draft-ietf-mip4-rfc3012bis-02.txt   draft-ietf-mip4-rfc3012bis-03.txt 
Network Working Group Charles E. Perkins Network Working Group Charles E. Perkins
Internet-Draft Nokia Research Center Internet-Draft Nokia Research Center
Expires: December 10, 2004 Pat R. Calhoun Expires: June 2, 2005 Pat R. Calhoun
Black Storm Networks Black Storm Networks
Jayshree. Bharatia Jayshree. Bharatia
Nortel Networks Nortel Networks
June 11, 2004 December 2, 2004
Mobile IPv4 Challenge/Response Extensions (revised) Mobile IPv4 Challenge/Response Extensions (revised)
draft-ietf-mip4-rfc3012bis-02.txt draft-ietf-mip4-rfc3012bis-03.txt
Status of this Memo Status of this Memo
By submitting this Internet-Draft, I certify that any applicable This document is an Internet-Draft and is subject to all provisions
patent or other IPR claims of which I am aware have been disclosed, of section 3 of RFC 3667. By submitting this Internet-Draft, each
and any of which I become aware will be disclosed, in accordance with author represents that any applicable patent or other IPR claims of
which he or she is aware have been or will be disclosed, and any of
which he or she become aware will be disclosed, in accordance with
RFC 3668. RFC 3668.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as other groups may also distribute working documents as
Internet-Drafts. Internet-Drafts.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt. http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html. http://www.ietf.org/shadow.html.
This Internet-Draft will expire on December 10, 2004. This Internet-Draft will expire on June 2, 2005.
Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2004). All Rights Reserved. Copyright (C) The Internet Society (2004).
Abstract Abstract
Mobile IP, as originally specified, defines an authentication Mobile IP, as originally specified, defines an authentication
extension (the Mobile-Foreign Authentication extension) by which a extension (the Mobile-Foreign Authentication extension) by which a
mobile node can authenticate itself to a foreign agent. mobile node can authenticate itself to a foreign agent.
Unfortunately, that extension does not provide the foreign agent any Unfortunately, that extension does not provide the foreign agent any
direct guarantee that the protocol is protected from replays, and direct guarantee that the protocol is protected from replays, and
does not allow for the use of existing techniques (such as CHAP) for does not allow for the use of existing techniques (such as CHAP) for
authenticating portable computer devices. authenticating portable computer devices.
skipping to change at page 4, line 18 skipping to change at page 4, line 18
allow a mobile node to authenticate itself to a foreign agent. Such allow a mobile node to authenticate itself to a foreign agent. Such
authentication mechanisms are mostly external to the principal authentication mechanisms are mostly external to the principal
operation of Mobile IP, since the foreign agent can easily route operation of Mobile IP, since the foreign agent can easily route
packets to and from a mobile node whether or not the mobile node is packets to and from a mobile node whether or not the mobile node is
reporting a legitimately owned home address to the foreign agent. reporting a legitimately owned home address to the foreign agent.
Unfortunately, that extension does not provide the foreign agent any Unfortunately, that extension does not provide the foreign agent any
direct guarantee that the protocol is protected from replays, and direct guarantee that the protocol is protected from replays, and
does not allow for the use of CHAP [RFC1994] for authenticating does not allow for the use of CHAP [RFC1994] for authenticating
portable computer devices. In this specification, we define portable computer devices. In this specification, we define
extensions for the Mobile IP Agent Advertisements and the extensions for the Mobile IP Agent Advertisements and the
Registration Request that allow a foreign agent to a use challenge/ Registration Request that allow a foreign agent to a use
response mechanism to authenticate the mobile node. Furthermore, an challenge/response mechanism to authenticate the mobile node.
additional authentication extension, the Mobile-AAA authentication Furthermore, an additional authentication extension, the Mobile-AAA
extension, is provided so that a mobile node can supply credentials authentication extension, is provided so that a mobile node can
for authorization using commonly available AAA infrastructure supply credentials for authorization using commonly available AAA
elements. The foreign agent may be able to interact with an AAA infrastructure elements. The foreign agent may be able to interact
infrastructure (using protocols outside the scope of this document) with an AAA infrastructure (using protocols outside the scope of this
to obtain a secure indication that the mobile node is authorized to document) to obtain a secure indication that the mobile node is
use the local network resources. authorized to use the local network resources.
1.1 Terminology 1.1 Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119]. document are to be interpreted as described in RFC 2119 [RFC2119].
