Internet DRAFT - draft-boucadair-dhc-triggered-reconfigure
draft-boucadair-dhc-triggered-reconfigure
DHC Working Group M. Boucadair
Internet-Draft France Telecom
Updates: 3315 (if approved) X. Pougnard
Intended status: Standards Track Orange Labs
Expires: February 28, 2013 August 27, 2012
RECONFIGURE Triggered by DHCPv6 Relay Agents
draft-boucadair-dhc-triggered-reconfigure-01
Abstract
This document defines a new DHCPv6 messages type: RECONFIGURE-
REQUEST. This message is issued by a relay agent to notify a DHCPv6
server a change, which requires issuing a Reconfigure message, has
occurred.
This document updates RFC 3315.
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 February 28, 2013.
Copyright Notice
Copyright (c) 2012 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
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
Boucadair & Pougnard Expires February 28, 2013 [Page 1]
Internet-Draft Relay Triggered Reconfigure August 2012
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Problem . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2. Requirements Language . . . . . . . . . . . . . . . . . . . 4
2. Proposed Solution . . . . . . . . . . . . . . . . . . . . . . . 4
3. RECONFIGURE-REQUEST . . . . . . . . . . . . . . . . . . . . . . 5
3.1. Message Format . . . . . . . . . . . . . . . . . . . . . . 5
3.2. Message Validation . . . . . . . . . . . . . . . . . . . . 5
3.3. Creation and Transmission of RECONFIGURE-REQUEST . . . . . 6
3.4. Server Behaviour . . . . . . . . . . . . . . . . . . . . . 6
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7
5. Security Considerations . . . . . . . . . . . . . . . . . . . . 7
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 7
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 7
7.1. Normative References . . . . . . . . . . . . . . . . . . . 7
7.2. Informative References . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8
Boucadair & Pougnard Expires February 28, 2013 [Page 2]
Internet-Draft Relay Triggered Reconfigure August 2012
1. Introduction
1.1. Problem
[RFC6422] updates DHCPv6 specification [RFC3315] with a new feature
to let a DHCPv6 relay agent communicate information not available at
the DHCPv6 server to a DHCPv6 client. This is achieved owing to the
use of RSOO (Relay-Supplied Options option) which carries
configuration data to the DHCPv6 server. The data conveyed in an
RSOO is then sent back by the DHCPv6 server to the requesting DHCPv6
client.
An illustration example is shown in Figure 1; only a subset of
exchanged messages are represented.
+-------+ +-------+ +-------+
|DHCPv6 | | NAS | |Radius |
|Client | |(DHCPv6| |Server/|
| | | Relay)| | DAC |
+-------+ +-------+ +-------+
| | |
|---Solicit---------------->| |
|---Access-Request---------->|
|<--Access-Accept------------|
| (e.g. DS-Lite-Tunnel-Name)
....
| +-------+
| |DHCPv6 |
| |Server |
| | |
| +-------+
|---Relay-Forward----------->|
| (RSOO(DS-Lite-Tunnel-Name))
|
|<--Relay-Reply--------------|
|<--Advertise---------------|
(e.g., OPTION_AFTR_NAME) |
....
Figure 1: RSOO Flow Example
The change of the configuration may result in RADIUS exchanges
([RFC5176]) between the NAS/DHCPv6 relay agent and Dynamic
Authorization Client (DAC) server as shown in Figure 2. Note the
change of the configuration in the DHCPv6 relay agent can be
triggered by any other out-of-band mechanism.
Boucadair & Pougnard Expires February 28, 2013 [Page 3]
Internet-Draft Relay Triggered Reconfigure August 2012
+-------+ +-------+ +-------+
|DHCPv6 | | NAS | |Radius |
|Client | |(DHCPv6| |Server/|
| | | Relay)| | DAC |
+-------+ +-------+ +-------+
| | |
|<-----CoA-Request-----------|
| (e.g. DS-Lite-Tunnel-Name)
|------CoA-Response--------->|
....
Figure 2: Change of configuration
In the event of the change of the configuration data supplied to the
DHCPv6 server by the DHCPv6 relay agent, DHCPv6 server has no trigger
to issue a Reconfigure message with the updated configuration data.
A solution is sketched in Section 2.
1.2. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
2. Proposed Solution
To solve the problem described in Section 1.1, this document proposes
a new DHCP message called Reconfigure-Request. In the example,
depicted in Figure 3, Reconfigure-Request message is sent by the
DHCPv6 relay agent to a DHCPv6 server when a configuration data
already supplied in an RSOO is detected. Upon receipt of this
message, and if it is configured to support such mode, the DHCPv6
server must build a Reconfigure message. This message is sent to the
DHCPv6 relay and then relayed to the appropriate DHCPv6 client.
This setup assumes the relay has a record of the client, so it has
enough information to send the request to the server. Means to
recover state in failure events must be supported.
Boucadair & Pougnard Expires February 28, 2013 [Page 4]
Internet-Draft Relay Triggered Reconfigure August 2012
+-------+ +-------+ +-------+
|DHCPv6 | | NAS | |Radius |
|Client | |(DHCPv6| |Server/|
| | | Relay)| | DAC |
+-------+ +-------+ +-------+
| | |
|<-----CoA-Request-----------|
| (e.g. DS-Lite-Tunnel-Name)
|------CoA-Response--------->|
....
| +-------+
| |DHCPv6 |
| |Server |
| | |
| +-------+
|---Reconfigure-Request----->|
|
|
|<--Relay-Reply -------------|
|<--Reconfigure-------------| (Reconfigure)
|
....
