draft-ietf-mip4-rfc3012bis-03.txt   draft-ietf-mip4-rfc3012bis-04.txt 
Network Working Group Charles E. Perkins Network Working Group Charles E. Perkins
Internet-Draft Nokia Research Center Internet-Draft Nokia Research Center
Expires: June 2, 2005 Pat R. Calhoun Expires: December 19, 2005 Pat R. Calhoun
Black Storm Networks Black Storm Networks
Jayshree. Bharatia Jayshree. Bharatia
Nortel Networks Nortel Networks
December 2, 2004 June 17, 2005
Mobile IPv4 Challenge/Response Extensions (revised) Mobile IPv4 Challenge/Response Extensions (revised)
draft-ietf-mip4-rfc3012bis-03.txt draft-ietf-mip4-rfc3012bis-04.txt
Status of this Memo Status of this Memo
This document is an Internet-Draft and is subject to all provisions By submitting this Internet-Draft, each author represents that any
of section 3 of RFC 3667. By submitting this Internet-Draft, each applicable patent or other IPR claims of which he or she is aware
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which he or she is aware have been or will be disclosed, and any of aware will be disclosed, in accordance with Section 6 of BCP 79.
which he or she become aware will be disclosed, in accordance with
RFC 3668.
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Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2004). Copyright (C) The Internet Society (2005).
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 3, line 17 skipping to change at page 3, line 17
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1 Terminology . . . . . . . . . . . . . . . . . . . . . . . 4 1.1 Terminology . . . . . . . . . . . . . . . . . . . . . . . 4
2. Mobile IP Agent Advertisement Challenge Extension . . . . . . 6 2. Mobile IP Agent Advertisement Challenge Extension . . . . . . 6
2.1 Handling of Solicited Agent Advertisements . . . . . . . . 6 2.1 Handling of Solicited Agent Advertisements . . . . . . . . 6
3. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . 8 3. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3.1 Mobile Node Processing for Registration Requests . . . . . 8 3.1 Mobile Node Processing for Registration Requests . . . . . 8
3.2 Foreign Agent Processing for Registration Requests . . . . 9 3.2 Foreign Agent Processing for Registration Requests . . . . 9
3.3 Foreign Agent Processing for Registration Replies . . . . 11 3.3 Foreign Agent Processing for Registration Replies . . . . 11
3.4 Home Agent Processing for the Challenge Extensions . . . . 12 3.4 Home Agent Processing for the Challenge Extensions . . . . 12
3.5 Mobile Node Processing for Registration Replies . . . . . 12 3.5 Mobile Node Processing for Registration Replies . . . . . 12
4. Mobile-Foreign Challenge Extension . . . . . . . . . . . . . . 14 4. Mobile-Foreign Challenge Extension . . . . . . . . . . . . . . 15
5. Generalized Mobile IP Authentication Extension . . . . . . . . 15 5. Generalized Mobile IP Authentication Extension . . . . . . . . 16
6. Mobile-AAA Authentication subtype . . . . . . . . . . . . . . 16 6. Mobile-AAA Authentication subtype . . . . . . . . . . . . . . 18
7. Reserved SPIs for Mobile IP . . . . . . . . . . . . . . . . . 17 7. Reserved SPIs for Mobile IP . . . . . . . . . . . . . . . . . 19
8. SPIs for RADIUS AAA Servers . . . . . . . . . . . . . . . . . 18 8. SPIs for RADIUS AAA Servers . . . . . . . . . . . . . . . . . 20
9. Configurable Parameters . . . . . . . . . . . . . . . . . . . 19 9. Configurable Parameters . . . . . . . . . . . . . . . . . . . 21
10. Error Values . . . . . . . . . . . . . . . . . . . . . . . . 20 10. Error Values . . . . . . . . . . . . . . . . . . . . . . . . 22
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . 21 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . 23
12. Security Considerations . . . . . . . . . . . . . . . . . . 22 12. Security Considerations . . . . . . . . . . . . . . . . . . 24
13. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . 23 13. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . 25
A. Change History . . . . . . . . . . . . . . . . . . . . . . . . 24 14. Normative References . . . . . . . . . . . . . . . . . . . . 25
B. Verification Infrastructure . . . . . . . . . . . . . . . . . 26 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 26
A. Change History . . . . . . . . . . . . . . . . . . . . . . . . 27
B. Verification Infrastructure . . . . . . . . . . . . . . . . . 30
C. Message Flow for FA Challenge Messaging with Mobile-AAA C. Message Flow for FA Challenge Messaging with Mobile-AAA
Extension . . . . . . . . . . . . . . . . . . . . . . . . . . 28 Extension . . . . . . . . . . . . . . . . . . . . . . . . . . 32
