draft-ietf-dhc-forcerenew-nonce-00.txt		draft-ietf-dhc-forcerenew-nonce-01.txt
	DHC WG D. Miles		softwire D. Miles
	Internet-Draft Alcatel-Lucent		Internet-Draft Alcatel-Lucent
	Intended status: Standards Track W. Dec		Intended status: Standards Track W. Dec
	Expires: December 5, 2009 Cisco Systems		Expires: September 11, 2011 Cisco Systems
	J. Bristow		J. Bristow
	Swisscom Schweiz AG		Swisscom Schweiz AG
	R. Maglione		R. Maglione
	Telecom Italia		Telecom Italia
	June 3, 2009		March 10, 2011
	Forcerenew Nonce Authentication		Forcerenew Nonce Authentication
	draft-ietf-dhc-forcerenew-nonce-00		draft-ietf-dhc-forcerenew-nonce-01
			Abstract
			DHCP Forcerenew allows for the reconfiguration of a single host by
			forcing the DHCP client into a Renew state on a trigger from the DHCP
			server. In Forcerenew Nonce Authentication the server exchanges a
			nonce with the client on the initial DHCP ACK that is used for
			subsequent validation of a Forcerenew message.
	Status of this Memo		Status of this Memo
	This Internet-Draft is submitted to IETF in full conformance with the		This Internet-Draft is submitted in full conformance with the
	provisions of BCP 78 and BCP 79.		provisions of BCP 78 and BCP 79.
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	Copyright Notice		Copyright Notice
	Copyright (c) 2009 IETF Trust and the persons identified as the		Copyright (c) 2011 IETF Trust and the persons identified as the
	document authors. All rights reserved.		document authors. All rights reserved.
	This document is subject to BCP 78 and the IETF Trust's Legal		This document is subject to BCP 78 and the IETF Trust's Legal
	Provisions Relating to IETF Documents in effect on the date of		Provisions Relating to IETF Documents
	publication of this document (http://trustee.ietf.org/license-info).		(http://trustee.ietf.org/license-info) in effect on the date of
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	and restrictions with respect to this document.		carefully, as they describe your rights and restrictions with respect
			to this document. Code Components extracted from this document must
	Abstract		include Simplified BSD License text as described in Section 4.e of
			the Trust Legal Provisions and are provided without warranty as
			described in the Simplified BSD License.
	DHCP Forcerenew allows for the reconfiguration of a single host by		This document may contain material from IETF Documents or IETF
	forcing the DHCP client into a Renew state on a trigger from the DHCP		Contributions published or made publicly available before November
	server. In Forcerenew Nonce Authentication the server exchanges a		10, 2008. The person(s) controlling the copyright in some of this
	nonce with the client on the initial DHCP ACK that is used for		material may not have granted the IETF Trust the right to allow
	subsequent validation of a Forcerenew message.		modifications of such material outside the IETF Standards Process.
			Without obtaining an adequate license from the person(s) controlling
			the copyright in such materials, this document may not be modified
			outside the IETF Standards Process, and derivative works of it may
			not be created outside the IETF Standards Process, except to format
			it for publication as an RFC or to translate it into languages other
			than English.
