RADIUS Option for DHCPv6 Relay Agent on the Broadband Access Servers
draft-ietf-dhc-dhcpv6-radius-opt-09
The information below is for an old version of the document.
| Document | Type |
This is an older version of an Internet-Draft that was ultimately published as RFC 7037.
|
|
|---|---|---|---|
| Authors | Leaf Yeh , Mohamed Boucadair | ||
| Last updated | 2013-03-19 (Latest revision 2013-02-25) | ||
| RFC stream | Internet Engineering Task Force (IETF) | ||
| Formats | |||
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by Martin Thomson
Ready w/issues
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| Additional resources | Mailing list discussion | ||
| Stream | WG state | WG Consensus: Waiting for Write-Up | |
| Document shepherd | Tomek Mrugalski | ||
| IESG | IESG state | I-D Exists | |
| Consensus boilerplate | Unknown | ||
| Telechat date | (None) | ||
| Responsible AD | (None) | ||
| Send notices to | (None) |
draft-ietf-dhc-dhcpv6-radius-opt-09
DHC Working Group L. Yeh
Internet-Draft Freelancer Technologies
Intended status: Standards Track M. Boucadair
Expires: August 29, 2013 France Telecom
February 25, 2013
RADIUS Option for DHCPv6 Relay Agent on the Broadband Access Servers
draft-ietf-dhc-dhcpv6-radius-opt-09
Abstract
The DHCPv6 RADIUS option provides a mechanism to exchange
authorization and identification information between the DHCPv6 relay
agent and the DHCPv6 server. This mechanism is meant for the
centralized DHCPv6 server to select the right configuration for the
requesting DHCPv6 client based on the authorization information
received from the RADIUS server, which is not co-located with the
DHCPv6 server. The Network Access Server (NAS) acts as DHCPv6 relay
agent and RADIUS client simultaneously in this document.
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
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."
This Internet-Draft will expire on August 29, 2013.
Copyright Notice
Copyright (c) 2013 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
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
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to this document. Code Components extracted from this document must
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.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology and Language . . . . . . . . . . . . . . . . . . . 3
3. Network Scenarios . . . . . . . . . . . . . . . . . . . . . . 4
4. DHCPv6 RADIUS option . . . . . . . . . . . . . . . . . . . . . 7
5. Relay Agent Behavior . . . . . . . . . . . . . . . . . . . . . 8
6. Server Behavior . . . . . . . . . . . . . . . . . . . . . . . 8
7. Client Behavior . . . . . . . . . . . . . . . . . . . . . . . 8
8. Security Considerations . . . . . . . . . . . . . . . . . . . 9
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 9
11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 9
11.1. Normative References . . . . . . . . . . . . . . . . . . 9
11.2. Informative References . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 10
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1. Introduction
DHCPv6 provides a mechanism that allows the server to assign or
delegate both stateful and stateless configuration parameters to the
clients. The stateful configuration parameters include IPv6 address
[RFC3315], IPv6 prefix [RFC3633], etc. The stateless configuration
parameters [RFC3736] include, for example, DNS [RFC3646], or a FQDN
of AFTR [RFC6334]. In the scenarios described in this document, the
DHCPv6 server is deployed in the central part of an ISP network.
RADIUS [RFC2865] is widely used as the centralized authentication,
authorization and user management mechanism for the service provision
in Broadband access network. [RFC3162], [RFC4818], [RFC6519] and
[I-D.ietf-radext-ipv6-access] specified attributes that support the
service provision for IPv6-only and IPv6-transition access. RADIUS
server authorizes the Network Access Server (NAS) to assign an IPv6
address or prefix from the indicated pool, or to assign an IPv6
address or prefix with an explicitly indicated value, and other
configuration parameters as per the attributes for the subscribers.
These mechanisms work well in the deployment scenarios where the NAS
acts as the distributed DHCPv6 server. In that case the NAS directly
responds the DHCPv6 messages as per the indication conveyed by the
attributes in the Access-Accept message from the RADIUS server.
