draft-ietf-radext-chargeable-user-id-05.txt   draft-ietf-radext-chargeable-user-id-06.txt 
Network Working Group F. Adrangi Network Working Group F. Adrangi
Internet-Draft Intel Internet-Draft Intel
Expires: October 3, 2005 A. Lior Expires: April 15, 2006 A. Lior
Bridgewater Systems Bridgewater Systems
J. Korhonen J. Korhonen
Teliasonera Teliasonera
J. Loughney J. Loughney
Nokia Nokia
April 2005 October 12, 2005
Chargeable User Identity Chargeable User Identity
draft-ietf-radext-chargeable-user-id-05 draft-ietf-radext-chargeable-user-id-06
Status of this Memo Status of this Memo
This document is an Internet-Draft and is subject to all provisions By submitting this Internet-Draft, each author represents that any
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which he or she become aware will be disclosed, in accordance with
RFC 3668.
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Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2005). Copyright (C) The Internet Society (2005).
Abstract Abstract
This document describes a new RADIUS attribute, Chargeable-User- This document describes a new RADIUS attribute, Chargeable-User-
Identity. This attribute can be used by a home network to identify a Identity. This attribute can be used by a home network to identify a
user for the purpose of roaming transactions that occur outside of user for the purpose of roaming transactions that occur outside of
the home network. the home network.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1 Motivation . . . . . . . . . . . . . . . . . . . . . . . . 4 1.1. Motivation . . . . . . . . . . . . . . . . . . . . . . . . 4
1.2 Terminology . . . . . . . . . . . . . . . . . . . . . . . 5 1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 5
2. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . 5 2. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1 Chargeable-User-Identity (CUI) Attribute . . . . . . . . . 5 2.1. Chargeable-User-Identity (CUI) Attribute . . . . . . . . . 5
2.2 CUI Attribute . . . . . . . . . . . . . . . . . . . . . . 7 2.2. CUI Attribute . . . . . . . . . . . . . . . . . . . . . . 7
3. Attribute Table . . . . . . . . . . . . . . . . . . . . . . . 7 3. Attribute Table . . . . . . . . . . . . . . . . . . . . . . . 7
4. Diameter Consideration . . . . . . . . . . . . . . . . . . . . 7 4. Diameter Consideration . . . . . . . . . . . . . . . . . . . . 8
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
6. Security considerations . . . . . . . . . . . . . . . . . . . 8 6. Security considerations . . . . . . . . . . . . . . . . . . . 8
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 8 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 8
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 8 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 9
8.1 Normative references . . . . . . . . . . . . . . . . . . . 8 8.1. Normative references . . . . . . . . . . . . . . . . . . . 9
8.2 Informative references . . . . . . . . . . . . . . . . . . 9 8.2. Informative references . . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 9 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 10
Intellectual Property and Copyright Statements . . . . . . . . 11 Intellectual Property and Copyright Statements . . . . . . . . . . 11
1. Introduction 1. Introduction
Some authentication methods, including EAP-PEAP, EAP-TTLS, EAP-SIM Some authentication methods, including EAP-PEAP, EAP-TTLS, EAP-SIM
and EAP-AKA, can hide the true identity of the user from RADIUS and EAP-AKA, can hide the true identity of the user from RADIUS
servers outside of the user's home network. In these methods, the servers outside of the user's home network. In these methods, the
User-Name(1) attribute contains an anonymous identity (e.g., User-Name(1) attribute contains an anonymous identity (e.g.,
@example.com) sufficient to route the RADIUS packets to the home @example.com) sufficient to route the RADIUS packets to the home
network but otherwise insufficient to identify the user. While this network but otherwise insufficient to identify the user. While this
mechanism is good practice in some circumstances, there are problems mechanism is good practice in some circumstances, there are problems
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using RADIUS. Missing elements include mechanisms for billing and using RADIUS. Missing elements include mechanisms for billing and
fraud prevention. fraud prevention.
The CUI attribute is intended to close operational loopholes in The CUI attribute is intended to close operational loopholes in
RADIUS specifications that have impacted roaming solutions RADIUS specifications that have impacted roaming solutions
negatively. Use of the CUI is geared toward EAP methods supporting negatively. Use of the CUI is geared toward EAP methods supporting
privacy (such as PEAP and EAP-TTLS), which are, for the most part, privacy (such as PEAP and EAP-TTLS), which are, for the most part,
recent deployments. A chargeable identity reflecting the user recent deployments. A chargeable identity reflecting the user
profile by the home network is needed in such roaming scenarios. profile by the home network is needed in such roaming scenarios.
1.1 Motivation 1.1. Motivation
Some other mechanisms have been proposed in place of the CUI Some other mechanisms have been proposed in place of the CUI
attribute. These mechanisms are insufficient or cause other attribute. These mechanisms are insufficient or cause other
problems. It has been suggested that standard RADIUS Class(25) or problems. It has been suggested that standard RADIUS Class(25) or
User-Name(1) attributes could be used to indicate the CUI. However, User-Name(1) attributes could be used to indicate the CUI. However,
in a complex global roaming environment where there could be one or in a complex global roaming environment where there could be one or
more intermediaries between the NAS and the home RADIUS server, the more intermediaries between the NAS and the home RADIUS server, the
use of aforementioned attributes could lead to problems as described use of aforementioned attributes could lead to problems as described
below. below.
