record, the updater computes a one-way hash - using the SHA-256 algorithm across a buffer containing the client's - network hardware type, link-layer address, and the FQDN data. - Specifically, the first octet of the buffer contains the network - hardware type as it appeared in the DHCP 'htype' field of the - client's DHCPREQUEST message. All of the significant octets of the - 'chaddr' field in the client's DHCPREQUEST message follow, in the - same order in which the octets appear in the DHCPREQUEST message. - The number of significant octets in the 'chaddr' field is specified - in the 'hlen' field of the DHCPREQUEST message. The FQDN data, as - specified above, follows. - -3.6. Examples - -3.6.1. Example 1 - - A DHCP server allocating the IPv4 address 10.0.0.1 to a client with - Ethernet MAC address 01:02:03:04:05:06 using domain name - "client.example.com" uses the client's link-layer address to identify - the client. The DHCID RDATA is composed by setting the two type - octets to zero, the 1-octet digest type to 1 for SHA-256, and - performing an SHA-256 hash computation across a buffer containing the - Ethernet MAC type octet, 0x01, the six octets of MAC address, and the - domain name (represented as specified in Section 3.5). - - client.example.com. A 10.0.0.1 - client.example.com. DHCID ( AAABxLmlskllE0MVjd57zHcWmEH3pCQ6V - ytcKD//7es/deY= ) - - If the DHCID RR type is not supported, the RDATA would be encoded - [13] as: - - \# 35 ( 000001c4b9a5b249651343158dde7bcc77169841f7a4243a572b5c283 - fffedeb3f75e6 ) - -3.6.2. Example 2 - - A DHCP server allocates the IPv4 address 10.0.12.99 to a client which - included the DHCP client-identifier option data 01:07:08:09:0a:0b:0c - - - -Stapp, et al. Expires September 1, 2006 [Page 6] - -Internet-Draft The DHCID RR February 2006 - - - in its DHCP request. The server updates the name "chi.example.com" - on the client's behalf, and uses the DHCP client identifier option - data as input in forming a DHCID RR. The DHCID RDATA is formed by - setting the two type octets to the value 0x0001, the 1-octet digest - type to 1 for SHA-256, and performing a SHA-256 hash computation - across a buffer containing the seven octets from the client-id option - and the FQDN (represented as specified in Section 3.5). - - chi.example.com. A 10.0.12.99 - chi.example.com. DHCID ( AAEBOSD+XR3Os/0LozeXVqcNc7FwCfQdW - L3b/NaiUDlW2No= ) - - If the DHCID RR type is not supported, the RDATA would be encoded - [13] as: - - \# 35 ( 0001013920fe5d1dceb3fd0ba3379756a70d73b17009f41d58bddbfcd - 6a2503956d8da ) - -3.6.3. Example 3 - - A DHCP server allocates the IPv6 address 2000::1234:5678 to a client - which included the DHCPv6 client-identifier option data 00:01:00:06: - 41:2d:f1:66:01:02:03:04:05:06 in its DHCPv6 request. The server - updates the name "chi6.example.com" on the client's behalf, and uses - the DHCP client identifier option data as input in forming a DHCID - RR. The DHCID RDATA is formed by setting the two type octets to the - value 0x0002, the 1-octet digest type to 1 for SHA-256, and - performing a SHA-256 hash computation across a buffer containing the - 14 octets from the client-id option and the FQDN (represented as - specified in Section 3.5). - - chi6.example.com. AAAA 2000::1234:5678 - chi6.example.com. DHCID ( AAIBY2/AuCccgoJbsaxcQc9TUapptP69l - OjxfNuVAA2kjEA= ) - - If the DHCID RR type is not supported, the RDATA would be encoded - [13] as: - - \# 35 ( 000201636fc0b8271c82825bb1ac5c41cf5351aa69b4febd94e8f17cd - b95000da48c40 ) - - -4. Use of the DHCID RR - - This RR MUST NOT be used for any purpose other than that detailed in - "Resolution of DNS Name Conflicts" [1]. Although this RR contains - data that is opaque to DNS servers, the data must be consistent - across all entities that update and interpret this record. - - - -Stapp, et al. Expires September 1, 2006 [Page 7] - -Internet-Draft The DHCID RR February 2006 - - - Therefore, new data formats may only be defined through actions of - the DHC Working Group, as a result of revising [1]. - - -5. Updater Behavior - - The data in the DHCID RR allows updaters to determine whether more - than one DHCP client desires to use a particular FQDN. This allows - site administrators to establish policy about DNS updates. The DHCID - RR does not establish any policy itself. - - Updaters use data from a DHCP client's request and the domain name - that the client desires to use to compute a client identity hash, and - then compare that hash to the data in any DHCID RRs on the name that - they wish to associate with the client's IP address. If an updater - discovers DHCID RRs whose RDATA does not match the client identity - that they have computed, the updater SHOULD conclude that a different - client is currently associated with the name in question. The - updater SHOULD then proceed according to the site's administrative - policy. That policy might dictate that a different name be selected, - or it might permit the updater to continue. - - -6. Security Considerations - - The DHCID record as such does not introduce any new security problems - into the DNS. In order to