This document uses the term Security Parameters Index (SPI) as This document uses the term Security Parameters Index (SPI) as
defined in the base Mobile IP protocol specification [RFC3344]. All defined in the base Mobile IP protocol specification [RFC3344]. All
SPI values defined in this document refer to values for the SPI as SPI values defined in this document refer to values for the SPI as
skipping to change at page 6, line 17 skipping to change at page 6, line 17
This section defines a new extension to the Router Discovery Protocol This section defines a new extension to the Router Discovery Protocol
[RFC1256] for use by foreign agents that need to issue a challenge [RFC1256] for use by foreign agents that need to issue a challenge
for authenticating mobile nodes. for authenticating mobile nodes.
0 1 2 3 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 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Challenge ... | Type | Length | Challenge ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: The Mobile-Foreign Challenge Extension Figure 1: The Challenge Extension
Type: Type:
24 24
Length: Length:
The length of the Challenge value in bytes; SHOULD be at least The length of the Challenge value in bytes; SHOULD be at least
4 4
Challenge: Challenge:
A random value that SHOULD be at least 32 bits A random value that SHOULD be at least 32 bits
The Challenge extension, illustrated in Figure 1, is inserted in the The Challenge extension, illustrated in Figure 1, is inserted in the
skipping to change at page 8, line 52 skipping to change at page 8, line 52
If the mobile node does not have a security association with the If the mobile node does not have a security association with the
foreign agent, the mobile node MUST include the Mobile-AAA foreign agent, the mobile node MUST include the Mobile-AAA
Authentication extension as defined in Section 6 when it includes the Authentication extension as defined in Section 6 when it includes the
Mobile-Foreign Challenge extension. In addition, the mobile node Mobile-Foreign Challenge extension. In addition, the mobile node
SHOULD include the NAI extension [RFC2794], to enable the foreign SHOULD include the NAI extension [RFC2794], to enable the foreign
agent to make use of available verification infrastructure which agent to make use of available verification infrastructure which
requires this. The SPI field of the Mobile-AAA Authentication requires this. The SPI field of the Mobile-AAA Authentication
extension specifies the particular secret and algorithm (shared extension specifies the particular secret and algorithm (shared
between the mobile node and the verification infrastructure) that between the mobile node and the verification infrastructure) that
must be used to perform the authentication. If the SPI value is must be used to perform the authentication. If the SPI value is
chosen as CHAP_SPI or HMAC_CHAP_SPI (see Section 9), then the mobile chosen as CHAP_SPI (see Section 9), then the mobile node specifies
node specifies CHAP-style authentication [RFC1994] using MD5 CHAP-style authentication [RFC1994] using MD5 [RFC1321].
[RFC1321] or HMAC_MD5, respectively.
In either case, the Mobile-Foreign Challenge extension followed by In either case, the Mobile-Foreign Challenge extension followed by
one of the above specified authentication extensions MUST follow the one of the above specified authentication extensions MUST follow the
Mobile-Home Authentication extension, if present. Mobile-Home Authentication extension, if present.
A mobile node MAY include the Mobile-AAA Authentication extension in A mobile node MAY include the Mobile-AAA Authentication extension in
the Registration Request when the mobile node registers directly with the Registration Request when the mobile node registers directly with
its home agent (using a co-located care-of address). In this case, its home agent (using a co-located care-of address). In this case,
if the mobile node uses an SPI value of CHAP_SPI or HMAC_CHAP_SPI if the mobile node uses an SPI value of CHAP_SPI (Section 8) in the
(Section 8) in the MN-AAA Authentication extension, the mobile node MN-AAA Authentication extension, the mobile node MUST include the
MUST include the Mobile-Foreign Challenge extension prior to the Mobile-Foreign Challenge extension prior to the Mobile-AAA
Mobile-AAA Authentication extension. The mechanism used by the Authentication extension. The mechanism used by the mobile node to
mobile node to obtain the Challenge value in this case is outside the obtain the Challenge value in this case is outside the scope of this
scope of this document. document.