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within an Access-Accept packet to the RADIUS client, so that the within an Access-Accept packet to the RADIUS client, so that the
CUI can be included in the accounting packets. CUI can be included in the accounting packets.
The CUI attribute provides a solution to the above problems and The CUI attribute provides a solution to the above problems and
avoids overloading RADIUS User-Name(1) attribute or changing the avoids overloading RADIUS User-Name(1) attribute or changing the
usage of existing RADIUS Class(25) attribute. The CUI therefore usage of existing RADIUS Class(25) attribute. The CUI therefore
provides a standard approach to billing and fraud prevention when EAP provides a standard approach to billing and fraud prevention when EAP
methods supporting privacy are used. It does not solve all related methods supporting privacy are used. It does not solve all related
problems, but does provide for billing and fraud prevention. problems, but does provide for billing and fraud prevention.
1.2 Terminology 1.2. 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 [RFC2119]. document are to be interpreted as described in [RFC2119].
3GPP - Third Generation Partnership Program 3GPP - Third Generation Partnership Program
AAA - Authentication, Authorization and Accounting AAA - Authentication, Authorization and Accounting
CUI - Chargeable-User-Identity CUI - Chargeable-User-Identity
GSMA - GSM Association GSMA - GSM Association
IRAP - International Roaming Access Protocols Program IRAP - International Roaming Access Protocols Program
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TTLS - Tunneled Transport Layer Security TTLS - Tunneled Transport Layer Security
WISPr - Wireless ISP Roaming WISPr - Wireless ISP Roaming
WPA - Wi-Fi Protected Access WPA - Wi-Fi Protected Access
2. Operation 2. Operation
This document assumes that the RADIUS protocol operates as specified This document assumes that the RADIUS protocol operates as specified
in [RFC2865], [RFC2866], dynamic authorization as specified in in [RFC2865], [RFC2866], dynamic authorization as specified in
[RFC3576], and the Diameter protocol as specified in [RFC3588]. [RFC3576], and the Diameter protocol as specified in [RFC3588].
2.1 Chargeable-User-Identity (CUI) Attribute 2.1. Chargeable-User-Identity (CUI) Attribute
The CUI attribute serves as an alias to the user's real identity, The CUI attribute serves as an alias to the user's real identity,
representing a chargeable identity as defined and provided by the representing a chargeable identity as defined and provided by the
home network as a supplemental or alternative information to User- home network as a supplemental or alternative information to User-
Name(1). Typically the CUI represents the identity of the actual Name(1). Typically the CUI represents the identity of the actual
user but it may also indicate other chargeable identities such as a user but it may also indicate other chargeable identities such as a
group of users. RADIUS clients (proxy or NAS) outside the home group of users. RADIUS clients (proxy or NAS) outside the home
network MUST NOT modify the CUI attribute. network MUST NOT modify the CUI attribute.
The RADIUS server (a RADIUS proxy, home RADIUS server) may include The RADIUS server (a RADIUS proxy, home RADIUS server) may include
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in response to an Access-Request packet from a given NAS, even if the in response to an Access-Request packet from a given NAS, even if the
NAS has indicated that it supports CUI. NAS has indicated that it supports CUI.
If an Access-Accept packet without the CUI attribute was received by If an Access-Accept packet without the CUI attribute was received by
a RADIUS client that requested the CUI attribute, then the Access- a RADIUS client that requested the CUI attribute, then the Access-
Accept packet MAY be treated as an Access-Reject. Accept packet MAY be treated as an Access-Reject.
If the CUI was included in an Access-Accept packet, RADIUS clients If the CUI was included in an Access-Accept packet, RADIUS clients
supporting the CUI attribute MUST ensure that the CUI attribute supporting the CUI attribute MUST ensure that the CUI attribute
appears in the RADIUS Accounting-Request (Start, Interim, and Stop). appears in the RADIUS Accounting-Request (Start, Interim, and Stop).
This requirement applies regardless of whether the RADIUS client
requested the CUI attribute.
RFC 2865 includes the following statements about behaviors of RADIUS RFC 2865 includes the following statements about behaviors of RADIUS
client and server with respect to unsupported attributes: client and server with respect to unsupported attributes:
- "A RADIUS client MAY ignore Attributes with an unknown Type." - "A RADIUS client MAY ignore Attributes with an unknown Type."
- "A RADIUS server MAY ignore Attributes with an unknown Type." - "A RADIUS server MAY ignore Attributes with an unknown Type."
Therefore, RADIUS clients or servers that do not support the CUI may Therefore, RADIUS clients or servers that do not support the CUI may
ignore the attribute. ignore the attribute.