These mechanisms might also work well in the scenario where the
centralized DHCPv6 server is co-located with the RADIUS server, where
they can share the same database of the users. But when the NAS acts
as the relay agent and RADIUS client simultaneously, and the
centralized DHCPv6 server is not located in the same place as the
RADIUS server, a new communication mechanism is needed for the relay
agent to transfer the authorization information indicated by the
RADIUS attributes to the DHCPv6 server.
2. Terminology and Language
This document specifies a new DHCPv6 option for the DHCPv6 Relay
Agent to transfer the authorization information of RADIUS attributes
received in the Access-Accept message from the RADIUS server to the
centralized DHCPv6 server. Definitions for terms and acronyms not
specified in this document are defined in [RFC2865] and [RFC3315].
The keywords MUST, MUST NOT, REQUIRED, SHALL, SHALL NOT, SHOULD,
SHOULD NOT, RECOMMENDED, MAY, and OPTIONAL, when they appear in this
document, are to be interpreted as described in BCP 14, [RFC2119].
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3. Network Scenarios
Figure 1 and Figure 2 show the typical network scenarios where the
communication mechanism introduced in this document is necessary. In
these scenarios, the centralized DHCPv6 server is not co-located with
the RADIUS server, but both of them are in the same administrative
domain. The NAS acts as the DHCPv6 relay agent and the RADIUS client
simultaneously. Figure 1 shows the sequence of DHCPv6 and RADIUS
messages for IP over Ethernet (IPoE) access model, when the access
loop adopts the direct Ethernet encapsulation. Figure 2 shows the
sequence of DHCPv6 and RADIUS messages for PPP over Ethernet (PPPoE)
access model.
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+-------+ +-------+ +-------+
|DHCPv6 | Access Model: | NAS | |Radius |
|Client | IPoE | | |Server |
+-------+ +-------+ +-------+
| | |
|---Solicit---------------->| |
| |---Access-Request---------->|
| | |
| |<--Access-Accept------------|
| |(e.g. Delegated-IPv6-Prefix)|
| | |
DHCPv6 messages RADIUS messages
+-------+
|DHCPv6 |
|Server |
+-------+
| | |
| |---Relay-forward----------->|
| | (OPTION_RADIUS) |
| | |
| |<--Relay-reply -------------|
|<--Advertise---------------| |
| (e.g. IA_PD) | |
| | |
|---Request---------------->| |
| (e.g. IA_PD) |---Relay-forward----------->|
| | (OPTION_RADIUS) |
| | |
| |<--Relay-reply -------------|
|<--Reply-------------------| |
| (e.g. IA_PD) | |
| | |
DHCPv6 messages DHCPv6 messages
Figure 1: Network scenario and message sequence when employing DHCPv6
RADIUS option in IPoE access
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+-------+ +-------+ +-------+
|DHCPv6 | Access Model: | NAS | |Radius |
|Client | PPPoE | | |Server |
+-------+ +-------+ +-------+
| | |
|--PPP LCP Config-Request-->| |
| |---Access-Request---------->|
| | |
| |<--Access-Accept------------|
|<----PPP LCP Config-ACK----|(e.g. Delegated-IPv6-Prefix)|
| | |
PPP messages RADIUS messages
+-------+
|DHCPv6 |
|Server |
+-------+
| | |
|---Solicit---------------->| |
| |---Relay-forward----------->|
| | (OPTION_RADIUS) |
| | |
| |<--Relay-reply -------------|
|<--Advertise---------------| |
| (e.g. IA_PD) | |
| | |
|---Request---------------->| |
| (e.g. IA_PD) |---Relay-forward----------->|
| | (OPTION_RADIUS)
| | |
| |<--Relay-reply -------------|
|<--Reply-------------------| |
| (e.g. IA_PD) | |
| | |
DHCPv6 messages DHCPv6 messages
Figure 2: Network scenario and message sequence when employing DHCPv6
RADIUS option in PPPoE access
If the authentication or the authorization through RADIUS fails, the
associated message sequences will stop. The NAS acting as the DHCPv6
relay agent will not forward the message received from the client to
the DHCPv6 server. If the authentication or the authorization
through RADIUS passes, the NAS MUST store the information indicated
in the RADIUS attributes received in the Access-Accept message from
the RADIUS server during the whole session. How the NAS manages
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these information during the RADIUS session is out of the scope of
this document.