	Table of Contents		Table of Contents
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
	1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3		2. Requirements Language . . . . . . . . . . . . . . . . . . . . 4
	2. Message authentication . . . . . . . . . . . . . . . . . . . . 3		3. Message authentication . . . . . . . . . . . . . . . . . . . . 4
	2.1. Forcerenew Nonce Authentication . . . . . . . . . . . . . 3		3.1. Forcerenew Nonce Authentication . . . . . . . . . . . . . 4
	2.1.1. Forcerenew Nonce Protocol Capability Option . . . . . 4		3.1.1. Forcerenew Nonce Protocol Capability Option . . . . . 5
	2.1.2. Forcerenew Nonce Protocol . . . . . . . . . . . . . . 6		3.1.2. Forcerenew Nonce Protocol . . . . . . . . . . . . . . 7
	2.1.3. Server considerations for Forcerenew Nonce		3.1.3. Server considerations for Forcerenew Nonce
	Authentication . . . . . . . . . . . . . . . . . . . . 7
	2.1.4. Client considerations for Forcerenew Nonce
	Authentication . . . . . . . . . . . . . . . . . . . . 8		Authentication . . . . . . . . . . . . . . . . . . . . 8
	3. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 9		3.1.4. Client considerations for Forcerenew Nonce
	4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9		Authentication . . . . . . . . . . . . . . . . . . . . 9
	5. Security Considerations . . . . . . . . . . . . . . . . . . . 9		4. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 10
	5.1. Protocol vulnerabilities . . . . . . . . . . . . . . . . . 9		5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
	6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 10		6. Security Considerations . . . . . . . . . . . . . . . . . . . 10
	6.1. Normative References . . . . . . . . . . . . . . . . . . . 10		6.1. Protocol vulnerabilities . . . . . . . . . . . . . . . . . 10
	6.2. Informative References . . . . . . . . . . . . . . . . . . 10		7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 11
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 10		7.1. Normative References . . . . . . . . . . . . . . . . . . . 11
			7.2. Informative References . . . . . . . . . . . . . . . . . . 11
			Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 11
	1. Introduction		1. Introduction
	This document defines extensions to Authentication for DHCP(v4)		The DHCP Reconfigure Extension defined in [RFC3203] is a useful
	Messages [RFC3118] to create a new authentication protocol for DHCPv4		mechanism allowing dynamic reconfiguration of a single host triggered
	Forcerenew [RFC3203] messages. Authentication for DHCP [RFC3118] is		by the DHCP server. Its application is currently limited by a
	mandatory for Forcerenew, however as it is currently defined		requirement that FORCERENEW message is always authenticated using
	[RFC3118] requires distribution of constant token or shared-secret		procedures as described in [RFC3118]. Authentication for DHCP
	out-of-band to DHCP clients. The Forcerenew Nonce is exchanged		[RFC3118] is mandatory for Forcerenew, however as it is currently
	between server and client on initial DHCP ACK and is used for		defined [RFC3118] requires distribution of constant token or shared-
	verification of any subsequent Forcerenew message.		secret out-of-band to DHCP clients. The mandatory authentication was
			originally motivated by a legitimate security concern whereby in some
	Forcerenew Nonce Authentication follows the model set forward in		network environments a FORCERENEW message can be spoofed. However,
	DHCPv6 [RFC3315] as the Reconfigure Key Authentication Protocol.		in some networks native security mechanisms already provide
			sufficient protection against spoofing of DHCP traffic. An example
			of such network is a DSL Forum TR-101 [TR-101] compliant access
			network. In such environments the mandatory coupling between
			FORCERENEW and DHCP Authentication [RFC3118] can be relaxed. This
			document defines extensions to Authentication for DHCP(v4) Messages
			[RFC3118] to create a new authentication protocol for DHCPv4
			Forcerenew [RFC3203] messages; this method does not require out-of-
			band key distribution to DHCP clients. The Forcerenew Nonce is
			exchanged between server and client on initial DHCP ACK and is used
			for verification of any subsequent Forcerenew message.
	1.1. Requirements Language		2. Requirements Language
	The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",		The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
	"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this		"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
	document are to be interpreted as described in RFC 2119 [RFC2119].		document are to be interpreted as described in [RFC2119].
	2. Message authentication		3. Message authentication
	The FORCERENEW message must be authenticated using either [RFC3118]		The FORCERENEW message must be authenticated using either [RFC3118]
	or the proposed Forcerenew Nonce Authentication protocol.		or the proposed Forcerenew Nonce Authentication protocol.
	2.1. Forcerenew Nonce Authentication		3.1. Forcerenew Nonce Authentication
	The Forcerenew nonce authentication protocol provides protection		The Forcerenew nonce authentication protocol provides protection
	against misconfiguration of a client caused by a Forcerenew message		against misconfiguration of a client caused by a Forcerenew message
	sent by a malicious DHCP server. In this protocol, a DHCP server		sent by a malicious DHCP server. In this protocol, a DHCP server
	sends a Forcerenew nonce to the client in the initial exchange of		sends a Forcerenew nonce to the client in the initial exchange of
	DHCP messages. The client records the Forcerenew nonce for use in		DHCP messages. The client records the Forcerenew nonce for use in
	authenticating subsequent Forcerenew messages from that server. The		authenticating subsequent Forcerenew messages from that server. The
	server then includes an HMAC computed from the Forcerenew nonce in		server then includes an HMAC computed from the Forcerenew nonce in
	subsequent Forcerenew messages.		subsequent Forcerenew messages.