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Otherwise, if the Access-Request packet does not contain a CUI, the Otherwise, if the Access-Request packet does not contain a CUI, the
home RADIUS server SHOULD NOT include the CUI attribute in the home RADIUS server SHOULD NOT include the CUI attribute in the
Access-Accept packet. The Access-Request may be sent either in the Access-Accept packet. The Access-Request may be sent either in the
initial authentication or during re-authentication. initial authentication or during re-authentication.
A NAS that requested the CUI during re-authentication by including A NAS that requested the CUI during re-authentication by including
the CUI in the Access-Request, will receive the CUI in the Access- the CUI in the Access-Request, will receive the CUI in the Access-
Accept. The NAS MUST include the value of that CUI in all Accounting Accept. The NAS MUST include the value of that CUI in all Accounting
Messages. Messages.
2.2 CUI Attribute 2.2. CUI Attribute
A summary of the RADIUS CUI Attribute is given below. A summary of the RADIUS CUI Attribute is given below.
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 | Length | String... | Type | Length | String...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type: TBD for Chargeable-User-Identity. Type: TBD for Chargeable-User-Identity.
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CUI TBA CUI TBA
6. Security considerations 6. Security considerations
It is strongly recommended that the CUI format used is such that the It is strongly recommended that the CUI format used is such that the
real user identity is not revealed. Furthermore, where a reference real user identity is not revealed. Furthermore, where a reference
is used to a real user identity, the binding lifetime of that is used to a real user identity, the binding lifetime of that
reference to the real user be kept as short as possible. reference to the real user be kept as short as possible.
The RADIUS entities (RADIUS proxies and clients) outside the home The RADIUS entities (RADIUS proxies and clients) outside the home
netowrk MUST NOT modify the CUI. However, there is no way to detect network MUST NOT modify the CUI or insert a CUI in an Access-Accept.
or prevent this. However, there is no way to detect or prevent this.
Attempting theft of service, A man-in-the-middle may try to insert,
modify or remove the CUI in the Access-Accept packets and Accounting
packets. However, RADIUS Access-Accept and Accounting packets
already provide integrity protection.
If the NAS includes CUI in an Access-Request packet, a man-in-the- If the NAS includes CUI in an Access-Request packet, a man-in-the-
middle may remove it. This will cause the Access-Accept packet to middle may remove it. This will cause the Access-Accept packet to
not include a CUI attribute, which may cause the NAS to reject the not include a CUI attribute, which may cause the NAS to reject the
session. To prevent such a DoS attack, the NAS SHOULD include a session. To prevent such a DoS attack, the NAS SHOULD include a
Message-Authenticator(80) attribute within Access-Request packets Message-Authenticator(80) attribute within Access-Request packets
containing a CUI attribute. containing a CUI attribute.
7. Acknowledgements 7. Acknowledgements
The authors would like to thank Jari Arkko, Bernard Aboba, David The authors would like to thank Jari Arkko, Bernard Aboba, David
Nelson, Barney Wolff, Blair Bullock, Sami Ala-Luukko, Lothar Reith, Nelson, Barney Wolff, Blair Bullock, Sami Ala-Luukko, Lothar Reith,
David Mariblanca, Eugene Chang, Greg Weber, and Mark Grayson, for David Mariblanca, Eugene Chang, Greg Weber, and Mark Grayson, for
their feedback and guidance. their feedback and guidance.
8. References 8. References
8.1 Normative references 8.1. Normative references
[RFC2865] Rigney, C., Willens, S., Rubens, A., and W. Simpson, [RFC2865] Rigney, C., Willens, S., Rubens, A., and W. Simpson,
"Remote Authentication Dial In User Service (RADIUS)", "Remote Authentication Dial In User Service (RADIUS)",
RFC 2865, June 2000. RFC 2865, June 2000.
[RFC2866] Rigney, C., "RADIUS Accounting", RFC 2866, June 2000. [RFC2866] Rigney, C., "RADIUS Accounting", RFC 2866, June 2000.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[rfc2486bis] [rfc2486bis]
Aboba, B., Beadles, M., Arkko, J., and P. Eronen, "The Aboba, B., Beadles, M., Arkko, J., and P. Eronen, "The
Network Access Identifier", Network Access Identifier",
draft-arkko-roamops-rfc2486bis-02 (work in progress), draft-arkko-roamops-rfc2486bis-02 (work in progress),
July 2004. July 2004.
8.2 Informative references 8.2. Informative references
[RFC3576] Chiba, M., Dommety, G., Eklund, M., Mitton, D., and B. [RFC3576] Chiba, M., Dommety, G., Eklund, M., Mitton, D., and B.
Aboba, "Dynamic Authorization Extensions to Remote Aboba, "Dynamic Authorization Extensions to Remote
Authentication Dial In User Service (RADIUS)", RFC 3576, Authentication Dial In User Service (RADIUS)", RFC 3576,
July 2003. July 2003.
[RFC3588] Calhoun, P., Loughney, J., Guttman, E., Zorn, G., and J. [RFC3588] Calhoun, P., Loughney, J., Guttman, E., Zorn, G., and J.
Arkko, "Diameter Base Protocol", RFC 3588, September 2003. Arkko, "Diameter Base Protocol", RFC 3588, September 2003.
Authors' Addresses Authors' Addresses
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