obscure the client's identity information, - a one-way hash is used. And, in order to make it difficult to - 'track' a client by examining the names associated with a particular - hash value, the FQDN is included in the hash computation. Thus, the - RDATA is dependent on both the DHCP client identification data and on - each FQDN associated with the client. - - However, it should be noted that an attacker that has some knowledge, - such as of MAC addresses commonly used in DHCP client identification - data, may be able to discover the client's DHCP identify by using a - brute-force attack. Even without any additional knowledge, the - number of unknown bits used in computing the hash is typically only - 48 to 80. - - Administrators should be wary of permitting unsecured DNS updates to - zones, whether or not they are exposed to the global Internet. Both - DHCP clients and servers SHOULD use some form of update - authentication (e.g., TSIG [11]) when performing DNS updates. - - -7. IANA Considerations - - - - -Stapp, et al. Expires September 1, 2006 [Page 8] - -Internet-Draft The DHCID RR February 2006 - - - IANA is requested to allocate a DNS RR type number for the DHCID - record type. - - This specification defines a new number-space for the 2-octet - identifier type codes associated with the DHCID RR. IANA is - requested to establish a registry of the values for this number- - space. Three initial values are assigned in Section 3.3, and the - value 0xFFFF is reserved for future use. New DHCID RR identifier - type codes are assigned through Standards Action, as defined in RFC - 2434 [5]. - - This specification defines a new number-space for the 1-octet digest - type codes associated with the DHCID RR. IANA is requested to - establish a registry of the values for this number-space. Two - initial values are assigned in Section 3.4. New DHCID RR digest type - codes are assigned through Standards Action, as defined in RFC 2434 - [5]. - - -8. Acknowledgements - - Many thanks to Harald Alvestrand, Ralph Droms, Olafur Gudmundsson, - Sam Hartman, Josh Littlefield, Pekka Savola, and especially Bernie - Volz for their review and suggestions. - - -9. References - -9.1. Normative References - - [1] Stapp, M. and B. Volz, "Resolution of DNS Name Conflicts Among - DHCP Clients (draft-ietf-dhc-dns-resolution-*)", February 2006. - - [2] Bradner, S., "Key words for use in RFCs to Indicate Requirement - Levels", BCP 14, RFC 2119, March 1997. - - [3] Mockapetris, P., "Domain names - concepts and facilities", - STD 13, RFC 1034, November 1987. - - [4] Mockapetris, P., "Domain names - implementation and - specification", STD 13, RFC 1035, November 1987. - - [5] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA - Considerations Section in RFCs", BCP 26, RFC 2434, October 1998. - - - - - - - -Stapp, et al. Expires September 1, 2006 [Page 9] - -Internet-Draft The DHCID RR February 2006 - - -9.2. Informative References - - [6] Droms, R., "Dynamic Host Configuration Protocol", RFC 2131, - March 1997. - - [7] Josefsson, S., "The Base16, Base32, and Base64 Data Encodings", - RFC 3548, July 2003. - - [8] Arends, R., Austein, R., Larson, M., Massey, D., and S. Rose, - "Resource Records for the DNS Security Extensions", RFC 4034, - March 2005. - - [9] Alexander, S. and R. Droms, "DHCP Options and BOOTP Vendor - Extensions", RFC 2132, March 1997. - - [10] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., and M. - Carney, "Dynamic Host Configuration Protocol for IPv6 - (DHCPv6)", RFC 3315, July 2003. - - [11] Vixie, P., Gudmundsson, O., Eastlake, D., and B. Wellington, - "Secret Key Transaction Authentication for DNS (TSIG)", - RFC 2845, May 2000. - - [12] Lemon, T. and B. Sommerfeld, "Node-specific Client Identifiers - for Dynamic Host Configuration Protocol Version Four (DHCPv4)", - RFC 4361, February 2006. - - [13] Gustafsson, A., "Handling of Unknown DNS Resource Record (RR) - Types", RFC 3597, September 2003. - - - - - - - - - - - - - - - - - - - - - - -Stapp, et al. Expires September 1, 2006 [Page 10] - -Internet-Draft The DHCID RR February 2006 - - -Authors' Addresses - - Mark Stapp - Cisco Systems, Inc. - 1414 Massachusetts Ave. - Boxborough, MA 01719 - USA - - Phone: 978.936.1535 - Email: mjs@cisco.com - - - Ted Lemon - Nominum, Inc. - 950 Charter St. - Redwood City, CA 94063 - USA - - Email: mellon@nominum.com - - - Andreas Gustafsson - Araneus Information Systems Oy - Ulappakatu 1 - 02320 Espoo - Finland - - Email: gson@araneus.fi - - - - - - - - - - - - - - - - - - - - - - - -Stapp, et al. Expires September 1, 2006 [Page 11] - -Internet-Draft The DHCID RR February 2006 - - -Intellectual Property Statement - - The IETF takes no position regarding the validity or scope of any - Intellectual Property Rights or other rights that might be claimed to - pertain to the implementation or use of the technology described in - this document or the extent to which any license under such rights - might or might not be available; nor does it represent that it has - made any independent effort to identify any such rights. 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