3.2 Foreign Agent Processing for Registration Requests 3.2 Foreign Agent Processing for Registration Requests
Upon receipt of the Registration Request, if the foreign agent has Upon receipt of the Registration Request, if the foreign agent has
issued a Challenge as part of its Agent Advertisements, and it does issued a Challenge as part of its Agent Advertisements, and it does
not have a security association with the mobile node, then the not have a security association with the mobile node, then the
foreign agent SHOULD check that the Mobile-Foreign Challenge foreign agent SHOULD check that the Mobile-Foreign Challenge
extension exists, and that it contains a challenge value previously extension exists, and that it contains a challenge value previously
unused by the mobile node. This ensures that the mobile node is not unused by the mobile node. This ensures that the mobile node is not
attempting to replay a previous advertisement and authentication. In attempting to replay a previous advertisement and authentication. In
skipping to change at page 15, line 27 skipping to change at page 15, line 27
0 1 2 3 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 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Subtype | Length | | Type | Subtype | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SPI | | SPI |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Authenticator ... | Authenticator ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: The Mobile-Foreign Challenge Extension Figure 3: The Generalized Mobile IP Authentication Extension
Type: Type:
36 (not skippable) (see [RFC3344]) 36 (not skippable) (see [RFC3344])
Subtype: Subtype:
A number assigned to identify the kind of endpoints or other A number assigned to identify the kind of endpoints or other
characteristics of the particular authentication strategy characteristics of the particular authentication strategy
Length: Length:
4 plus the number of bytes in the Authenticator; MUST be at 4 plus the number of bytes in the Authenticator; MUST be at
least 20. least 20.
SPI: SPI:
skipping to change at page 18, line 13 skipping to change at page 18, line 13
http://www.iana.org/numbers.html http://www.iana.org/numbers.html
8. SPIs for RADIUS AAA Servers 8. SPIs for RADIUS AAA Servers
Some AAA servers only admit a single security association, and thus Some AAA servers only admit a single security association, and thus
do not use the SPI numbers for Mobile IP authentication extensions do not use the SPI numbers for Mobile IP authentication extensions
for use when determining the security association that would be for use when determining the security association that would be
necessary for verifying the authentication information included with necessary for verifying the authentication information included with
the Authentication extension. the Authentication extension.
SPI numbers CHAP_SPI and HMAC_CHAP_SPI (see Section 9) are reserved SPI number CHAP_SPI (see Section 9) is reserved for indicating the
for indicating the following procedure for computing authentication following procedure for computing authentication data (called the
data (called the "authenticator"), which is used by many RADIUS "authenticator"), which is used by many RADIUS servers [RFC2138]
servers [RFC2138] today. today.
To compute the authenticator, apply MD5 [RFC1321] computed on the To compute the authenticator, apply MD5 [RFC1321] computed on the
following data, in the order shown: following data, in the order shown:
High-order byte from Challenge || Key || High-order byte from Challenge || Key ||
MD5(Preceding Mobile IP data || MD5(Preceding Mobile IP data ||
Type, Subtype (if present), Length, SPI) || Type, Subtype (if present), Length, SPI) ||
Least-order 237 bytes from Challenge Least-order 237 bytes from Challenge
where the Type, Length, SPI, and possibly Subtype, are the fields of where the Type, Length, SPI, and possibly Subtype, are the fields of
the authentication extension in use. For instance, all four of these the authentication extension in use. For instance, all four of these
fields would be in use when SPI == (CHAP_SPI or HMAC_CHAP_SPI) is fields would be in use when SPI == CHAP_SPI is used with the
used with the Generalized Authentication extension. The use of SPI Generalized Authentication extension. Since the RADIUS protocol
number HMAC_CHAP_SPI indicates the use of HMAC_MD5 instead of MD5 in cannot carry attributes of length greater than 253, the preceding
the above procedure. Since the RADIUS protocol cannot carry Mobile IP data, type, subtype (if present), length and SPI are hashed
attributes of length greater than 253, the preceding Mobile IP data, using MD5. Finally, the least significant 237 bytes of the challenge
type, subtype (if present), length and SPI are hashed using MD5. are concatenated. If the challenge has fewer than 238 bytes, this
Finally, the least significant 237 bytes of the challenge are
concatenated. If the challenge has fewer than 238 bytes, this
algorithm includes the high-order byte in the computation twice, but algorithm includes the high-order byte in the computation twice, but
ensures that the challenge is used exactly as is. Additional padding ensures that the challenge is used exactly as is. Additional padding
is never used to increase the length of the challenge; the input data is never used to increase the length of the challenge; the input data
is allowed to be shorter than 237 bytes long. is allowed to be shorter than 237 bytes long.
9. Configurable Parameters 9. Configurable Parameters
Every Mobile IP agent supporting the extensions defined in this Every Mobile IP agent supporting the extensions defined in this
document SHOULD be able to configure each parameter in the following document SHOULD be able to configure each parameter in the following
table. Each table entry contains the name of the parameter, the table. Each table entry contains the name of the parameter, the
default value, and the section of the document in which the parameter default value, and the section of the document in which the parameter
first appears. first appears.
