Network Working Group A. Patel
Internet-Draft K. Leung
Expires: August 11, 2005 Cisco Systems
M. Khalil
H. Akhtar
Nortel Networks
K. Chowdhury
Starent Networks
February 10, 2005
Mobile Node Identifier Option for Mobile IPv6
draft-ietf-mip6-mn-ident-option-02.txt
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Copyright (C) The Internet Society (2005). All Rights Reserved.
Abstract
Mobile IPv6 defines a new Mobility header which is used by mobile
nodes, correspondent nodes, and home agents in all messaging related
to the creation and management of bindings. Mobile IPv6 nodes need
the capability to identify themselves using an identity other than
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the default home IP address. Some examples of identifiers include
NAI, FQDN, IMSI, MSISDN, etc. This document defines a new mobility
option that can be used by Mobile IP6 entities to identify themselves
in messages containing a mobility header.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Mobile Node Identifier option . . . . . . . . . . . . . . . . 5
3.1 MN-NAI mobility option . . . . . . . . . . . . . . . . . . 6
3.2 Processing Considerations . . . . . . . . . . . . . . . . 6
4. Security Considerations . . . . . . . . . . . . . . . . . . . 7
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 9
7. Normative References . . . . . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 9
Intellectual Property and Copyright Statements . . . . . . . . 11
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1. Introduction
The base specification of Mobile IPv6 [RFC3775] identifies mobility
entities using an IPv6 address. It is essential to have a mechanism
wherein mobility entities can be identified using other identifiers
(for example, a network access identifier (NAI) [RFC_2486bis],
International Mobile Station Identifier (IMSI), an application/
deployment specific opaque identifier etc).
The capability to identify a mobility entity via identifiers other
than the IPv6 address can be leveraged for performing various
functions, eg.
o authentication and authorization using an existing AAA
(Authentication, Authorization and Accounting) infrastructure or
via an HLR/AuC (Home Location Register/Authentication Center),
o dynamic allocation of a mobility anchor point,
o dynamic allocation of a home address etc.
This document defines an option with subtype number which denotes a
specific type of identifier. One instance of subtype, the NAI is
defined in Section 3.1. It is anticipated that other identifiers
will be defined for use in the mobility header in the future.
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2. Terminology
The keywords "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.
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3. Mobile Node Identifier option
The Mobile node identifier option is a new optional data field that
is carried in the Mobile IPv6 defined messages which includes the
mobility header. Various forms of identifiers can be used to
identify a MN. Some examples include a Network Access Identifier
(NAI) [RFC_2486bis], an opaque identifier applicable to a particular
application, etc. The subtype field in the option defines the
specific type of identifier.
This option can be used in mobility messages containing a mobility
header. The subtype field in the option is used to interpret the
specific type of identifier.
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 Type | Option Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Subtype | Identifier ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Option Type:
MN-ID-OPTION-TYPE to be defined by IANA. An 8-bit identifier
of the type mobility option.
Option Length:
8-bit unsigned integer, representing the length in octets of
the Subtype and Identifier fields.
Subtype:
Subtype field defines the specific type of identifier included
in the identifier field.
Identifier:
A variable length identifier of type as specified by the
subtype field of this option.
This option does not have any alignment requirements.
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3.1 MN-NAI mobility option
The format of the MN-NAI mobility option is as defined in Section 3.
This option uses the subtype value of 1. The MN-NAI mobility option
is used to identify the mobile node.
The MN-NAI mobility option uses an identifier of the form user@realm
[RFC_2486bis].
3.2 Processing Considerations
The location of the MN identifier option is as follows: When present,
this option MUST appear before any authentication related option in a
message containing a mobility header.
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4. Security Considerations
Mobile IPv6 already contains one mechanism for identifying mobile
nodes, the Home Address Option [RFC 3775]. As a result, the
vulnerabilities of the new option defined in this document are
similar to those that already exist for Mobile IPv6. In particular,
the use of a permanent, stable identifier may compromise the privacy
of the user, making it possible to track a particular device or user
as it moves through different locations.
In addition, since an NAI reveals the home affiliation of a user, it
may assist an attacker in determining the identity of the user, help
the attacker in targeting specific victims, or assist in further
probing of the username space.
These vulnerabilities can be addressed through various mechanisms,
such as those discussed below:
o Encrypting traffic at link layer such that other users on the same
link do not see the identifiers. This mechanism does not help
against attackers on the rest of the path between the mobile node
and its home agent.
o Encrypting the whole packet, such as when using IPsec to protect
the communications with the home agent [RFC 3776].
o Using an authentication mechanism that enables the use of privacy
NAIs [RFC_2486bis] or temporary, changing "pseudonyms" as
identifiers.
In any case, it should be noted that as the identifier option is only
needed on the first registration at the home agent and subsequent
registrations can use the home address, the window of privacy
vulnerability in this document is reduced as compared to the RFC
3775. In addition, this document is a part of a solution to allow
dynamic home addresses to be used. This is an improvement to privacy
as well, and affects both communications with the home agent and the
correspondent nodes, both of which have to be told the home address.
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5. IANA Considerations
IANA services are required for this document. The values for new
mobility options must be assigned from the Mobile IPv6 [RFC3775]
numbering space.
The values for Mobility Option types MN-ID-OPTION-TYPE as defined in
Section 3 need to be assigned. The suggested value is 7 for the
MN-ID-OPTION-TYPE.
IANA should record a value for this new mobility option.
In addition, IANA needs to create a new namespace for the subtype
field of the Mobile Node Identifier Option. The currently allocated
values are as follows:
NAI (defined in this document) [1]
New values for this namespace can be allocated using Standards Action
[RFC2434].
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6. Acknowledgements
The authors would like to thank Basavaraj Patil for his review and
suggestions on this draft. Thanks to Jari Arkko for review and
suggestions regarding security considerations and various other
aspects of the document.
7 Normative References
[RFC2434] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 2434,
October 1998.
[RFC3775] Johnson, D., Perkins, C. and J. Arkko, "Mobility Support
in IPv6", RFC 3775, June 2004.
[RFC_2486bis]
Aboba, et. al., B., "The Network Access Identifier",
draft-ietf-radext-rfc2486bis-03.txt (work in progress),
November 2004.
Authors' Addresses
Alpesh Patel
Cisco Systems
170 W. Tasman Drive
San Jose, CA 95134
US
Phone: +1 408-853-9580
EMail: alpesh@cisco.com
Kent Leung
Cisco Systems
170 W. Tasman Drive
San Jose, CA 95134
US
Phone: +1 408-526-5030
EMail: kleung@cisco.com
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Mohamed Khalil
Nortel Networks
2221 Lakeside Blvd.
Richardson, TX 75082
US
Phone: +1 972-685-0574
EMail: mkhalil@nortelnetworks.com
Haseeb Akhtar
Nortel Networks
2221 Lakeside Blvd.
Richardson, TX 75082
US
Phone: +1 972-684-4732
EMail: haseebak@nortelnetworks.com
Kuntal Chowdhury
Starent Networks
2540 Coolwater Dr.
Plano, TX 75025
US
Phone: +1 214 550 1416
EMail: kchowdury@starentnetworks.com
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