	skipping to change at page 4, line 5		skipping to change at page 5, line 16
	HMAC in subsequent Forcerenew messages are carried as the		HMAC in subsequent Forcerenew messages are carried as the
	Authentication information in a DHCP Authentication option. The		Authentication information in a DHCP Authentication option. The
	format of the Authentication information is defined in the following		format of the Authentication information is defined in the following
	section.		section.
	The Forcerenew nonce protocol is used (initiated by the server) only		The Forcerenew nonce protocol is used (initiated by the server) only
	if the client and server are not using any other authentication		if the client and server are not using any other authentication
	protocol and the client and server have negotiated to use the		protocol and the client and server have negotiated to use the
	Forcerenew Nonce Authentication protocol.		Forcerenew Nonce Authentication protocol.
	2.1.1. Forcerenew Nonce Protocol Capability Option		3.1.1. Forcerenew Nonce Protocol Capability Option
	A DHCP client indicates DHCP Forcerenew Nonce Protocol capability by		A DHCP client indicates DHCP Forcerenew Nonce Protocol capability by
	including a FORCERENEW_NONCE_CAPABLE(<TBD>) option in DHCP Discover		including a FORCERENEW_NONCE_CAPABLE(<TBD>) option in DHCP Discover
	and Request messages sent to the server.		and Request messages sent to the server.
	A DHCP server that does not support Forcerenew Nonce Protocol		A DHCP server that does not support Forcerenew Nonce Protocol
	authentication should ignore the FORCERENEW_NONCE_CAPABLE(<TBD>)		authentication should ignore the FORCERENEW_NONCE_CAPABLE(<TBD>)
	option. A DHCP server indicates DHCP Forcerenew Nonce Protocol		option. A DHCP server indicates DHCP Forcerenew Nonce Protocol
	preference by including a FORCERENEW_NONCE_CAPABLE(<TBD>) option in		preference by including a FORCERENEW_NONCE_CAPABLE(<TBD>) option in
	any DHCP Offer messages sent to the client.		any DHCP Offer messages sent to the client.
	A DHCP client MUST NOT send DHCP messages with authentication options		A DHCP client MUST NOT send DHCP messages with authentication options
	where the protocol value is Forcerenew Nonce Authentication(<TBD>).		where the protocol value is Forcerenew Nonce Authentication(<TBD>).
	The FORCERENEW_NONCE_CAPABLE option is a zero length option with code		The FORCERENEW_NONCE_CAPABLE option is a zero length option with code
	of <TDB> and format as follows:		of <TDB> and format as follows:
	Code Len
	+-----+-----+		Code Len
	| TBD | 0 |		+-----+-----+
	+-----+-----+		| TBD | 0 |
			+-----+-----+
	The client would indicate that it supports the functionality by		The client would indicate that it supports the functionality by
	inserting the FORCERENEW_NONCE_CAPABLE option in the DHCP Discover		inserting the FORCERENEW_NONCE_CAPABLE option in the DHCP Discover
	and Request messages. If the server supports Forcerenew nonce		and Request messages. If the server supports Forcerenew nonce
	authentication and is configured to require Forcerenew nonce		authentication and is configured to require Forcerenew nonce
	authentication, it will insert the FORCERENEW_NONCE_CAPABLE option in		authentication, it will insert the FORCERENEW_NONCE_CAPABLE option in
	the DHCP Offer message.		the DHCP Offer message.
