draft-ietf-dhc-agentopt-radius-01.txt   draft-ietf-dhc-agentopt-radius-02.txt 
Network Working Group R. Droms Network Working Group R. Droms
Internet-Draft J. Schnizlein Internet-Draft J. Schnizlein
Expires: April 23, 2003 Cisco Systems Expires: April 30, 2003 Cisco Systems
October 23, 2002 October 30, 2002
RADIUS Attributes Sub-option for the DHCP Relay Agent Information RADIUS Attributes Sub-option for the DHCP Relay Agent Information
Option Option
draft-ietf-dhc-agentopt-radius-01.txt draft-ietf-dhc-agentopt-radius-02.txt
Status of this Memo Status of this Memo
This document is an Internet-Draft and is in full conformance with This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026. 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
Task Force (IETF), its areas, and its working groups. Note that Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet- other groups may also distribute working documents as Internet-
Drafts. Drafts.
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and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt. http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html. http://www.ietf.org/shadow.html.
This Internet-Draft will expire on April 23, 2003. This Internet-Draft will expire on April 30, 2003.
Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2002). All Rights Reserved. Copyright (C) The Internet Society (2002). All Rights Reserved.
Abstract Abstract
A network access device may choose to authenticate the identity of a A network access device may choose to authenticate the identity of a
device before granting that device access to the network. The IEEE device before granting that device access to the network. The IEEE
802.1X protocol is an example of a mechanism for providing 802.1X protocol is an example of a mechanism for providing
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address for assignment to the device through its DHCP client. The address for assignment to the device through its DHCP client. The
RADIUS Attributes sub-option enables a network element to pass along RADIUS Attributes sub-option enables a network element to pass along
attributes for the user of a device received during RADIUS attributes for the user of a device received during RADIUS
authentication to a DHCP server. authentication to a DHCP server.
1. Introduction and Background 1. Introduction and Background
The RADIUS Attributes sub-option for the DHCP Relay Agent option The RADIUS Attributes sub-option for the DHCP Relay Agent option
provides a way through which network elements can pass information provides a way through which network elements can pass information
obtained through layer 2 authentication to a DHCP server [4]. IEEE obtained through layer 2 authentication to a DHCP server [4]. IEEE
802.1X [2] is an example of a mechanism through which a device such 802.1X [2] is an example of a mechanism through which a network
as a switch or a wireless LAN access point can authenticate the access device such as a switch or a wireless LAN access point can
identity of the user of a device before providing layer 2 network authenticate the identity of the user of a device before providing
access. In 802.1X authenticated access, a device must first exchange layer 2 network access using RADIUS [3] as the Authentication Service
some authentication credentials with the network access device. The specified in 802.1X. In 802.1X authenticated access, a device must
access device then supplies these credentials to a RADIUS server [3], first exchange some authentication credentials with the network
which either confirms or denies the identity of the user of the access device. The access device then supplies these credentials to
device requesting network access. The access device, based on the a RADIUS server, which either confirms or denies the identity of the
reply of the RADIUS server, then allows or denies network access to user of the device requesting network access. The access device,
the requesting device. based on the reply of the RADIUS server, then allows or denies
network access to the requesting device.
Figure 1 summarizes the message exchange among the participants in Figure 1 summarizes the message exchange among the participants in
IEEE 802.1X authentication. IEEE 802.1X authentication.
+-----------------+ +-----------------+
|Device requesting| |Device requesting|
| network access | | network access |
+-----------------+ +-----------------+
| ^ | ^
| | | |
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The following terms are used as defined in RFC2131 and RFC3046: DHCP The following terms are used as defined in RFC2131 and RFC3046: DHCP
relay agent, DHCP server, DHCP client. relay agent, DHCP server, DHCP client.
2.3 RADIUS Terminology 2.3 RADIUS Terminology
The following terms are used in conjunction with RADIUS: The following terms are used in conjunction with RADIUS:
RADIUS server: An entity that provides RADIUS server: An entity that provides
RADIUS service through the exchange of RADIUS protocol messages RADIUS service through the exchange of RADIUS protocol messages
Attribute or attribute-value pair (AVP): Data value carried in a Attribute: Data value carried in a RADIUS protocol message
RADIUS protocol message
2.4 802.1X Terminology 2.4 802.1X Terminology
The following terms are used as defined in the IEEE 802.1X protocol: The following terms are used as defined in the IEEE 802.1X protocol:
Authenticator, Supplicant. Authenticator, Supplicant.