Figure 3: RECONFIGURE-REQUEST Flow Example
The proposed solution (Reconfigure-Request message) can be used in
other non-RSOO scenarios. It is out of scope of this document to
describe all these scenarios.
3. RECONFIGURE-REQUEST
3.1. Message Format
A new message type code is defined:
RECONFIGURE-REQUEST (To be assigned by IANA, see Section 4).
RECONFIGURE-REQUEST uses the same format as defined in Section 6 of
[RFC3315].
3.2. Message Validation
Clients MUST silently discard any received RECONFIGURE-REQUEST
messages.
Servers MUST silently discard any received RECONFIGURE-REQUEST
messages that meet any of the following conditions:
Boucadair & Pougnard Expires February 28, 2013 [Page 5]
Internet-Draft Relay Triggered Reconfigure August 2012
o the message does not include an OPTION_CLIENTID option.
o the message includes an OPTION_SERVERID option but the contents of
the OPTION_SERVERID option does not match the server's identifier.
Server MUST be configurable to accept or reject RECONFIGURE-REQUEST
messages. If the server is configured to reject RECONFIGURE-REQUEST,
the server MUST silently discard any RECONFIGURE-REQUEST it receives.
Server MUST be configurable to accept or ignore any received
OPTION_RECONF_MSG option in RECONFIGURE-REQUEST messages. If an
OPTION_RECONF_MSG option is received, the server uses the content of
that option as a hint to determine which form of Reconfigure to use.
If the server is configured to ignore any received OPTION_RECONF_MSG
option or if this option is not supplied, the server is supposed to
determine which form of Reconfigure to use.
Because this message provides a mechanism for triggering the DHCP
Reconfigure message, and the DHCP Reconfigure message can be used by
an attacker to control the timing of a DHCP renewal, the DHCP server
MUST have some mechanism for determining that the relay agent is a
trusted entity. RECONFIGURE-REQUEST messages originating from
unknown relay agents MUST be silently dropped.
3.3. Creation and Transmission of RECONFIGURE-REQUEST
In the event of change of an information which has been supplied to
the DHCPv6 server or for other events requiring the server to issue
Reconfigure message, the relay agent determines the client which is
concerned by the change and then builds a Reconfigure-Request
message: the relay agent sets the "msg-type" field to RECONFIFURE-
REQUEST and sets the "transaction-id " field to 0. The relay agent
MAY supply the updated configuration in RSOO as defined in [RFC6422]
and MUST include an OPTION_CLIENTID option [RFC3315] to identify the
client to the DHCPv6 server. The relay agent MAY supply an
OPTION_RECONF_MSG option to indicate which form of Reconfigure to
use.
3.4. Server Behaviour
Upon receipt of a valid Reconfigure-Request message from a DHCPv6
relay agent (see Section 3.2), the server follows the procedure
defined in Section 19.1 of [RFC3315] and, if an RSOO is supplied,
Section 4 of [RFC6422] to construct a Reconfigure message.
As defined in [RFC3315], this message may be sent directly to the
DHCPv6 client or to a relay agent.
Boucadair & Pougnard Expires February 28, 2013 [Page 6]
Internet-Draft Relay Triggered Reconfigure August 2012
4. IANA Considerations
This document requests IANA to assign a new DHCPv6 Message type:
RECONFIGURE-REQUEST
5. Security Considerations
Security considerations elaborated in [RFC3315] and [RFC6422] must be
taken into account. In addition, DHCPv6 servers MAY be configured to
discard relayed RECONFIFURE-REQUEST messages or restrict relay
chaining (see [RFC5007] for more discussion about the rationale of
this recommended behavior). Relay agents SHOULD implement
appropriate means to prevent using RECONFIFURE-REQUEST messages as a
denial-of-service attack on the DHCPv6 servers.
6. Acknowledgements
Many thanks to T. Lemon, R. Maglione, A. Kostur and G. Halwasia for
the comments and review.
7. References
7.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[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.
[RFC6422] Lemon, T. and Q. Wu, "Relay-Supplied DHCP Options",
RFC 6422, December 2011.
7.2. Informative References
[RFC5007] Brzozowski, J., Kinnear, K., Volz, B., and S. Zeng,
"DHCPv6 Leasequery", RFC 5007, September 2007.
[RFC5176] Chiba, M., Dommety, G., Eklund, M., Mitton, D., and B.
Aboba, "Dynamic Authorization Extensions to Remote
Authentication Dial In User Service (RADIUS)", RFC 5176,
January 2008.
Boucadair & Pougnard Expires February 28, 2013 [Page 7]
Internet-Draft Relay Triggered Reconfigure August 2012
Authors' Addresses
Mohamed Boucadair
France Telecom
Rennes, 35000
France
Email: mohamed.boucadair@orange.com
Xavier Pougnard
Orange Labs
Lannion,
France
Phone:
Email: xavier.pougnard@orange.com
Boucadair & Pougnard Expires February 28, 2013 [Page 8]