After receiving RENEW (5) message from the DHCPv6 client, the NAS
SHOULD NOT initiate a new Access-Request/Access-Accept message
exchange with the RADIUS server; but after receiving REBIND (6)
message from the DHCPv6 client, the NAS SHOULD initiate a new Access-
Request/Access-Accept message exchange with the RADIUS server.
4. DHCPv6 RADIUS option
The OPTION_RADIUS is a DHCPv6 option used by the DHCPv6 relay agent
to carry the authorization information of RADIUS attributes received
in the Access-Accept message from the RADIUS server.
The format of the OPTION_RADIUS option is defined as follows:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_RADIUS | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| option-data (List of RADIUS Attributes)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
option-code TBD
option-len Length of the option-data in octets
option-data List of one or more RADIUS attributes
The option-data of OPTION_RADIUS is a list of one or more RADIUS
attributes received in the Access-Accept message from the RADIUS
server. Only the attributes listed in the IANA Registry of 'RADIUS
Attributes Permitted in the DHCPv6 RADIUS option' SHOULD be included
in the OPTION_RADIUS.
The RADIUS attributes listed in the below table are recommended as
the first batch of attributes in the IANA Registry of 'RADIUS
Attributes Permitted in the DHCPv6 RADIUS option'. New RADIUS
attributes MAY be added to this list after the IETF Expert Review
[RFC5226].
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Type Code Attribute Reference
26 Vendor-Specific [RFC2865]
123 Delegated-IPv6-Prefix [RFC4818]
144 DS-Lite-Tunnel-Name [RFC6519]
[TBD] Framed-IPv6-Address [I-D.ietf-radext-ipv6-access]
[TBD] Stateful-IPv6-Address-Pool [I-D.ietf-radext-ipv6-access]
[TBD] Delegated-IPv6-Prefix-Pool [I-D.ietf-radext-ipv6-access]
[TBD] DNS-Server-IPv6-Address [I-D.ietf-radext-ipv6-access]
Note: The definition of the RADIUS attribute's 'Length' field in
section 5 of [RFC2865] includes the length of 'Type' and 'Length'
fields.
According to the network scenarios described in section 3, the
OPTION_RADIUS SHOULD appear in the RELAY-FORW (12) message relaying
SOLICIT (1), REQUEST (3) and REBIND (6) from the DHCPv6 client, and
MAY appear in the RELAY-FORW (12) relaying any other message from the
DHCPv6 client.
5. Relay Agent Behavior
The DHCPv6 relay agent MAY include OPTION_RADIUS in the RELAY-FORW
(12) message. When the value in the attributes of Stateful-IPv6-
Address-Pool, Delegated-IPv6-Prefix-Pool, Delegated-IPv6-Prefix (123)
or Framed-IPv6-Address in the Access-Accept message replied from
RADIUS server are valid, the relay agent that supports OPTION_RADIUS
SHOULD include these RADIUS attributes into the container option,
OPTION_RADIUS.
6. Server Behavior
Upon receipt of the RELAY-FORW (12) message with OPTION_RADIUS from a
relay agent, the DHCPv6 server SHOULD extract and interpret the
RADIUS attributes in the OPTION_RADIUS, and use that information in
selecting configuration parameters for the requesting client. If the
DHCPv6 server does not support OPTION_RADIUS, the DHCPv6 server MUST
silently discard this option.
7. Client Behavior
OPTION_RADIUS is only exchanged between the relay agents and the
servers. DHCPv6 clients are not aware of the usage of OPTION_RADIUS.