3. RADIUS Attributes sub-option format 3. RADIUS Attributes sub-option format
The RADIUS Attributes Sub-option is a new sub-option for the DHCP The RADIUS Attributes Sub-option is a new sub-option for the DHCP
Relay Agent option. Relay Agent option.
The format of the RADIUS Attributes sub-option is: The format of the RADIUS Attributes sub-option is:
SubOpt Len RADIUS attributes SubOpt Len RADIUS attributes
code code
+-------+-----+------+------+------+------+--...-+------+ +-------+-----+------+------+------+------+--...-+------+
| TBD | N | b1 | b2 | b3 | b4 | | bN | | TBD | N | b1 | b2 | b3 | b4 | | bN |
+-------+-----+------+------+------+------+--...-+------+ +-------+-----+------+------+------+------+--...-+------+
The RADIUS attributes are carried as attribute-value pairs (AVPs), The RADIUS attributes are encoded according to the encoding rules in
encoded according to the encoding rules in RFC 2865, in bytes RFC 2865, in bytes b1...bN.
b1...bN.
4. DHCP Relay Agent Behavior 4. DHCP Relay Agent Behavior
When the DHCP relay agent receives a DHCP message from the client, it When the DHCP relay agent receives a DHCP message from the client, it
MAY append a DHCP Relay Agent Information option containing the MAY append a DHCP Relay Agent Information option containing the
RADIUS Attributes sub-option, along with any other sub-options it is RADIUS Attributes sub-option, along with any other sub-options it is
configured to supply. The RADIUS Attributes sub-option MUST contain configured to supply. The RADIUS Attributes sub-option MUST contain
the attributes received in response to the client's authentication the attributes received in response to the client's authentication
with the RADIUS service. The DHCP relay agent MUST NOT add more than with the RADIUS service. The DHCP relay agent MUST NOT add more than
one RADIUS Attributes sub-option in a message. one RADIUS Attributes sub-option in a message.
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10. Terms of Use 10. Terms of Use
Cisco has a pending patent which relates to the subject matter of Cisco has a pending patent which relates to the subject matter of
this Internet Draft. If a standard relating to this subject matter this Internet Draft. If a standard relating to this subject matter
is adopted by IETF and any claims of any issued Cisco patents are is adopted by IETF and any claims of any issued Cisco patents are
necessary for practicing this standard, any party will be able to necessary for practicing this standard, any party will be able to
obtain a license from Cisco to use any such patent claims under obtain a license from Cisco to use any such patent claims under
openly specified, reasonable, non-discriminatory terms to implement openly specified, reasonable, non-discriminatory terms to implement
and fully comply with the standard. and fully comply with the standard.
References Normative References
[1] Bradner, S., "Key words for use in RFCs to Indicate Requirement [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997. Levels", BCP 14, RFC 2119, March 1997.
[2] Institute of Electrical and Electronics Engineers, "Port based [2] Institute of Electrical and Electronics Engineers, "Port based
Network Access Control", IEEE Standard 802.1X, March 2001. Network Access Control", IEEE Standard 802.1X, March 2001.
[3] Rigney, C., Willens, S., Rubens, A. and W. Simpson, "Remote [3] Rigney, C., Willens, S., Rubens, A. and W. Simpson, "Remote
Authentication Dial In User Service (RADIUS)", RFC 2865, June Authentication Dial In User Service (RADIUS)", RFC 2865, June
2000. 2000.
[4] Droms, R., "Dynamic Host Configuration Protocol", RFC 2131, [4] Droms, R., "Dynamic Host Configuration Protocol", RFC 2131,
March 1997. March 1997.
[5] Patrick, M., "DHCP Relay Agent Information Option", RFC 3046, [5] Patrick, M., "DHCP Relay Agent Information Option", RFC 3046,
January 2001. January 2001.
Informative References
[6] Droms, R. and W. Arbaugh, "Authentication for DHCP Messages", [6] Droms, R. and W. Arbaugh, "Authentication for DHCP Messages",
RFC 3118, June 2001. RFC 3118, June 2001.
[7] Lemon, T. and M. Stapp, "The Authentication Suboption for the [7] Lemon, T. and M. Stapp, "The Authentication Suboption for the
DHCP Relay Agent Option", draft-ietf-dhc-auth-suboption-00 (work DHCP Relay Agent Option", draft-ietf-dhc-auth-suboption-00 (work
in progress), June 2002. in progress), June 2002.
Authors' Addresses Authors' Addresses
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