D. Message Flow for FA Challenge Messaging with MN-FA D. Message Flow for FA Challenge Messaging with MN-FA
Authentication . . . . . . . . . . . . . . . . . . . . . . . . 29 Authentication . . . . . . . . . . . . . . . . . . . . . . . . 34
E. Foreign Agent Algorithm for Tracking Used Challenges . . . . . 30 E. Foreign Agent Algorithm for Tracking Used Challenges . . . . . 35
14. Normative References . . . . . . . . . . . . . . . . . . . . 31 Intellectual Property and Copyright Statements . . . . . . . . 37
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 32
Intellectual Property and Copyright Statements . . . . . . . . 33
1. Introduction 1. Introduction
Mobile IP defines the Mobile-Foreign Authentication extension to Mobile IP defines the Mobile-Foreign Authentication extension to
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 Registration Request that allow a foreign agent to use challenge/
challenge/response mechanism to authenticate the mobile node. response mechanism to authenticate the mobile node. Furthermore, an
Furthermore, an additional authentication extension, the Mobile-AAA additional authentication extension, the Mobile-AAA authentication
authentication extension, is provided so that a mobile node can extension, is provided so that a mobile node can supply credentials
supply credentials for authorization using commonly available AAA for authorization using commonly available AAA infrastructure
infrastructure elements. The foreign agent may be able to interact elements. The foreign agent may be able to interact with an AAA
with an AAA infrastructure (using protocols outside the scope of this infrastructure (using protocols outside the scope of this document)
document) to obtain a secure indication that the mobile node is to obtain a secure indication that the mobile node is authorized to
authorized to use the local network resources. 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
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"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
defined in that specification. defined in that specification.
The following additional terminology is used in addition to that The following additional terminology is used in addition to that
defined in [RFC3344]: defined in [RFC3344]:
previously used challenge: previously used challenge:
The challenge is previously used challenge if the mobile node
The challenge is a previously used challenge if the mobile node
sent the same challenge to the foreign agent in a previous sent the same challenge to the foreign agent in a previous
Registration Request, and that previous Registration Request Registration Request, and that previous Registration Request
passed all validity checks performed by the foreign agent. The passed all validity checks performed by the foreign agent. The
foreign agent may not be able to keep records for all foreign agent may not be able to keep records for all
previously used challenges, but see Section 3.2 for minimal previously used challenges, but see Section 3.2 for minimal
requirements. requirements.
security association: security association:
A "mobility security association", as defined in [RFC3344]. A "mobility security association", as defined in [RFC3344].
unknown challenge: unknown challenge:
Any challenge from a particular mobile node that the foreign Any challenge from a particular mobile node that the foreign
agent has no record of having put either into one of its recent agent has no record of having put either into one of its recent
Agent Advertisements or into a registration reply message to Agent Advertisements or into a registration reply message to
that mobile node. that mobile node.
unused challenge: unused challenge:
A challenge that has not been already accepted by the foreign A challenge that has not been already accepted by the foreign
agent from the mobile node in the Registration Request -- i.e., agent from the mobile node in the Registration Request -- i.e.,
a challenge that is neither unknown nor previously used. a challenge that is neither unknown nor previously used.
2. Mobile IP Agent Advertisement Challenge Extension 2. Mobile IP Agent Advertisement Challenge Extension
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.
skipping to change at page 8, line 36 skipping to change at page 8, line 36
foreign agent, it SHOULD include the Challenge value in its foreign agent, it SHOULD include the Challenge value in its
Registration Request message. Registration Request message.
