Dynamic Host Configuration Working V. Vinokour
Group W. Dec
Internet-Draft Cisco Systems
Intended status: Standards Track J. Bristow
Expires: December 8, 2008 Swisscom Schweiz AG Network
Development
D. Miles
Alcatel-Lucent
June 6, 2008
DHCP Reconfigure Extension Option
draft-vinokour-dhcp-reconfigure-option-00
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Abstract
The current use of DHCP (Dynamic Host Configuration Protocol)
Reconfigure extension is limited by a requirement that FORCERENEW
message is authenticated. This document defines a mechanism allowing
the use of FORCERENEW without DHCP authentication.
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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 RFC 2119 [RFC2119].
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Proposal . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 3
4. Security Considerations . . . . . . . . . . . . . . . . . . . . 4
5. Normative References . . . . . . . . . . . . . . . . . . . . . 4
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 4
Intellectual Property and Copyright Statements . . . . . . . . . . 6
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1. Introduction
The DHCP Reconfigure Extension defined in [RFC3203] is a useful
mechanism allowing dynamic reconfiguration of a single host triggered
by the DHCP server. Its application is currently limited by a
requirement that FORCERENEW message is always authenticated using
procedures as described in [RFC3118]. The mandatory authentication
was originally motivated by a legitimate security concern whereby in
some network environments a FORCERENEW message can be spoofed.
However, in some networks native security mechanisms already provide
sufficient protection against spoofing of DHCP traffic. An example
of such network is a DSL Forum TR-101 [TR-101] compliant access
network.
In such environments the mandatory coupling between FORCERENEW and
DHCP Authentication can be relaxed. This document provides a
mechanism allowing DHCP server and client to negotiate use of
FORCERENEW without authentication.
2. Proposal
We suggest defining a new DHCP option TBD that, when inserted by DHCP
Server in DHCPOFFER and DHCPACK messages, would instruct the client
to enable processing of unauthenticated FORCERENEW messages. The
format of option TBD is as follows:
Code Len Value
+-----+-----+-----+
| TBD | 1 | 0/1 |
+-----+-----+-----+
The client would indicate that it supports the functionality by
inserting an Parameter Request List option (option 55, RFC 3203
[RFC2131]) containing option TBD in DHCPDISCOVER and DHCPREQUEST
messages. In its response the server will only include the option
TBD if it is specified in Parameter Request List received from the
client. The value of the option indicates whether unauthenticated
FORCERENEW messages are permitted in the network (value = 1) or not
(value = 0) thus giving the network administrator control over their
usage. A DHCP client receiving a DHCPOFFER or DHCPACK reply
containing option TBD MUST accept unauthenticated FORCERENEW
messages.
3. IANA Considerations
This document requests IANA to allocate an option code for the newly
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defined DHCP option as described in the text.
Note to RFC Editor: this section may be removed on publication as an
RFC.
4. Security Considerations
The potential security risks of using DHCP reconfigure extension with
unauthenticated FORCERENEW message are outlined in [RFC3203], and led
to the original authentication requirement. Therefore, enabling this
functionality should be done judiciously by network administrators.
5. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2131] Droms, R., "Dynamic Host Configuration Protocol",
RFC 2131, March 1997.
[RFC3118] Droms, R. and W. Arbaugh, "Authentication for DHCP
Messages", RFC 3118, June 2001.
[RFC3203] T'Joens, Y., Hublet, C., and P. De Schrijver, "DHCP
reconfigure extension", RFC 3203, December 2001.
[TR-101] DSLHome-Technical Working Group, "Migration to Ethernet-
Based DSL Aggregation", April 2006,
<http://www.dslforum.org/techwork/tr/TR-101.pdf>.
Authors' Addresses
Vitali Vinokour
Cisco Systems
1414 Massachusetts Ave
Boxborough, MA 01719
USA
Phone: +1-978-936-0774
Fax:
Email: vvinokou@cisco.com
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Wojciech Dec
Cisco Systems
Haarlerbergpark Haarlerbergweg 13-19
Amsterdam, NOORD-HOLLAND 1101 CH
Netherlands
Phone:
Fax:
Email: wdec@cisco.com
URI:
James Bristow
Swisscom Schweiz AG Network Development
Zentweg 9
Bern, 3050
Switzerland
Phone:
Fax:
Email: James.Bristow@swisscom.com
URI:
David Miles
Alcatel-Lucent
Melbourne,
Australia
Phone:
Fax:
Email: david.miles@alcatel-lucent.com
URI:
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