Internet DRAFT - draft-yeh-dhc-dhcpv6-authorization-opt
draft-yeh-dhc-dhcpv6-authorization-opt
DHC Working Group L. Yeh, Ed.
Internet-Draft Huawei Technologies
Intended status: Standards Track M. Boucadair
Expires: October 27, 2012 France Telecom
T. Lemon
Nominum, Inc
April 25, 2012
RADIUS Option for DHCPv6 Relay Agents on Broadband Access Server
draft-yeh-dhc-dhcpv6-authorization-opt-01
Abstract
The DHCPv6 RADIUS option provides a communication mechanism between
relay agent and the server. This mechanism can help the centralized
DHCPv6 server to select the right configuration for the client based
on the authorization information received from a separate RADIUS
server which is not located at the same place of DHCPv6 server in the
cases where the NAS acts as DHCPv6 relay agent and RADIUS client
simultaneously.
Status of this Memo
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology and Language . . . . . . . . . . . . . . . . . . . 3
3. Network Scenarios . . . . . . . . . . . . . . . . . . . . . . . 4
4. OPTION_RADIUS . . . . . . . . . . . . . . . . . . . . . . . . . 6
5. Relay Agent Behavior . . . . . . . . . . . . . . . . . . . . . 6
6. Server Behavior . . . . . . . . . . . . . . . . . . . . . . . . 7
7. Client Behavior . . . . . . . . . . . . . . . . . . . . . . . . 7
8. Security Considerations . . . . . . . . . . . . . . . . . . . . 7
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 7
11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 7
11.1. Normative References . . . . . . . . . . . . . . . . . . . 7
11.2. Informative References . . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8
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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], and etc. The stateless
configuration parameters [RFC3736] include, for example, DNS
[RFC3646]. The DHCPv6 server is typically deployed in the central
part of an ISP network.
RADIUS [RFC2865], an essentially stateless protocol, is used widely
as the centralized authentication, authorization and user management
mechanism for the service provision in Broadband access network.
[RFC3162], [RFC4818] and [ietf-radext-ipv6-access-06] specify
attributes that supports the provision of service for IPv6 access.
RADIUS authorizes that the NAS assigns an IPv6 address or prefix from
the indicated pool, or assigns an IPv6 address or prefix with an
explicitly indicated value in the attributes for the subscribers.
These mechanisms work well in the deployment scenario where the NAS
acts as the distributed DHCPv6 server. In this case the NAS responds
as the indication conveyed by the attributes in the Access-Accept
message from the RADIUS server. These mechanisms also work 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 DHCPv6 option for the distributed Relay
Agent to transfer the authorization information of RADIUS attributes
received in the Access-Accept message to the centralized DHCPv6
server. This document should be read in conjunction with the
following specifications: [RFC2865], [RFC2869], [RFC3315] and
[RFC4818]. These specifications will help the reader to understand
how DHCPv6 and RADIUS work together to provide IPv6 service.
Definitions for terms and acronyms not specified in this document are
defined in [RFC2865], [RFC2869], [RFC3315] and [RFC4818].
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 shows 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 relay agent and the RADIUS client
simultaneously. Figure 1 shows the sequence of DHCPv6 and RADIUS
messages for IPoE access mode. Figure 2 shows the sequence of DHCPv6
and RADIUS messages for PPPoE access mode.