If the mobile node has a security association with the Foreign Agent, If the mobile node has a security association with the Foreign Agent,
it MUST include a Mobile-Foreign Authentication extension in its it MUST include a Mobile-Foreign Authentication extension in its
Registration Request message, according to the base Mobile IP Registration Request message, according to the base Mobile IP
specification [RFC3344]. When the Registration Request contains the specification [RFC3344]. When the Registration Request contains the
Mobile-Foreign Challenge extension specified in Section 4, the Mobile-Foreign Challenge extension specified in Section 4, the
Mobile-Foreign Authentication MUST follow the Challenge extension in Mobile-Foreign Authentication MUST follow the Challenge extension in
the Registration Request. The mobile node MAY also include the the Registration Request. The mobile node MAY also include the
Mobile-AAA Authentication extension. If both, the Mobile-Foreign Mobile-AAA Authentication extension. If both the Mobile-Foreign
Authentication and the Mobile-AAA Authentication extensions are Authentication and the Mobile-AAA Authentication extensions are
present, the Mobile-Foreign Challenge extension MUST precede the present, the Mobile-Foreign Challenge extension MUST precede the
Mobile-AAA Authentication extension and the Mobile-AAA Authentication Mobile-AAA Authentication extension and the Mobile-AAA Authentication
extension MUST precede the Mobile-Foreign Authentication extension. extension MUST precede the Mobile-Foreign Authentication extension.
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
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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
this case, if the Registration Request does not include a challenge this case, if the Registration Request does not include a challenge
extension, the foreign agent MUST include FA Error extension (defined extension, the foreign agent MUST send a Registration Reply with the
in [FAERR]) in the Registration Reply message with Status code set to Code field set to set to MISSING_CHALLENGE. In this document,
MISSING_CHALLENGE. whenever the foreign agent is required to reject a Registration
Request, it MUST put the given code in the usual Code field of the
A foreign agent that sends Agent Advertisements containing a Registration Reply, unless the Registration Reply has already been
Challenge value MAY send a Registration Reply message with a received from the home agent. In this case the foreign agent MUST
MISSING_CHALLENGE error if the mobile node sends a Registration preserve the value of the Code field set by the home agent and MUST
Request with a Mobile-Foreign Authentication extension without put its own rejection code only in the Status field of the FA Error
including a Challenge. In other words, such a foreign agent MAY extension (defined in [FAERR]).
refuse to process a Registration Request from the mobile node unless
the request contains an unused Challenge.
If a mobile node retransmits a Registration Request with the same If a mobile node retransmits a Registration Request with the same
Challenge extension, and the foreign agent still has a pending Challenge extension, and the foreign agent still has a pending
Registration Request record in effect for the mobile node, then the Registration Request record in effect for the mobile node, then the
foreign agent forwards the Registration Request to the Home Agent foreign agent forwards the Registration Request to the Home Agent
again. The foreign agent SHOULD check that the mobile node is again. The foreign agent SHOULD check that the mobile node is
actually performing a retransmission, by verifying that the relevant actually performing a retransmission, by verifying that the relevant
fields of the retransmitted request (including, if present, the fields of the retransmitted request (including, if present, the
mobile node NAI Extension [RFC2794]) are the same as represented in mobile node NAI Extension [RFC2794]) are the same as represented in
the visitor list entry for the pending Registration Request (section the visitor list entry for the pending Registration Request (section
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If the foreign agent does not remove the Challenge extension, then If the foreign agent does not remove the Challenge extension, then
the foreign agent SHOULD store the Challenge value as part of the the foreign agent SHOULD store the Challenge value as part of the
pending registration request list [RFC3344]. Also, if the pending registration request list [RFC3344]. Also, if the
Registration Reply coming from the home agent does not include the Registration Reply coming from the home agent does not include the
Challenge Extension, the foreign agent SHOULD NOT reject the Challenge Extension, the foreign agent SHOULD NOT reject the
Registration Request message. If the Challenge Extension is present Registration Request message. If the Challenge Extension is present
in the Registration Reply, it MUST be the same Challenge value that in the Registration Reply, it MUST be the same Challenge value that
was included in the Registration Request. If the Challenge value was included in the Registration Request. If the Challenge value
differs in the Registration Reply received from the home agent, the differs in the Registration Reply received from the home agent, the
foreign agent MUST insert a rejection Code value MISSING_CHALLENGE in foreign agent MUST insert an FA Error extension with Status value
the Registration Reply sent to the mobile node (see Section 10). HA_WRONG_CHALLENGE in the Registration Reply sent to the mobile node
(see Section 10).
If the foreign agent does remove the Challenge extension and If the foreign agent does remove the Challenge extension and
applicable authentication from the Registration Request message, then applicable authentication from the Registration Request message, then
it SHOULD insert the Identification field from the Registration it SHOULD insert the Identification field from the Registration
Request message along with its record-keeping information about the Request message along with its record-keeping information about the
particular mobile node in order to protect against replays. particular mobile node in order to protect against replays.