+------------------+---------------+---------------------+ +------------------+---------------+---------------------+
| Parameter Name | Default Value | Section of Document | | Parameter Name | Default Value | Section of Document |
+------------------+---------------+---------------------+ +------------------+---------------+---------------------+
| CHALLENGE_WINDOW | 2 | 3.2 | | CHALLENGE_WINDOW | 2 | 3.2 |
| | | | | | | |
| CHAP_SPI | 2 | 8 | | CHAP_SPI | 2 | 8 |
| | | |
| HMAC_CHAP_SPI | 3 | 8 |
+------------------+---------------+---------------------+ +------------------+---------------+---------------------+
Table 1: Configurable Parameters Table 1: Configurable Parameters
Note that CHALLENGE_WINDOW SHOULD be at least 2. This makes it far Note that CHALLENGE_WINDOW SHOULD be at least 2. This makes it far
less likely that mobile nodes will register using a Challenge value less likely that mobile nodes will register using a Challenge value
that is outside the set of values allowable by the foreign agent. that is outside the set of values allowable by the foreign agent.
10. Error Values 10. Error Values
skipping to change at page 26, line 5 skipping to change at page 25, line 23
List of the changes for draft-ietf-mip4-rfc3012bis-01: List of the changes for draft-ietf-mip4-rfc3012bis-01:
o Minor editorial changes are made through out the document. o Minor editorial changes are made through out the document.
o Added reference of FA Error extension in the References section o Added reference of FA Error extension in the References section
and also updated relevant text in section 3.2 and section 11. and also updated relevant text in section 3.2 and section 11.
List of the changes for draft-ietf-mip4-rfc3012bis-02: List of the changes for draft-ietf-mip4-rfc3012bis-02:
o Minor editorial changes are made in Appendix C and Appendix D. o Minor editorial changes are made in Appendix C and Appendix D.
o Updated Boilerplate. o Updated Boilerplate.
List of the changes for draft-ietf-mip4-rfc3012bis-03:
o Removed HMAC_MD5_SPI support from section 3.1, 8 and 9.
o Corrected figure titles 1 and 3.
Appendix B. Verification Infrastructure Appendix B. Verification Infrastructure
The Challenge extensions in this protocol specification are expected The Challenge extensions in this protocol specification are expected
to be useful to help the foreign agent manage connectivity for to be useful to help the foreign agent manage connectivity for
visiting mobile nodes, even in situations where the foreign agent visiting mobile nodes, even in situations where the foreign agent
does not have any security association with the mobile node or the does not have any security association with the mobile node or the
mobile node's home agent. In order to carry out the necessary mobile node's home agent. In order to carry out the necessary
authentication, it is expected that the foreign agent will need the authentication, it is expected that the foreign agent will need the
assistance of external administrative systems, which have come to be assistance of external administrative systems, which have come to be
called AAA systems. For the purposes of this document, we call the called AAA systems. For the purposes of this document, we call the
skipping to change at page 32, line 16 skipping to change at page 32, line 16
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2138] Rigney, C., Rigney, C., Rubens, A., Simpson, W. and S. [RFC2138] Rigney, C., Rigney, C., Rubens, A., Simpson, W. and S.
Willens, "Remote Authentication Dial In User Service Willens, "Remote Authentication Dial In User Service
(RADIUS)", RFC 2138, April 1997. (RADIUS)", RFC 2138, April 1997.
[RFC2794] Calhoun, P. and C. Perkins, "Mobile IP Network Access [RFC2794] Calhoun, P. and C. Perkins, "Mobile IP Network Access
Identifier Extension for IPv4", RFC 2794, March 2000. Identifier Extension for IPv4", RFC 2794, March 2000.
[RFC3012] Perkins, C. and P. Calhoun, "Mobile IPv4 Challenge/ [RFC3012] Perkins, C. and P. Calhoun, "Mobile IPv4
Response Extensions", RFC 3012, November 2000. Challenge/Response Extensions", RFC 3012, November 2000.
[RFC3344] Perkins, C., "IP Mobility Support for IPv4", RFC 3344, [RFC3344] Perkins, C., "IP Mobility Support for IPv4", RFC 3344,
August 2002. August 2002.
Authors' Addresses Authors' Addresses
Charles E. Perkins Charles E. Perkins
Nokia Research Center Nokia Research Center
Communications Systems Lab Communications Systems Lab
313 Fairchild Drive 313 Fairchild Drive
 End of changes. 

This html diff was produced by rfcdiff 1.23, available from http://www.levkowetz.com/ietf/tools/rfcdiff/