draft-ietf-dhc-userclass-08.txt		draft-ietf-dhc-userclass-09.txt
	Internet Engineering Task Force Glenn Stump, IBM
	INTERNET DRAFT Ralph Droms, Bucknell University		Internet Engineering Task Force G. Stump
	Date: June 2000 Ye Gu, Ramesh Vyaghrapuri,		Dynamic Host Configuration Working Group IBM
	Expires: November 2000 Ann Demirtjis, Microsoft		Internet Draft R. Droms
	Burcak Beser, 3Com		Expires: December 2000 Bucknell University
	Jerome Privat, BT		draft-ietf-dhc-userclass-09.txt Y. Gu
			R. Vyaghrapuri
			A. Demirtjis
			Microsoft
			B. Beser
			3Com
			J. Privat
			BT
			July 2000
	The User Class Option for DHCP		The User Class Option for DHCP
	<draft-ietf-dhc-userclass-08.txt>		<draft-ietf-dhc-userclass-09.txt>
	Status of this Memo		Status of this Memo
	The document is an Internet-Draft and is in full conformance with all		This document is an Internet-Draft and is in full conformance with
	of the provisions of Section 10 of RFC 2026.		all provisions of Section 10 of RFC2026.
	Internet-Drafts are working documents of the Internet Engineering		Internet-Drafts are working documents of the Internet Engineering
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	Abstract		Abstract
	This option is used by a DHCP client to optionally identify the		This option is used by a DHCP client to optionally identify the type
	type or category of user or applications it represents. The		or category of user or applications it represents.
	information contained in this option is an opaque field		The information contained in this option is an opaque field that
	that represents the user class of which the client is a member.		represents the user class of which the client is a member.
	Based on this class, a DHCP server selects the appropriate address		Based on this class, a DHCP server selects the appropriate address
	pool to assign an address to the client and the appropriate		pool to assign an address to the client and the appropriate
	configuration parameters.		configuration parameters.
	This option should be configurable by a user.		This option should be configurable by a user.
	1. Introduction		1. Introduction
	It is often desirable to provide different levels of service		It is often desirable to provide different levels of service to
	to different users of an IP network.		different users of an IP network.
	In order for an IP network to implement this service		In order for an IP network to implement this service
	differentiation, it needs a way to classify users. A simple		differentiation, it needs a way to classify users. A simple solution
	solution to this is to use source IP addresses for classification.		to this is to use source IP addresses for classification. Under this
	Under this scheme, network administrators first configure network		scheme, network administrators first configure network devices such
	devices such as routers to recognize traffic from a particular		as routers to recognize traffic from a particular source IP address
	source IP address (or address range) and handle it specially to		(or address range) and handle it specially to meet the desired level
	meet the desired level of service. Next, they assign the IP		of service. Next, they assign the IP addresses to the hosts of the
	addresses to the hosts of the intended users so that the user will		intended users so that the user will receive the appropriate level
	receive the appropriate level of service. They can configure the		of service. They can configure the hosts manually with these
	hosts manually with these addresses. However, they cannot use DHCP		addresses. However, they cannot use DHCP for address assignment,
	for address assignment, even if they are already running a DHCP		even if they are already running a DHCP server in their network. A
	server in their network. A current RFC-compliant DHCP server assigns		current RFC-compliant DHCP server assigns IP addresses based on the
	IP addresses based on the location of the DHCP Client in the network		location of the DHCP Client in the network topology, not the type of
	topology, not the type of user it supports.		user it supports.
	This document describes a simple extension of the DHCP protocol		This document describes a simple extension of the DHCP protocol that
	that enables a DHCP server to assign IP addresses from different		enables a DHCP server to assign IP addresses from different address
	address pools depending on the type of users from which it receives		pools depending on the type of users from which it receives DHCP
	DHCP requests. With this new extension, network administrators will		requests. With this new extension, network administrators will be
	be able to use DHCP to hand out the appropriate addresses to clients.		able to use DHCP to hand out the appropriate addresses to clients.
	An example intended usage is a corporate network subnet consisting		An example intended usage is a corporate network subnet consisting
	of different departments of users, such as Accounting, Legal, Staff,		of different departments of users, such as Accounting, Legal, Staff,
	etc. It may be desirable to allocate logical address pools to each		etc. It may be desirable to allocate logical address pools to each
	of the departments so that network policies may be implemented easily		of the departments so that network policies may be implemented
	on IP address ranges; and this would facilitate providing		easily on IP address ranges; and this would facilitate providing
	differential services, such as network reachibility.		differential services, such as network reachability.
	A DHCP server can also use the information contained in the User		A DHCP server can also use the information contained in the User
	Class to allocate other configuration parameters than the IP		Class to allocate other configuration parameters than the IP
	address. For example, a DHCP server receiving a request from a		address. For example, a DHCP server receiving a request from a
	client with the User Class set to "accounting auditors" may return		client with the User Class set to "accounting auditors" may return
	an option with the address of a particular database server.		an option with the address of a particular database server. Indeed a
	Indeed a DHCP server may have a single pool of addresses and		DHCP server may have a single pool of addresses and only use the
	only use the user class to select parameters other than IP		user class to select parameters other than IP addresses.
	addresses.