	Server Client Server
	(not selected) (selected)
	v v v		Server Client Server
	| | |		(not selected) (selected)
	| Begins initialization |
	| | |
	| _____________/|\____________ |
	|/DHCPDISCOVER | DHCPDISCOVER \|
	| w/Forcerenew- | w/Forcerenew- |
	| Nonce-Capable | Nonce-Capable |
	| | |
	Determines | Determines
	configuration | configuration
	| | |
	|\ | /|
	| \__________ | _________/ |
	| DHCPOFFER \ | /DHCPOFFER |
	|w/Forcerenew \ | /w/Forcerenew|
	|Nonce-Capable \| /Nonce-Capable|
	| | |
	| Collects replies |
	| | |
	| Selects configuration |
	| | |
	| _____________/|\____________ |
	|/ DHCPREQUEST | DHCPREQUEST\ |
	| w/Forcerenew- | w/Forcerenew- |
	| Nonce-Capable | Nonce-Capable |
	| | |
	| | Commits configuration
	| | |
	| |Creates 128-bit Forcerenew Nonce
	| | |
	| | _____________/|
	| |/ DHCPACK |
	| | w/Auth-Proto= |
	| | Forcerenew- |
	| | Nonce |
	| | |
	|Client stores Forcerenew Nonce |
	| | |
	| Initialization complete |
	| | |
	. . .
	. . .
	| | |
	| Forcerenew |
	| | _____________/|
	| |/ DHCPFORCE |
	| | w/Auth-Proto= |
	| | Forcerenew- |
	| | Digest(HMAC)|
	| | |
	| Client checks HMAC digest |
	| using stored Forcerenew Nonce |
	| | |
	| |\____________ |
	| | DHCPREQUEST\ |
	| | w/Forcerenew- |
	| | Nonce-Capable |
	| | |
	| | Commits configuration
	| | |
	| |Creates 128-bit Forcerenew Nonce
	| | |
	| | _____________/|
	| |/ DHCPACK |
	| | w/Auth-Proto= |
	| | Forcerenew- |
	| | Nonce |
	| | |
	| | |
	| | |
	. . .
	. . .
	| | |
	| Graceful shutdown |
	| | |
	| |\ ____________ |
	| | DHCPRELEASE \|
	| | |
	| | Discards lease
	| | |
	v v v
	2.1.2. Forcerenew Nonce Protocol		v v v
			| | |
			| Begins initialization |
			| | |
			| _____________/|\____________ |
			|/DHCPDISCOVER | DHCPDISCOVER \|
			| w/Forcerenew- | w/Forcerenew- |
			| Nonce-Capable | Nonce-Capable |
			| | |
			Determines | Determines
			configuration | configuration
			| | |
			|\ | /|
			| \__________ | _________/ |
			| DHCPOFFER \ | /DHCPOFFER |
			|w/Forcerenew \ | /w/Forcerenew|
			|Nonce-Capable \| /Nonce-Capable|
			| | |
			| Collects replies |
			| | |
			| Selects configuration |
			| | |
			| _____________/|\____________ |
			|/ DHCPREQUEST | DHCPREQUEST\ |
			| w/Forcerenew- | w/Forcerenew- |
			| Nonce-Capable | Nonce-Capable |
			| | |
			| | Commits configuration
			| | |
			| |Creates 128-bit Forcerenew Nonce
			| | |
			| | _____________/|
			| |/ DHCPACK |
			| | w/Auth-Proto= |
			| | Forcerenew- |
			| | Nonce |
			| | |
			|Client stores Forcerenew Nonce |
			| | |
			| Initialization complete |
			| | |
			. . .
			. . .
			| | |
			| Forcerenew |
			| | _____________/|
			| |/ DHCPFORCE |
			| | w/Auth-Proto= |
			| | Forcerenew- |
			| | Digest(HMAC)|
			| | |
			| Client checks HMAC digest |
			| using stored Forcerenew Nonce |
			| | |
			| |\____________ |
			| | DHCPREQUEST\ |
			| | w/Forcerenew- |
			| | Nonce-Capable |
			| | |
			| | Commits configuration
			| | |
			| |Creates 128-bit Forcerenew Nonce
			| | |
			| | _____________/|
			| |/ DHCPACK |
			| | w/Auth-Proto= |
			| | Forcerenew- |
			| | Nonce |
			| | |
			| | |
			| | |
			. . .
			. . .
			| | |
			| Graceful shutdown |
			| | |
			| |\ ____________ |
			| | DHCPRELEASE \|
			| | |
			| | Discards lease
			| | |
			v v v
			3.1.2. Forcerenew Nonce Protocol
	[RFC3118] defined an extensible DHCPv4 authentication option which		[RFC3118] defined an extensible DHCPv4 authentication option which
	supports multiple protocols. The Forcerenew Nonce Protocol makes use		supports multiple protocols. The Forcerenew Nonce Protocol makes use
	of the DHCP authentication option defined in [RFC3118] re-using the		of the DHCP authentication option defined in [RFC3118] re-using the
	option format.		option format.