3.3 Foreign Agent Processing for Registration Replies 3.3 Foreign Agent Processing for Registration Replies
The foreign agent SHOULD include a new Mobile-Foreign Challenge The foreign agent SHOULD include a new Mobile-Foreign Challenge
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A mobile node MUST be prepared to use a challenge from a unicast or A mobile node MUST be prepared to use a challenge from a unicast or
multicast Agent Advertisement in lieu of one returned in a multicast Agent Advertisement in lieu of one returned in a
Registration Reply, and MUST solicit for one if it has not already Registration Reply, and MUST solicit for one if it has not already
received one in a Registration Reply. received one in a Registration Reply.
If the foreign agent receives a Registration Reply with the Code If the foreign agent receives a Registration Reply with the Code
value HA_BAD_AAA_AUTH, it MUST be relayed to the mobile node. value HA_BAD_AAA_AUTH, it MUST be relayed to the mobile node.
3.4 Home Agent Processing for the Challenge Extensions 3.4 Home Agent Processing for the Challenge Extensions
If the home agent receives a Registration Request with the If the home agent receives a Registration Request with the Mobile-
Mobile-Foreign Challenge extension, and recognizes the extension, the Foreign Challenge extension, and recognizes the extension, the home
home agent MUST include the Challenge extension in the Registration agent MUST include the Challenge extension in the Registration Reply.
Reply. The Challenge Extension MUST be placed after the Mobile-Home The Challenge Extension MUST be placed after the Mobile-Home
authentication extension, and the extension SHOULD be authenticated authentication extension, and the extension SHOULD be authenticated
by a Foreign-Home Authentication extension. by a Foreign-Home Authentication extension.
The home agent MAY receive a Registration Request with the Mobile-AAA The home agent MAY receive a Registration Request with the Mobile-AAA
Authentication extension. If the Mobile-AAA Authentication extension Authentication extension. If the Mobile-AAA Authentication extension
is used by the home agent as an authorization-enabling extension and is used by the home agent as an authorization-enabling extension and
the verification fails due to incorrect authenticator, the home agent the verification fails due to incorrect authenticator, the home agent
MAY reject the Registration Reply with the error code MAY reject the Registration Reply with the error code
HA_BAD_AAA_AUTH. HA_BAD_AAA_AUTH.
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STALE_CHALLENGE: If the foreign agent receives a Registration Request STALE_CHALLENGE: If the foreign agent receives a Registration Request
with a Challenge extension containing a Challenge value previously with a Challenge extension containing a Challenge value previously
used by that mobile node, the mobile node MAY receive a Registration used by that mobile node, the mobile node MAY receive a Registration
Reply to the mobile node containing the Code value STALE_CHALLENGE. Reply to the mobile node containing the Code value STALE_CHALLENGE.
In such instances, the mobile node MUST use a new Challenge value in In such instances, the mobile node MUST use a new Challenge value in
next Registration Request, obtained either from an Agent next Registration Request, obtained either from an Agent
Advertisement, or from a Challenge extension to the Registration Advertisement, or from a Challenge extension to the Registration
Reply containing the error. Reply containing the error.
HA_WRONG_CHALLENGE: This error is sent by the foreign agent if the
Registration Reply from the home agent contains a different Challenge
value from the one included in the Registration Request.
4. Mobile-Foreign Challenge Extension 4. Mobile-Foreign Challenge Extension
This section specifies a new Mobile IP Registration extension that is This section specifies a new Mobile IP Registration extension that is
used to satisfy a Challenge in an Agent Advertisement. The Challenge used to satisfy a Challenge in an Agent Advertisement. The Challenge
extension to the Registration Request message is used to indicate the extension to the Registration Request message is used to indicate the
challenge that the mobile node is attempting to satisfy. challenge that the mobile node is attempting to satisfy.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
skipping to change at page 16, line 20 skipping to change at page 18, line 20
Registration Request. This extension MAY co-exist in the same Registration Request. This extension MAY co-exist in the same
Registration Request with Authentication extensions defined for Registration Request with Authentication extensions defined for
Mobile IP Registration by [RFC3344]. If the mobile node does not Mobile IP Registration by [RFC3344]. If the mobile node does not
include a Mobile-Foreign Authentication [RFC3344] extension, then it include a Mobile-Foreign Authentication [RFC3344] extension, then it
MUST include the Mobile-AAA Authentication extension whenever the MUST include the Mobile-AAA Authentication extension whenever the
Challenge extension is present. If both are present, the Mobile-AAA Challenge extension is present. If both are present, the Mobile-AAA
Authentication extension MUST precede the Mobile-Foreign Authentication extension MUST precede the Mobile-Foreign
Authentication extension. Authentication extension.
