DHC B. Volz Internet-Draft Cisco Systems, Inc. Intended status: Standards Track August 3, 2009 Expires: February 4, 2010 DHCPv4 Vendor-specific Message Status of this Memo This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and 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 February 4, 2010. Copyright Notice Copyright (c) 2009 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 in effect on the date of publication of this document (http://trustee.ietf.org/license-info). Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Abstract This document requests a vendor-specific DHCPv4 message assignment. This message can be used for vendor specific and experimental purposes. Volz Expires February 4, 2010 [Page 1] Internet-Draft DHCPv4 Vendor-specific Message August 2009 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Vendor-specific Message . . . . . . . . . . . . . . . . . . . . 3 4. Vendor Message Option . . . . . . . . . . . . . . . . . . . . . 4 5. Security Considerations . . . . . . . . . . . . . . . . . . . . 5 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6 7.1. Normative References . . . . . . . . . . . . . . . . . . . 6 7.2. Informative References . . . . . . . . . . . . . . . . . . 6 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 7 Volz Expires February 4, 2010 [Page 2] Internet-Draft DHCPv4 Vendor-specific Message August 2009 1. Introduction DHCPv4 [RFC2131] specifies a mechanism for the assignment of addresses and configuration information to nodes. The protocol provides for 256 possible message codes, of which a small number are assigned ([DHCPv4Params]). Each of the assigned message codes have specific purposes. New message codes are assigned through IETF Standards Action. There may be a need for vendors of DHCPv4 clients, relay agents, or servers to experiment with new capabilities that require new messages to be exchanged between these elements. Thus, this document defines the format for and requests that a new message code be reserved for vendor-specific and experimental purposes. 2. 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 [RFC2119]. 3. Vendor-specific Message The vendor-specific message may be exchanged between clients, relay agents, and/or servers and allows multiple vendors to make use of the message for completely different and independent purposes. Clients and servers MAY chose to support this message; those that do not, MUST discard the message. Relay agents SHOULD relay these messages as they would other DHCPv4 messages unless the relay agent understands the specific message and knows that the message was directed at it. Applications using these messages MUST NOT assume that all DHCPv4 clients, relay agents, and servers support them and MUST use good networking practices when transmitting and retransmitting these messages. For some applications, it may be appropriate to use Vendor-Identifying Vendor Options [RFC3925] in a standard DHCPv4 exchange to negotiate whether the end-points support the vendor- specific message. A vendor-specifc message is constructed by placing the Vendor- Specific Message number (254) into the DHCP Message Type option [RFC2132] and including the Vendor Message Option defined below. A Vendor-Specific Message that does not contain the Vendor Message Option MUST be ignored. A Vendor Message Option in a DHCPv4 message Volz Expires February 4, 2010 [Page 3] Internet-Draft DHCPv4 Vendor-specific Message August 2009 other than the Vendor-Specific Message MUST be ignored. 4. Vendor Message Option The Vendor Message Option serves three purposes. It specifies the Enterprise Number to identify the vendor, it specifies the vendor's message type, and optionally contains vendor options related to the message. The format of the Vendor Message Option is shown below: 1 1 1 1 1 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | option-code | option-len | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | + enterprise-number + | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | vendor | | | msg-type | | +-+-+-+-+-+-+-+-+ | / option-data / ~ ... ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ option-code OPTION_VENDOR_MESSAGE (TBD) option-len 5 plus the length of the vendor-option-data. enterprise-number The vendor's 32-bit Enterprise Number as registered with [EID], in network octet order. vendor-msg-type The vendor's message-type. The values are defined by the vendor identified in the enterprise-number field and are not managed by IANA. option-data Vendor specific data (of length option-len minus 5 octets). This is optional. The option-data field MUST be encoded as a sequence of code/length/ value fields of identical format to the DHCP options field and is identical to the option-data field of Vendor-Identifying Vendor Options [RFC3925]. The option codes are defined by the vendor Volz Expires February 4, 2010 [Page 4] Internet-Draft DHCPv4 Vendor-specific Message August 2009 identified in the enterprise-number field and are not managed by IANA. Option codes 0 and 255 have no pre-defined interpretation or format. Each of the encapsulated options is formatted as follows: 1 1 1 1 1 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | subopt-code | subopt-len | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / sub-option-data / ~ ... ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ subopt-code The code for the encapsulated option. subopt-len An unsigned integer giving the length of the option-data field in this encapsulated option in octets. sub-option-data Data area for the encapsulated option. Clients, relay agents, and/or servers supporting the Vendor Message Option MUST support [RFC3396]. Note: Vendor-Identifying Vendor Options [RFC3925] are not used to convey the vendor identification (enterprise-number) for the vendor- specific message as the message may contain instances of those options for other reasons. 5. Security Considerations The Security Considerations of [RFC2131] apply. This new message does potentially open up new avenues of attacking clients, relay agents, or servers. The exact nature of these attacks will depend on what functions and capabilities the message exposes and are thus not possible to describe in this document. Clients and servers that have no use for these messages SHOULD discard them and thus the threat is no different than before this message was assigned. Vendors using this new message should use the DHCPv4 security mechanisms (such as [RFC3118] as appropriate) and carefully consider the security implications of the functions and capabilities exposed. Volz Expires February 4, 2010 [Page 5] Internet-Draft DHCPv4 Vendor-specific Message August 2009 6. IANA Considerations IANA is requested to assign DHCPv4 Message type 254 to the Vendor- specific Message in the registry maintained in [DHCPv4Params]: 254 VENDOR-SPECIFIC IANA is requested to assign a DHCPv4 option number to the Vendor Message Option in the registry maintained in [DHCPv4Params]: TBD OPTION_VENDOR_MESSAGE 7. References 7.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2131] Droms, R., "Dynamic Host Configuration Protocol", RFC 2131, March 1997. [EID] IANA, "Private Enterprise Numbers. http://www.iana.org/assignments/enterprise-numbers". 7.2. Informative References [RFC2132] Alexander, S. and R. Droms, "DHCP Options and BOOTP Vendor Extensions", RFC 2132, March 1997. [RFC3118] Droms, R. and W. Arbaugh, "Authentication for DHCP Messages", RFC 3118, June 2001. [RFC3396] Lemon, T. and S. Cheshire, "Encoding Long Options in the Dynamic Host Configuration Protocol (DHCPv4)", RFC 3396, November 2002. [RFC3925] Littlefield, J., "Vendor-Identifying Vendor Options for Dynamic Host Configuration Protocol version 4 (DHCPv4)", RFC 3925, October 2004. [DHCPv4Params] IANA, "Dynamic Host Configuration Protocol (DHCP) and Bootstrap Protocol (BOOTP) Parameters. http://www.iana.org/assignments/bootp-dhcp-parameters". Volz Expires February 4, 2010 [Page 6] Internet-Draft DHCPv4 Vendor-specific Message August 2009 Author's Address Bernard Volz Cisco Systems, Inc. 1414 Massachusetts Ave. Boxborough, MA 01719 USA Phone: +1 978 936 0000 Email: volz@cisco.com Volz Expires February 4, 2010 [Page 7]