	The following fields are set in an DHCP authentication option for the		The following fields are set in an DHCP authentication option for the
	Forcerenew Nonce Authentication Protocol:		Forcerenew Nonce Authentication Protocol:
	protocol <TBD (IANA)>		protocol <TBD (IANA)>
			algorithm 1
	algorithm 1
	RDM 0		RDM 0
	The format of the Authentication information for the Forcerenew Nonce		The format of the Authentication information for the Forcerenew Nonce
	Authentication Protocol is:		Authentication Protocol is:
	0 1 2 3		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		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
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Type | Value (128 bits) |		| Type | Value (128 bits) |
	+-+-+-+-+-+-+-+-+ |		+-+-+-+-+-+-+-+-+ |
	. .		. .
	. .		. .
	. +-+-+-+-+-+-+-+-+		. +-+-+-+-+-+-+-+-+
	| |		| |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	Type Type of data in Value field carried in this option:		Type Type of data in Value field carried in this option:
	1 Forcerenew Nonce value (used in ACK message).		1 Forcerenew Nonce value (used in ACK message)
	2 HMAC-MD5 digest of the message (FORCERENEW		2 HMAC-MD5 digest of the message (FORCERENEW message)
	message).
	Value Data as defined by field.		Value Data as defined by field
	2.1.3. Server considerations for Forcerenew Nonce Authentication		3.1.3. Server considerations for Forcerenew Nonce Authentication
	The use of Forcerenew Nonce Protocol is dependent on the client		The use of Forcerenew Nonce Protocol is dependent on the client
	indicating its capability through the FORCERENEW_NONCE_CAPABLE(<TBD>)		indicating its capability through the FORCERENEW_NONCE_CAPABLE(<TBD>)
	DHCP option in any DHCP Discover or Request messages. The DHCP		DHCP option in any DHCP Discover or Request messages. The DHCP
	Discovery or Request message from the client MUST contain the		Discovery or Request message from the client MUST contain the
	FORCERENEW_NONCE_CAPABLE(<TBD>) option if the Forcerenew Nonce		FORCERENEW_NONCE_CAPABLE(<TBD>) option if the Forcerenew Nonce
	Protocol is to be used by the server. The absence of the		Protocol is to be used by the server. The absence of the
	FORCERENEW_NONCE_CAPABLE(<TBD>) option indicates to the server that		FORCERENEW_NONCE_CAPABLE(<TBD>) option indicates to the server that
	the Forcerenew Nonce Authentication protocol is not supported and		the Forcerenew Nonce Authentication protocol is not supported and
	thus the server MUST NOT include a Forcerenew Nonce Protocol		thus the server MUST NOT include a Forcerenew Nonce Protocol
	skipping to change at page 8, line 20		skipping to change at page 9, line 27
	selects a replay detection value according to the RDM selected by the		selects a replay detection value according to the RDM selected by the
	server, and computes an HMAC-MD5 of the Forcerenew message using the		server, and computes an HMAC-MD5 of the Forcerenew message using the
	Forcerenew nonce for the client. The server computes the HMAC-MD5		Forcerenew nonce for the client. The server computes the HMAC-MD5
	over the entire DHCP Forcerenew message, including the Authentication		over the entire DHCP Forcerenew message, including the Authentication
	option; the HMAC-MD5 field in the Authentication option is set to		option; the HMAC-MD5 field in the Authentication option is set to
	zero for the HMAC-MD5 computation. The server includes the HMAC-MD5		zero for the HMAC-MD5 computation. The server includes the HMAC-MD5
	in the authentication information field in an Authentication option		in the authentication information field in an Authentication option
	included in the Forcerenew message sent to the client with type set		included in the Forcerenew message sent to the client with type set
	to 2 (HMAC-MD5 digest).		to 2 (HMAC-MD5 digest).