+-------+ +-------+ +-------+
|DHCPv6 | Access Mode: | NAS | |Radius |
|Client | IPoE |(DHCPv6| |Server |
| | | Relay)| | |
+-------+ +-------+ +-------+
| | |
|---Solicit---------------->| |
|---Access-Request---------->|
|<--Access-Accept------------|
| (e.g. Framed-Pool)
| (e.g. Delegated-IPv6-Prefix)
DHCPv6 messages RADIUS messages
| +-------+
| |DHCPv6 |
| |Server |
| | |
| +-------+
|---Relay-Forward----------->|
| (OPTION_RADIUS)
|
|<--Relay-Reply -------------|
|<--Advertise---------------|
(e.g. Prefix, Address) |
|---Request---------------->|
(e.g. Prefix, Address) |
|---Relay-Forward----------->|
| (OPTION_RADIUS)
|
|<--Relay-Reply -------------|
|<--Reply-------------------|
(e.g. Prefix, Address) |
DHCPv6 messages DHCPv6 messages
Figure 1: Network scenario and message sequence when employing DHCPv6
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RADIUS option in IPoE access
+-------+ +-------+ +-------+
|DHCPv6 | Access Mode: | NAS | |Radius |
|Client | PPPoE |(DHCPv6| |Server |
| | | Relay)| | |
+-------+ +-------+ +-------+
| | |
|--PPP LCP Config-Request-->| |
|---Access-Request---------->|
|<--Access-Accept------------|
| (e.g. Framed-Pool)
| (e.g. Delegated-IPv6-Prefix)
|
|<----PPP LCP Config-ACK----|
PPP messages RADIUS messages
| +-------+
| |DHCPv6 |
| |Server |
| | |
| +-------+
|---Solicit---------------->| |
|---Relay-Forward----------->|
| (OPTION_RADIUS)
|
|<--Relay-Reply -------------|
|<--Advertise---------------|
(e.g. Prefix, Address) |
|---Request---------------->|
(e.g. Prefix, Address) |
|---Relay-Forward----------->|
| (OPTION_RADIUS)
|
|<--Relay-Reply -------------|
|<--Reply-------------------|
(e.g. Prefix, Address) |
DHCPv6 messages DHCPv6 messages
Figure 2: Network scenario and message sequence when employing DHCPv6
RADIUS option in PPPoE access
If the authorization through RADIUS fails, the associated message
sequences will stop. The DHCPv6 relay will not forward the message
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from the client to the server.
4. OPTION_RADIUS
The OPTION_RADIUS is a stateless DHCPv6 option, and is used by the
relay agent to carry the authorization information of RADIUS
attributes received in the Access-Accept message.
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-length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RADIUS Attributes...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
option-code TBD
option-length Length of the option-data in Octets
option-data One or a list of RADIUS Attributes
The option-data of OPTION_RADIUS is one or a list of RADIUS
attributes received in the Access-Accept message from the RADIUS
server. As the same method in [RFC4014], only the attributes listed
in the table below may be included in the OPTION_RADIUS.
Type Code Attribute Reference
26 Vendor-Specific [RFC2865]
88 Framed-Pool [RFC2869]
123 Delegated-IPv6-Prefix [RFC4818]
[TBD] Framed-IPv6-Address [ietf-radext-ipv6-access-06]
Note: The above table might have more attributes in the future.
5. Relay Agent Behavior
The DHCPv6 relay agent may include OPTION_RADIUS in the RELAY-FORW
message. When the value in the attributes of Framed-Pool (88), (or
Stateful-IPv6-Address-Pool, Delegated-IPv6-Prefix-Pool,) Delegated-
IPv6-Prefix (123) and 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 in the
container option, OPTION_RADIUS. The relay agent MUST ignore
OPTION_RADIUS if received.
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6. Server Behavior
Upon receipt of the RELAY-FORW 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
SHOULD ignore this option. The DHCPv6 server MUST NOT include
OPTION_RADIUS in RELAY-REPL messages.
7. Client Behavior
OPTION_RADIUS option 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.
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].
9. IANA Considerations
The authors of this document request to assign a new DHCPv6 option
code for OPTION_RADIUS.
10. Acknowledgements
Expert comments from Bernie Volz and Tomek Mrugalski for the
discussion on the technology selection in the mailing list are
appreciated.
11. References
11.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
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[RFC2865] Rigney, C., Willens, S., Rubens, A., and W. Simpson,
"Remote Authentication Dial In User Service (RADIUS)",
RFC 2865, June 2000.
[RFC2869] Rigney, C., Willats, W., and P. Calhoun, "RADIUS
Extensions", RFC 2869, 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.
[RFC3736] Droms, R., "Stateless Dynamic Host Configuration Protocol
(DHCP) Service for IPv6", RFC 3736, April 2004.
[RFC4014] Droms, R. and J. Schnizlein, "Remote Authentication
Dial-In User Service (RADIUS) Attributes Suboption for the
Dynamic Host Configuration Protocol (DHCP) Relay Agent
Information Option", RFC 4014, February 2005.
[RFC4818] Salowey, J. and R. Droms, "RADIUS Delegated-IPv6-Prefix
Attribute", RFC 4818, April 2007.
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.
[ietf-radext-ipv6-access-06]
Lourdelet, B., Dec, W., Sarikaya, B., Zorn, G., and D.
Miles, "RADIUS attributes for IPv6 Access Networks",
July 2011.
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Authors' Addresses
Leaf Y. Yeh (editor)
Huawei Technologies
P. R. China
Email: leaf.y.yeh@huawei.com
Mohamed Boucadair
France Telecom
France
Email: mohamed.boucadair@orange.com
Ted Lemon
Nominum, Inc
USA
Email: Ted.Lemon@nominum.com
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