If the Mobile-AAA Authentication extension is present, then the If the Mobile-AAA Authentication extension is present, then the
Registration Message sent by the mobile node MUST contain the Registration Message sent by the mobile node MUST contain the Mobile-
Mobile-Home Authentication extension [RFC3344] if it shares a Home Authentication extension [RFC3344] if it shares a security
security association with the home agent. If both are present, the association with the home agent. If both are present, the Mobile-
Mobile-Home Authentication Extension MUST appear prior to the Home Authentication Extension MUST appear prior to the Mobile-AAA
Mobile-AAA Authentication extension. The corresponding response MUST Authentication extension. The corresponding response MUST include
include the Mobile-Home Authentication Extension, and MUST NOT the Mobile-Home Authentication Extension, and MUST NOT include the
include the Mobile-AAA Authentication Extension. Mobile-AAA Authentication Extension.
The default algorithm for computation of the authenticator is The default algorithm for computation of the authenticator is HMAC-
HMAC-MD5 [RFC2104] computed on the following data, in the order MD5 [RFC2104] computed on the following data, in the order shown:
shown:
Preceding Mobile IP data || Type, Subtype, Length, SPI Preceding Mobile IP data || Type, Subtype, Length, SPI
where the Type, Length, Subtype, and SPI are as shown in Section 5. where the Type, Length, Subtype, and SPI are as shown in Section 5.
The resulting function call, as described in [RFC2104], would be: The resulting function call, as described in [RFC2104], would be:
hmac_md5(data, datalen, Key, KeyLength, authenticator); hmac_md5(data, datalen, Key, KeyLength, authenticator);
Each mobile node MUST support the ability to produce the Each mobile node MUST support the ability to produce the
authenticator by using HMAC-MD5 as shown. Just as with Mobile IP, it authenticator by using HMAC-MD5 as shown. Just as with Mobile IP, it
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| | | | | | | |
| BAD_AUTHENTICATION | 67 | 3.2 - also see [RFC3344] | | BAD_AUTHENTICATION | 67 | 3.2 - also see [RFC3344] |
| | | | | | | |
| MISSING_CHALLENGE | 105 | 3.1,3.2 | | MISSING_CHALLENGE | 105 | 3.1,3.2 |
| | | | | | | |
| STALE_CHALLENGE | 106 | 3.2 | | STALE_CHALLENGE | 106 | 3.2 |
| | | | | | | |
| FA_BAD_AAA_AUTH | TBD | 3.2 | | FA_BAD_AAA_AUTH | TBD | 3.2 |
| | | | | | | |
| HA_BAD_AAA_AUTH | TBD | 3.4 | | HA_BAD_AAA_AUTH | TBD | 3.4 |
| | | |
| HA_WRONG_CHALLENGE | TBD | 3.2 |
+--------------------+-------+--------------------------+ +--------------------+-------+--------------------------+
Table 2: Error Values Table 2: Error Values
11. IANA Considerations 11. IANA Considerations
All protocol values in this specification are to be the same as All protocol values in this specification are to be the same as
defined in RFC 3012 [RFC3012]. Additionaly, new error codes defined in RFC 3012 [RFC3012]. Additionaly, new error codes
FA_BAD_AAA_AUTH and HA_BAD_AAA_AUTH are defined by this document. FA_BAD_AAA_AUTH, HA_BAD_AAA_AUTH, and HA_WRONG_CHALLENGE are defined
The Status code list for the FA Error extension defined in [FAERR] is by this document. Among these, HA_WRONG_CHALLENGE may appear in the
extended with the new Status code MISSING_CHALLENGE along with the Status code of the FA Error extension defined in [FAERR].
new sub-type (TBD) for the protocol extension specified in this
document.