	2.1.4. Client considerations for Forcerenew Nonce Authentication		3.1.4. Client considerations for Forcerenew Nonce Authentication
	The client MUST indicate Forcerenew nonce Capability by including the		The client MUST indicate Forcerenew nonce Capability by including the
	FORCERENEW_NONCE_CAPABLE(<TBD>) DHCP option (Section 2.1.1) in all		FORCERENEW_NONCE_CAPABLE(<TBD>) DHCP option (Section 2.1.1) in all
	DHCP Discover and Request messages. DHCP servers that support		DHCP Discover and Request messages. DHCP servers that support
	Forcerenew nonce Protocol authentication MUST include the DHCP		Forcerenew nonce Protocol authentication MUST include the DHCP
	Forcerenew Nonce protocol authentication option in DHCP Offers with		Forcerenew Nonce protocol authentication option in DHCP Offers with
	type set to zero(0), allowing the client to use this capability in		type set to zero(0), allowing the client to use this capability in
	selecting DHCP servers should multiple Offers arrive.		selecting DHCP servers should multiple Offers arrive.
	A DHCP server has indicates its support through the inclusion of the		A DHCP server has indicates its support through the inclusion of the
	skipping to change at page 9, line 5		skipping to change at page 10, line 7
	The client will receive a Forcerenew Nonce from the server in the		The client will receive a Forcerenew Nonce from the server in the
	initial DHCP Ack message from the server. The client records the		initial DHCP Ack message from the server. The client records the
	Forcerenew Nonce for use in authenticating subsequent Forcerenew		Forcerenew Nonce for use in authenticating subsequent Forcerenew
	messages.		messages.
	To authenticate a Forcerenew message, the client computes an HMAC-MD5		To authenticate a Forcerenew message, the client computes an HMAC-MD5
	over the DHCP Forcerenew message, using the Forcerenew Nonce received		over the DHCP Forcerenew message, using the Forcerenew Nonce received
	from the server. If this computed HMAC-MD5 matches the value in the		from the server. If this computed HMAC-MD5 matches the value in the
	Authentication option, the client accepts the Forcerenew message.		Authentication option, the client accepts the Forcerenew message.
	3. Contributors		4. Acknowledgements
	Comments are solicited and should be addressed to the DHC WG mailing		Comments are solicited and should be addressed to the DHC WG mailing
	list (dhcwg@ietf.org) and/or the authors. This contribution is based		list (dhcwg@ietf.org) and/or the authors. This contribution is based
	on work by Vitali Vinokour. Major sections of this draft use		on work by Vitali Vinokour. Major sections of this draft use
	modified text from [RFC3315]. The authors wish to thank Ted Lemon		modified text from [RFC3315]. The authors wish to thank Ted Lemon
	and Bernie Volz for their support.		and Bernie Volz for their support.
	4. IANA Considerations		5. IANA Considerations
	This document requests IANA to allocate an option code for the newly		This document requests IANA to allocate an option code for the newly
	defined DHCP option FORCERENEW_NONCE_CAPABALE as described in the		defined DHCP option FORCERENEW_NONCE_CAPABALE as described in the
	text.		text.
	This document requests IANA to allocate a DHCP Authentication		This document requests IANA to allocate a DHCP Authentication
	Option(90) protocol number be assigned for Forcerenew Nonce		Option(90) protocol number be assigned for Forcerenew Nonce
	Authentication, per [RFC3118].		Authentication, per [RFC3118].
	This document requests IANA to create a new namespace associated with		This document requests IANA to create a new namespace associated with
	the Forcerenew Nonce Authentication protocol: algorithm, per		the Forcerenew Nonce Authentication protocol: algorithm, per
	[RFC3118].		[RFC3118].
	5. Security Considerations		6. Security Considerations
	As in some network environments FORCERENEW can be used to snoop and		As in some network environments FORCERENEW can be used to snoop and
	spoof traffic, the FORCERENEW message MUST be authenticated using the		spoof traffic, the FORCERENEW message MUST be authenticated using the
	procedures as described in [RFC3118] or this proposal. In this		procedures as described in [RFC3118] or this proposal. In this
	proposal any party able intercept the nonce exchange could		proposal any party able intercept the nonce exchange could
	impersonate a server and thus offers no protection from man-in-the-		impersonate a server and thus offers no protection from man-in-the-
	middle attacks. FORCERENEW messages failing the authentication		middle attacks. FORCERENEW messages failing the authentication
	should be silently discarded by the client.		should be silently discarded by the client.