DHCPv6 client MUST NOT send OPTION_RADIUS, and MUST ignore
OPTION_RADIUS if received.
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8. Security Considerations
Known security vulnerabilities of the DHCPv6 and RADIUS protocol MAY
apply to its options. Security issues related with DHCPv6 are
described in section 23 of [RFC3315]. Security issues related with
RADIUS are described in section 8 of [RFC2865], section 5 of
[RFC3162].
The mechanism described in this document may introduce new attack
vector against the DHCPv6 server in case the DHCPv6 relay agent is
compromised. By forging the RADIUS attributes contained in the
OPTION_RADIUS of the RELAY-FORW (12) messages, the attacker may
influence the parameter assignment on the DHCPv6 server for the
DHCPv6 clients. However, in the network scenarios described in the
section 3, NAS could always be regarded as a trusted network
component in the real deployment.
9. IANA Considerations
This document requests to assign a new DHCPv6 option code for
OPTION_RADIUS, and to create a new registry on the same assignment
page, which can be entitled as 'RADIUS Attributes Permitted in the
DHCPv6 RADIUS option'. The new registry will enumerate the RADIUS
Attributes Types
(http://www.iana.org/assignments/radius-types/radius-types.xml) that
are permitted to be included in the DHCPv6 RADIUS option. New RADIUS
attributes MAY be added to this list after the IETF Expert Review
[RFC5226]. The IETF expert review SHOULD include careful
consideration of the security implications of allowing the relay
agent to include the RADIUS attribute being considered for addition
to this registry.
10. Acknowledgements
Thanks to Tomek Mrugalski, Bernie Volz, Gaurav Halwasia and Roberta
Maglione for their thorough review comments in the mailing list of
DHC working group, to Ted Lemon for his continuous encouragement and
technical guidance.
11. References
11.1. Normative References
[I-D.ietf-radext-ipv6-access]
Dec, W., Sarikaya, B., Zorn, G., Miles, D., and B.
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Lourdelet, "RADIUS attributes for IPv6 Access Networks",
draft-ietf-radext-ipv6-access-15 (work in progress),
January 2013.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2865] Rigney, C., Willens, S., Rubens, A., and W. Simpson,
"Remote Authentication Dial In User Service (RADIUS)",
RFC 2865, June 2000.
[RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C.,
and M. Carney, "Dynamic Host Configuration Protocol for
IPv6 (DHCPv6)", RFC 3315, July 2003.
[RFC4818] Salowey, J. and R. Droms, "RADIUS Delegated-IPv6-Prefix
Attribute", RFC 4818, April 2007.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
May 2008.
[RFC6519] Maglione, R. and A. Durand, "RADIUS Extensions for Dual-
Stack Lite", RFC 6519, February 2012.
11.2. Informative References
[RFC3162] Aboba, B., Zorn, G., and D. Mitton, "RADIUS and IPv6",
RFC 3162, August 2001.
[RFC3633] Troan, O. and R. Droms, "IPv6 Prefix Options for Dynamic
Host Configuration Protocol (DHCP) version 6", RFC 3633,
December 2003.
[RFC3646] Droms, R., "DNS Configuration options for Dynamic Host
Configuration Protocol for IPv6 (DHCPv6)", RFC 3646,
December 2003.
[RFC3736] Droms, R., "Stateless Dynamic Host Configuration Protocol
(DHCP) Service for IPv6", RFC 3736, April 2004.
[RFC6334] Hankins, D. and T. Mrugalski, "Dynamic Host Configuration
Protocol for IPv6 (DHCPv6) Option for Dual-Stack Lite",
RFC 6334, August 2011.
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Authors' Addresses
Leaf Y. Yeh
Freelancer Technologies
P. R. China
Email: leaf.yeh.sdo@gmail.com
Mohamed Boucadair
France Telecom
France
Email: mohamed.boucadair@orange.com
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