12. Security Considerations 12. Security Considerations
In the event that a malicious mobile node attempts to replay the In the event that a malicious mobile node attempts to replay the
authenticator for an old Mobile-Foreign Challenge, the foreign agent authenticator for an old Mobile-Foreign Challenge, the foreign agent
would detect it since the agent always checks whether it has recently would detect it since the agent always checks whether it has recently
advertised the Challenge (see Section 3.2). Allowing mobile nodes advertised the Challenge (see Section 3.2). Allowing mobile nodes
with different IP addresses or NAIs to use the same Challenge value with different IP addresses or NAIs to use the same Challenge value
does not represent a security vulnerability, because the does not represent a security vulnerability, because the
authentication data provided by the mobile node will be computed over authentication data provided by the mobile node will be computed over
skipping to change at page 22, line 32 skipping to change at page 24, line 32
assuredly not replayed from any earlier registration. assuredly not replayed from any earlier registration.
Section 8 (SPI For RADIUS AAA Servers) defines a method of computing Section 8 (SPI For RADIUS AAA Servers) defines a method of computing
the Generalized Mobile IP Authentication Extension's authenticator the Generalized Mobile IP Authentication Extension's authenticator
field using MD5 in a manner that is consistent with RADIUS [RFC2138]. field using MD5 in a manner that is consistent with RADIUS [RFC2138].
The use of MD5 in the method described in Section 8 is less secure The use of MD5 in the method described in Section 8 is less secure
than HMAC-MD5 [RFC2104], and should be avoided whenever possible. than HMAC-MD5 [RFC2104], and should be avoided whenever possible.
Note that an active attacker may try to prevent successful Note that an active attacker may try to prevent successful
registrations by sending a large number of Agent Solicitations or registrations by sending a large number of Agent Solicitations or
bogus Registration Requests, each of which could cause the FA to bogus Registration Requests, each of which could cause the foreign
respond with a fresh challenge, invalidating the challenge that the agent to respond with a fresh challenge, invalidating the challenge
MN is currently trying to use. To prevent such attacks, the FA MUST that the MN is currently trying to use. To prevent such attacks, the
NOT invalidate previously unused challenges when responding to foreign agent MUST NOT invalidate previously unused challenges when
unauthenticated Registration Requests or Agent Solicitations. In responding to unauthenticated Registration Requests or Agent
addition, the FA MUST NOT allocate new storage when responding to Solicitations. In addition, the foreign agent MUST NOT allocate new
such messages, because this would also create the possibility of storage when responding to such messages, because this would also
denial of service. create the possibility of denial of service.
13. Acknowledgments 13. Acknowledgments
The authors would like to thank Tom Hiller, Mark Munson, the TIA The authors would like to thank Tom Hiller, Mark Munson, the TIA
TR45-6 WG, Gabriel Montenegro, Vipul Gupta, Pete McCann, Robert TR45-6 WG, Gabriel Montenegro, Vipul Gupta, Pete McCann, Robert
Marks, Ahmad Muhanna, and Luca Salgarelli for their useful Marks, Ahmad Muhanna, and Luca Salgarelli for their useful
discussions. A recent draft by Mohamed Khalil, Raja Narayanan, Emad discussions. A recent draft by Mohamed Khalil, Raja Narayanan, Emad
Qaddoura, and Haseeb Akhtar has also suggested the definition of a Qaddoura, and Haseeb Akhtar has also suggested the definition of a
generalized authentication extension similar to the specification generalized authentication extension similar to the specification
contained in Section 5. contained in Section 5.
14. Normative References
[FAERR] Perkins, C., "Foreign Agent Error Extension for Mobile
IPv4", draft-perkins-mip4-faerr-00.txt (work in progress),
January 2004.
[RFC1256] Deering, S., "ICMP Router Discovery Messages", RFC 1256,
September 1991.
[RFC1321] Rivest, R., "The MD5 Message-Digest Algorithm", RFC 1321,
April 1992.
[RFC1750] Eastlake, D., Crocker, S., and J. Schiller, "Randomness
Recommendations for Security", RFC 1750, December 1994.
[RFC1994] Simpson, W., "PPP Challenge Handshake Authentication
Protocol (CHAP)", RFC 1994, August 1996.
[RFC2104] Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed-
Hashing for Message Authentication", RFC 2104,
February 1997.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2138] Rigney, C., Rigney, C., Rubens, A., Simpson, W., and S.