	2. Requirements Terminology		2. Requirements Terminology
	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 [3].		document are to be interpreted as described in RFC 2119 [3].
	3. DHCP Terminology		3. DHCP Terminology
	o "DHCP client"		o "DHCP client"
	skipping to change at line 90		skipping to change at line 94
	2. Requirements Terminology		2. Requirements Terminology
	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 [3].		document are to be interpreted as described in RFC 2119 [3].
	3. DHCP Terminology		3. DHCP Terminology
	o "DHCP client"		o "DHCP client"
	A DHCP client or "client" is an Internet host using DHCP to obtain		A DHCP client or "client" is an Internet host using DHCP to obtain
	configuration parameters such as a network address.		configuration parameters such as a network address.
	o "DHCP server"		o "DHCP server"
			A DHCP server or "server" is an Internet host that returns
	A DHCP server of "server"is an Internet host that returns
	configuration parameters to DHCP clients.		configuration parameters to DHCP clients.
	o "binding"		o "binding"
			A binding is a collection of configuration parameters, including at
	A binding is a collection of configuration parameters, including		least an IP address, associated with or "bound to" a DHCP client.
	at least an IP address, associated with or "bound to" a DHCP		Bindings are managed by DHCP servers.
	client. Bindings are managed by DHCP servers.
	4. User Class option		4. User Class option
	This option is used by a DHCP client to optionally identify the		This option is used by a DHCP client to optionally identify the type
	type or category of user or applications it represents.		or category of user or applications it represents.
	A DHCP server uses the User Class option to choose the address		A DHCP server uses the User Class option to choose the address pool
	pool it allocates an address from and/or to select any other		it allocates an address from and/or to select any other
	configuration option.		configuration option.
	This option is a DHCP option [1, 2].		This option is a DHCP option [1, 2].
	This option MAY carry multiple User Classes.		This option MAY carry multiple User Classes.
	Servers may interpret the meanings of multiple class		Servers may interpret the meanings of multiple class specifications
	specifications in an implementation dependent or		in an implementation dependent or configuration dependent manner,
	configuration dependent manner, and so the use of multiple		and so the use of multiple classes by a DHCP client should be based
	classes by a DHCP client should be based on the specific server		on the specific server implementation and configuration which will
	implementation and configuration which will be used to process		be used to process that User class option.
	that User class option.
	The format of this option is as follows:		The format of this option is as follows:
	Code Len Value		Code Len Value
	+-----+-----+--------------------- . . . --+		+-----+-----+--------------------- . . . --+
	| 77 | N | User Class Data ('Len' octets) |		| 77 | N | User Class Data ('Len' octets) |
	+-----+-----+--------------------- . . . --+		+-----+-----+--------------------- . . . --+
	where Value consists of zero or more instances of User Class Data.		where Value consists of one or more instances of User Class Data.
	Each instance of User Class Data is formatted as follows:		Each instance of User Class Data is formatted as follows:
	UC_Len_i User_Class_Data_i		UC_Len_i User_Class_Data_i
	+--------+------------------------ . . . --+		+--------+------------------------ . . . --+
	| L_i | Opaque-Data ('UC_Len_i' octets) |		| L_i | Opaque-Data ('UC_Len_i' octets) |
	+--------+------------------------ . . . --+		+--------+------------------------ . . . --+
	Each User Class value (User_Class_Data_i) is indicated as an opaque		Each User Class value (User_Class_Data_i) is indicated as an opaque
	field.		field.
	The value in UC_Len_i does not include the length field itself		The value in UC_Len_i does not include the length field itself and
	and MUST be non-zero.		MUST be non-zero.
	Let m be the number of User Classes carried in the option. The		Let m be the number of User Classes carried in the option. The
	length of the option as specified in Len must be the sum of the		length of the option as specified in Len must be the sum of the
	lengths of each of the class names plus m:		lengths of each of the class names plus m:
	Len= UC_Len_1 + UC_Len_2 + ... + UC_Len_m + m.		Len= UC_Len_1 + UC_Len_2 + ... + UC_Len_m + m.
	If any instances of User Class Data are present, the minimum		If any instances of User Class Data are present, the minimum value
	value of Len is two (Len = UC_Len_1 + 1 = 1 + 1 = 2).		of Len is two (Len = UC_Len_1 + 1 = 1 + 1 = 2).
	The Code for this option is 77.		The Code for this option is 77.
	A server that is not equipped to interpret any given user class		A server that is not equipped to interpret any given user class
	specified by a client MUST ignore it (although it may be reported).		specified by a client MUST ignore it (although it may be reported).
