ERP local domain option: The EAP Re-authentication Protocol (ERP) Local Domain Name DHCPv6 Option
A DHCPv6 option that tells a device the local domain name it needs for fast EAP re-authentication.
Zorn, G., Wu, Q., and Y. Wang, "The EAP Re-authentication Protocol (ERP) Local Domain Name DHCPv6 Option", RFC 6440, DOI 10.17487/RFC6440, December 2011, <https://www.rfc-editor.org/info/rfc6440>.
@misc{rfc6440,
series = {Request for Comments},
number = 6440,
howpublished = {RFC 6440},
publisher = {RFC Editor},
doi = {10.17487/RFC6440},
url = {https://www.rfc-editor.org/info/rfc6440},
author = {G. Zorn and Q. Wu and Y. Wang},
title = {{The EAP Re-authentication Protocol (ERP) Local Domain Name DHCPv6 Option}},
pagetotal = 6,
year = 2011,
month = dec,
} RFC text
Contents
Internet Engineering Task Force (IETF) G. Zorn
Request for Comments: 6440 Network Zen
Category: Standards Track Q. Wu
ISSN: 2070-1721 Y. Wang
Huawei
December 2011
The EAP Re-authentication Protocol (ERP) Local Domain Name DHCPv6 Option
Abstract
In order to derive a Domain-Specific Root Key (DSRK) from the
Extended Master Session Key (EMSK) generated as a side effect of an
Extensible Authentication Protocol (EAP) method, the EAP peer must
discover the name of the domain to which it is attached.
This document specifies a Dynamic Host Configuration Protocol
Version 6 (DHCPv6) option designed to allow a DHCPv6 server to inform
clients using the EAP Re-authentication Protocol (ERP) EAP method of
the name of the local domain for ERP.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 5741.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc6440.
Copyright Notice
Copyright (c) 2011 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
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction ....................................................2
2. Terminology .....................................................3
2.1. Standards Language .........................................3
2.2. Acronyms ...................................................3
3. Option Format ...................................................3
3.1. DHCPv6 ERP Local Domain Name Option ........................3
4. Client Behavior .................................................4
5. Relay Agent Behavior ............................................4
6. Security Considerations .........................................4
7. IANA Considerations .............................................4
8. References ......................................................5
8.1. Normative References .......................................5
8.2. Informative References .....................................5
1. Introduction
The EAP Re-authentication Protocol (ERP) [RFC5296] is designed to
allow faster re-authentication of a mobile device that was previously
authenticated by means of the Extensible Authentication Protocol
[RFC3748]. Given that the local root key (e.g., a DSRK, as described
in RFC 5295 [RFC5295]) is generated using the local domain name
(LDN), LDN discovery is an important part of re-authentication. As
described in RFC 5296 [RFC5296], the LDN to be used in ERP can be
learned by the mobile device through the ERP exchange or via a lower-
layer mechanism. However, no lower-layer mechanisms for LDN
discovery have yet been defined.
This document specifies an extension to DHCPv6 for LDN to be used
in ERP.
2. Terminology
2.1. Standards 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].
2.2. Acronyms
o FQDN: Fully Qualified Domain Name
o AAA: Authentication, Authorization, and Accounting
o DSRK: Domain-Specific Root Key
3. Option Format
In DHCPv6-based local domain name discovery, the LDN option is used
by the DHCPv6 client to obtain the local domain name from the DHCPv6
server after full EAP authentication has taken place.
The contents of the ERP Local Domain Name option are intended only
for use with ERP and do not represent the name of a local domain for
any other purposes.
3.1. DHCPv6 ERP Local Domain Name Option
The format of this option is:
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_ERP_LOCAL_DOMAIN_NAME| option-length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| erp-local-domain-name...
+-+-+-+-+-+-+-+-+-+-+-+-+-
option code
OPTION_ERP_LOCAL_DOMAIN_NAME (65)
option-length
Length of the erp-local-domain-name field, in octets
erp-local-domain-name
This field contains the name of the local ERP domain and MUST be
encoded as specified in Section 8 of RFC 3315 [RFC3315]. Note
that this encoding does enable the use of internationalized domain
names, but only as a set of A-labels [RFC5890].
4. Client Behavior
If a DHCPv6 client doesn't know the ERP LDN and requires the DHCPv6
server to provide the DHCPv6 ERP LDN option, it MUST include an
Option Request option requesting the DHCPv6 ERP Local Domain Name
option, as described in Section 22.7 of RFC 3315 [RFC3315].
When the DHCPv6 client receives an ERP Local Domain Name option with
the ERP LDN present in it, it MUST verify that the option length is
no more than 256 octets (the maximum length of a single fully
qualified domain name (FQDN) allowed by the DNS), and that the local
domain name is a properly encoded single FQDN, as specified in
Section 8 of RFC 3315 ("Representation and Use of Domain Names")
[RFC3315].
5. Relay Agent Behavior
If a DHCPv6 relay agent has pre-existing knowledge of the ERP local
domain name for a client (for example, from a previous AAA exchange),
it SHOULD include it in an instance of the DHCPv6 ERP Local Domain
Name option and forward to the DHCPv6 server as a suboption of the
Relay-Supplied Options option [RFC6422].