Willens, "Remote Authentication Dial In User Service
(RADIUS)", RFC 2138, April 1997.
[RFC2794] Calhoun, P. and C. Perkins, "Mobile IP Network Access
Identifier Extension for IPv4", RFC 2794, March 2000.
[RFC3012] Perkins, C. and P. Calhoun, "Mobile IPv4 Challenge/
Response Extensions", RFC 3012, November 2000.
[RFC3344] Perkins, C., "IP Mobility Support for IPv4", RFC 3344,
August 2002.
Authors' Addresses
Charles E. Perkins
Nokia Research Center
Communications Systems Lab
313 Fairchild Drive
Mountain View, California 94043
Fax: +1 650 625-2502
Email: charles.perkins@nokia.com
Pat R. Calhoun
Black Storm Networks
110 Nortech Parkway
San Jose, CA 95134
Fax: +1 720-293-7501
Email: pcalhoun@diameter.org
Jayshree Bharatia
Nortel Networks
2221, Lakeside Blvd
Richardson, TX 75082
Fax: +1 972-684-3775
Email: jayshree@nortelnetworks.com
Appendix A. Change History Appendix A. Change History
List of the changes for draft-ietf-mobileip-rfc3012bis-03: List of the changes for draft-ietf-mobileip-rfc3012bis-03:
o Foreign agent recommended to include a Challenge in every o Foreign agent recommended to include a Challenge in every
Registration Reply, so that mobile node can re-register without Registration Reply, so that mobile node can re-register without
waiting for an Advertisement. waiting for an Advertisement.
o Foreign agent MUST record applicable challenge values used by each o Foreign agent MUST record applicable challenge values used by each
mobile node. mobile node.
o Mobile node forbidden to use Challenge values which were o Mobile node forbidden to use Challenge values which were
advertised previous to the last Challenge value which it had used advertised previous to the last Challenge value which it had used
for a registration. for a registration.
o Terminology for stale challenge vs. unused challenge clarified. o Terminology for stale challenge vs. unused challenge clarified.
o Terminology for "valid" challenge deleted in favor of "unused o Terminology for "valid" challenge deleted in favor of "unused
challenge". challenge".
o Programming suggestion added as an appendix. o Programming suggestion added as an appendix.
List of the changes for draft-ietf-mobileip-rfc3012bis-04: List of the changes for draft-ietf-mobileip-rfc3012bis-04:
o The definition of "previously used challenge" is merged with o The definition of "previously used challenge" is merged with
"stale challenge" definition in section 1.1. "stale challenge" definition in section 1.1.
o Reference 7 is updated from RFC 3320 to RFC 3344 and reference 9 o Reference 7 is updated from RFC 3320 to RFC 3344 and reference 9
is updated from RFC 2138 to RFC 2865 in "Reference" section. is updated from RFC 2138 to RFC 2865 in "Reference" section.
o Reference to RFC 3344 is added in section 3. o Reference to RFC 3344 is added in section 3.
o HMAC_CHAP_SPI option is added for Generalized Mobile IP o HMAC_CHAP_SPI option is added for Generalized Mobile IP
Authentication extension. Upon receipt of HMAC_CHAP_SPI, HMAC-MD5 Authentication extension. Upon receipt of HMAC_CHAP_SPI, HMAC-MD5
is used instead of MD5 for computing the authenticator. is used instead of MD5 for computing the authenticator.
o Clarified processing of error messages at the mobile node (section o Clarified processing of error messages at the mobile node (section
3.1). 3.1).
o Modified text of section 2.1 and 3.2 for further clarity. o Modified text of section 2.1 and 3.2 for further clarity.
List of the changes for draft-ietf-mobileip-rfc3012bis-05: List of the changes for draft-ietf-mobileip-rfc3012bis-05:
o Added BAD_AAA_AUTHENTICATION_SET_BY_FA and o Added BAD_AAA_AUTHENTICATION_SET_BY_FA and
BAD_AAA_AUTHENTICATION_SET_BY_HA error codes to report BAD_AAA_AUTHENTICATION_SET_BY_HA error codes to report
authentication errors caused while processing Mobile-AAA authentication errors caused while processing Mobile-AAA
Authentication extension. Authentication extension.
o Processing of the Mobile-AAA Authentication extension is clarified o Processing of the Mobile-AAA Authentication extension is clarified
for the foreign agent and the home agent. for the foreign agent and the home agent.
o Co-existence of the Mobile-AAA Authentication extension in the o Co-existence of the Mobile-AAA Authentication extension in the
same Registration Request is made explicit. same Registration Request is made explicit.
o The situation in which the foreign agent sets MISSING_CHALLENGE is o The situation in which the foreign agent sets MISSING_CHALLENGE is
clarified further. clarified further.
o The use of Mobile-AAA Authentication Extension is allowed by the o The use of Mobile-AAA Authentication Extension is allowed by the
mobile node with co-located care-of-address. mobile node with co-located care-of-address.