	5.1. Protocol vulnerabilities		6.1. Protocol vulnerabilities
	The mechanism described in this document is vulnerable to a denial of		The mechanism described in this document is vulnerable to a denial of
	service attack through flooding a client with bogus FORCERENEW		service attack through flooding a client with bogus FORCERENEW
	messages. The calculations involved in authenticating the bogus		messages. The calculations involved in authenticating the bogus
	FORECERENEW messages may overwhelm the device on which the client is		FORECERENEW messages may overwhelm the device on which the client is
	running.		running.
	The mechanism described provides protection against the use of a		The mechanism described provides protection against the use of a
	FORCERENEW message by a malicious DHCP server to mount a denial of		FORCERENEW message by a malicious DHCP server to mount a denial of
	service or man-in-the-middle attack on a client. This protocol can		service or man-in-the-middle attack on a client. This protocol can
	be compromised by an attacker that can intercept the initial message		be compromised by an attacker that can intercept the initial message
	in which the DHCP server sends the nonce to the client.		in which the DHCP server sends the nonce to the client.
	6. References		7. References
	6.1. Normative References		7.1. Normative References
	[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate		[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
	Requirement Levels", RFC 2119, March 1997.		Requirement Levels", BCP 14, RFC 2119, March 1997.
	[RFC3118] Droms, R. and B. Arbaugh, "Authentication for DHCP		[RFC3118] Droms, R. and W. Arbaugh, "Authentication for DHCP
	Messages", RFC 3118, June 2001.		Messages", RFC 3118, June 2001.
	[RFC3203] T'joens, Y., Hublet, C., and P. De Schrijver, "DHCP		[RFC3203] T'Joens, Y., Hublet, C., and P. De Schrijver, "DHCP
	reconfigure extension", RFC 3203, December 2001.		reconfigure extension", RFC 3203, December 2001.
	6.2. Informative References		7.2. Informative References
	[RFC3315] Droms, R., "Dynamic Host Configuration Protocol for IPv6		[RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C.,
	(DHCPv6)", RFC 3315, July 2003.		and M. Carney, "Dynamic Host Configuration Protocol for
			IPv6 (DHCPv6)", RFC 3315, July 2003.
			[TR-101] Cohen et al, "Architecture & Transport: "Migration to
			Ethernet Based DSL Aggregation, DSL Forum TR-101", 2005.
	Authors' Addresses		Authors' Addresses
	David Miles		David Miles
	Alcatel-Lucent		Alcatel-Lucent
	L3 / 215 Spring St		L3 / 215 Spring St
	Melbourne, Victoria 3000		Melbourne, Victoria 3000,
	Australia		Australia
	Phone: +61 3 9664 3308		Phone: +61 3 9664 3308
			Fax:
	Email: david.miles@alcatel-lucent.com		Email: david.miles@alcatel-lucent.com
			URI:
	Wojciech Dec		Wojciech Dec
	Cisco Systems		Cisco Systems
	Haarlerbergpark Haarlerbergweg 13-19		Haarlerbergpark Haarlerbergweg 13-19
	Amsterdam, NOORD-HOLLAND 1101 CH		Amsterdam, NOORD-HOLLAND 1101 CH
	Netherlands		Netherlands
	Phone:		Phone:
			Fax:
	Email: wdec@cisco.com		Email: wdec@cisco.com
			URI:
	James Bristow		James Bristow
	Swisscom Schweiz AG		Swisscom Schweiz AG
	Zentweg 9		Zentweg 9
	Bern, 3050		Bern, 3050,
	Switzerland		Switzerland
	Phone:		Phone:
			Fax:
	Email: James.Bristow@swisscom.com		Email: James.Bristow@swisscom.com
			URI:
	Roberta Maglione		Roberta Maglione
	Telecom Italia		Telecom Italia
	Via Reiss Romoli 274		Via Reiss Romoli 274
	Torino, 10148		Torino 10148
	Italy		Italy
	Phone:		Phone:
	Email: roberta.maglione@telecomitalia.it		Email: roberta.maglione@telecomitalia.it
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