6. Security Considerations
The communication between the DHCPv6 client and the DHCPv6 server for
the exchange of local domain name information is security sensitive
and requires server authentication and integrity protection. DHCPv6
security as described in [RFC3315] can be used for this purpose.
7. IANA Considerations
IANA has added the name "OPTION_ERP_LOCAL_DOMAIN_NAME" to the
registry titled "Options Permitted in the Relay-Supplied Options
Option" maintained at http://www.iana.org/.
IANA has assigned one new option code to the registry titled "DHCP
Option Codes" maintained at http://www.iana.org/, referencing this
document.
8. References
8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3315] Droms, R., Ed., Bound, J., Volz, B., Lemon, T., Perkins,
C., and M. Carney, "Dynamic Host Configuration Protocol
for IPv6 (DHCPv6)", RFC 3315, July 2003.
[RFC5295] Salowey, J., Dondeti, L., Narayanan, V., and M. Nakhjiri,
"Specification for the Derivation of Root Keys from an
Extended Master Session Key (EMSK)", RFC 5295,
August 2008.
[RFC5296] Narayanan, V. and L. Dondeti, "EAP Extensions for EAP
Re-authentication Protocol (ERP)", RFC 5296, August 2008.
[RFC6422] Lemon, T. and Q. Wu, "Relay-Supplied DHCP Options",
RFC 6422, December 2011.
8.2. Informative References
[RFC3748] Aboba, B., Blunk, L., Vollbrecht, J., Carlson, J., and H.
Levkowetz, Ed., "Extensible Authentication Protocol
(EAP)", RFC 3748, June 2004.
[RFC5890] Klensin, J., "Internationalized Domain Names for
Applications (IDNA): Definitions and Document Framework",
RFC 5890, August 2010.
Authors' Addresses
Glen Zorn
Network Zen
227/358 Thanon Sanphawut
Bang Na, Bangkok 10260
Thailand
Phone: +66 (0) 87-040-4617
EMail: glenzorn@gmail.com
Qin Wu
Huawei Technologies Co., Ltd.
101 Software Avenue, Yuhua District
Nanjing, Jiangsu 210012
China
Phone: +86-25-56623633
EMail: sunseawq@huawei.com
Yungui Wang
Huawei Technologies Co., Ltd.
101 Software Avenue, Yuhua District
Nanjing, Jiangsu 210012
China
Phone: +86-25-56624545
EMail: w52006@huawei.com
AI ELI5
On this page
§1Why ERP Needs a Domain Name
The EAP Re-authentication Protocol (ERP, RFC 5296) allows faster re-authentication of a mobile device that was earlier authenticated with the Extensible Authentication Protocol (RFC 3748). The local root key, for example a Domain-Specific Root Key (DSRK, RFC 5295), is generated using the local domain name (LDN). So the device must discover the LDN.
RFC 5296 says the LDN can be learned through the ERP exchange or by a lower-layer mechanism, but no lower-layer mechanism had yet been defined. RFC 6440 adds an extension to DHCPv6 for this purpose.
To get a quick re-entry pass, your device must know the name of the place it is in. This RFC gives the network a way to tell it.
§2The ERP Local Domain Name Option
The DHCPv6 client uses the option to get the LDN from the DHCPv6 server after full EAP authentication has taken place. The contents are intended only for use with ERP and do not name a local domain for any other purpose.
The option has three parts: the option code OPTION_ERP_LOCAL_DOMAIN_NAME (65), option-length (the length of the name field, in octets), and erp-local-domain-name. The name MUST be encoded as in Section 8 of RFC 3315. That encoding allows internationalized domain names, but only as a set of A-labels (RFC 5890).
The option is a small label with a number, a length, and then the name written in a standard way.
§3Client and Relay Agent Behavior
A DHCPv6 client that does not know the ERP LDN and needs the server to provide it MUST include an Option Request option asking for the ERP Local Domain Name option (Section 22.7 of RFC 3315).
When the client receives the option with an LDN in it, it MUST check that the option length is no more than 256 octets, the maximum length of a single fully qualified domain name (FQDN) allowed by the DNS. It also MUST check that the name is a properly encoded single FQDN.
A DHCPv6 relay agent that already knows the ERP LDN for a client, for example from a previous AAA exchange, SHOULD include it in the option and forward it to the server as a suboption of the Relay-Supplied Options option (RFC 6422).
The device asks 'what is this place called?'. It checks that the answer is a proper name and not too long. A helper in the middle may already know it and pass it along.
§4Security Considerations
The exchange of local domain name information between the DHCPv6 client and server is security sensitive. It requires server authentication and integrity protection. The RFC says the DHCPv6 security described in RFC 3315 can be used for this purpose.
If someone gave your device a fake building name, it could get the wrong badge. So the device should be sure the answer comes from the real network and was not changed on the way.
§5IANA Actions
IANA added the name OPTION_ERP_LOCAL_DOMAIN_NAME to the registry titled "Options Permitted in the Relay-Supplied Options Option". It also assigned one new option code in the "DHCP Option Codes" registry, referencing this document. The option format section gives that code as 65.
The official list of option numbers got a new line, so everyone uses the same number for this option.