	If a server recognizes one or more user classes specified by the		If a server recognizes one or more user classes specified by the
	client, but does not recognize one or more other user classes		client, but does not recognize one or more other user classes
	specified by the client, the server MAY use the user classes it		specified by the client, the server MAY use the user classes it
	recognizes.		recognizes.
	DHCP clients implementing this option SHOULD allow users to enter		DHCP clients implementing this option SHOULD allow users to enter
	one or more user class values.		one or more user class values.
	5. IANA Considerations		5. IANA Considerations
	Option 77, which IANA has already assigned for this purpose,		Option 77, which IANA has already assigned for this purpose, should
	should be used as the User Class Option for DHCP.		be used as the User Class Option for DHCP.
	6. Security Considerations		6. Security Considerations
	DHCP currently provides no authentication or security		DHCP currently provides no authentication or security mechanisms.
	mechanisms. Potential exposures to attack are discussed		Potential exposures to attack are discussed is section 7 of the
	is section 7 of the protocol specification [1].		protocol specification [1].
	This lack of authentication mechanism means that a DHCP server		This lack of authentication mechanism means that a DHCP server
	cannot check if a client or user is authorised to use a		cannot check if a client or user is authorised to use a given User
	given User Class.		Class.
	This introduces an obvious vulnerability when using the User		This introduces an obvious vulnerability when using the User Class
	Class option. For example, if the User Class is used to give		option. For example, if the User Class is used to give out special
	out special IP addresses that have better QoS associated with		IP addresses that have better QoS associated with them (as described
	them (as described in section 1), there is no way to authenticate		in section 1), there is no way to authenticate a client and it is
	a client and it is therefore impossible to check if a client is		therefore impossible to check if a client is authorised to use such
	authorised to use such an IP address.		an IP address.
	7. References		7. References
	[1] Droms, R., "Dynamic Host Configuration Protocol", RFC 2131,		[1] Droms, R., "Dynamic Host Configuration Protocol", RFC 2131,
	March 1997.		March 1997.
	[2] S. Alexander, R. Droms, "DHCP Options and BOOTP Vendor		[2] Alexander, S., and Droms R., "DHCP Options and BOOTP Vendor
	Extensions", RFC 2132, March 1997.		Extensions", RFC 2132, March 1997.
	[3] Bradner, S., "Key words for use in RFCs to Indicate Requirement		[3] Bradner, S., "Key words for use in RFCs to Indicate Requirement
	Levels," RFC 2119, March 1997.		Levels," RFC 2119, March 1997.
	8. Acknowledgments		8. Acknowledgments
			This document is based on earlier drafts by Glenn Stump, Ralph
	This document is based on earlier drafts by Glenn Stump,		Droms, Ye Gu, Ramesh Vyaghrapuri and Burcak Beser.
	Ralph Droms, Ye Gu, Ramesh Vyaghrapuri and Burcak Beser.		Thanks to Ted Lemon, Steve Gonczi, Kim Kinnear, Bernie Volz, Richard
	Thanks to Ted Lemon, Steve Gonczi, Kim Kinnear, Bernie Volz,		Jones, Barr Hibbs and Thomas Narten for their comments and
	Richard Jones, Barr Hibbs and Thomas Narten for their comments		suggestions.
	and suggestions.
	9. Author Information		9. Author Information
	Glenn Stump		Glenn Stump
	IBM Networking Software		IBM Networking Software
	P.O. Box 12195		P.O. Box 12195
	RTP, NC 27709		RTP, NC 27709
	Phone: (919) 301-4277		Phone: (919) 301-4277
	Email: stumpga@us.ibm.com		Email: stumpga@us.ibm.com
	skipping to change at line 244		skipping to change at line 243
	Rolling Meadows, IL		Rolling Meadows, IL
	Phone: 847 262 2195		Phone: 847 262 2195
	Email: Burcak_Beser@3com.com		Email: Burcak_Beser@3com.com
	Ann Demirtjis		Ann Demirtjis
	Microsoft Corporation		Microsoft Corporation
	One Microsoft Way		One Microsoft Way
	Redmond WA 98052		Redmond WA 98052
	Phone: 425-705-2254		Phone: 425-705-2254
	Email: annd@microsoft.com		Email: annd@microsoft.com
	Jerome Privat		Jerome Privat
	BT Advanced Communications Technology Centre		BT Advanced Communications Technology Centre
	Adastral Park, Martlesham Heath, IP5 3RE		Adastral Park, Martlesham Heath, IP5 3RE
	UK		UK
	Phone: +44 1473 648910		Phone: +44 1473 606304
	Email: jerome.privat@bt.com		Email: jerome.privat@bt.com
	10. Expiration		Full Copyright Statement
	This document will expire on November 2000.
	Copyright Statement		"Copyright (C) The Internet Society (2000). All Rights Reserved.
	Copyright (c) The Internet Society (1999). All Rights Reserved.
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