List of the changes for draft-ietf-mip4-rfc3012bis-00: List of the changes for draft-ietf-mip4-rfc3012bis-00:
o Minor editorial changes are made through out the document. o Minor editorial changes are made through out the document.
o Added definition of "previously used challenge" and removed o Added definition of "previously used challenge" and removed
definition of "stale challenge" from section 1.1. definition of "stale challenge" from section 1.1.
o Renamed BAD_AAA_AUTHENTICATION_SET_BY_FA to FA_BAD_AAA_AUTH and o Renamed BAD_AAA_AUTHENTICATION_SET_BY_FA to FA_BAD_AAA_AUTH and
BAD_AAA_AUTHENTICATION_SET_BY_HA to HA_BAD_AAA_AUTH. BAD_AAA_AUTHENTICATION_SET_BY_HA to HA_BAD_AAA_AUTH.
o Defined an order of the Mobile-AAA Authentication extension o Defined an order of the Mobile-AAA Authentication extension
received with the authentication extension(s) defined in RFC 3344 received with the authentication extension(s) defined in RFC 3344
[RFC3344]. [RFC3344].
o Added protection against bogus Registration Reply and Agent o Added protection against bogus Registration Reply and Agent
Advertisement. Also, the processing of the Challenge is clarified Advertisement. Also, the processing of the Challenge is clarified
if it is received in the multicast/unicast Agent Advertisement. if it is received in the multicast/unicast Agent Advertisement.
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: List of the changes for draft-ietf-mip4-rfc3012bis-03:
o Removed HMAC_MD5_SPI support from section 3.1, 8 and 9. o Removed HMAC_MD5_SPI support from section 3.1, 8 and 9.
o Corrected figure titles 1 and 3. o Corrected figure titles 1 and 3.
List of the changes for draft-ietf-mip4-rfc3012bis-04:
o Clarified use of FA Error extension in section 3.2. Also,
editorial changes are made in 1, 1.1, 3.1 and 3.2 sections.
o Introduced HA_WRONG_CHALLENGE error code.
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 30, line 30 skipping to change at page 35, line 30
be deleted from the foreign agent's records, perhaps along with all be deleted from the foreign agent's records, perhaps along with all
other registration information for the mobile node if it is no longer other registration information for the mobile node if it is no longer
registered. registered.
In the program fragment, it is presumed that the foreign agent keeps In the program fragment, it is presumed that the foreign agent keeps
an array of advertised Challenges ("VALID_ADV_CHALLENGES"), a record an array of advertised Challenges ("VALID_ADV_CHALLENGES"), a record
of the last advertised challenge used by a mobile node, and also a of the last advertised challenge used by a mobile node, and also a
record of the last challenge provided to a mobile node in a record of the last challenge provided to a mobile node in a
Registration Reply or unicast Agent Advertisement. Registration Reply or unicast Agent Advertisement.
To meet the security obligations outlined in Section 12, the FA To meet the security obligations outlined in Section 12, the foreign
SHOULD use one of the already stored, previously unused challenges agent SHOULD use one of the already stored, previously unused
when responding to an unauthenticated Registration Request or Agent challenges when responding to an unauthenticated Registration Request
Solicitation. If none of the already stored challenges are or Agent Solicitation. If none of the already stored challenges are
previously unused, the FA SHOULD generate a new challenge, include it previously unused, the foreign agent SHOULD generate a new challenge,
in the response, and store it in the per-Mobile data structure. include it in the response, and store it in the per-Mobile data
structure.
current_chal := RegistrationRequest.challenge_extension_value current_chal := RegistrationRequest.challenge_extension_value
last_chal := mobile_node_record.last_used_adv_chal last_chal := mobile_node_record.last_used_adv_chal
if (current_chal == mobile_node_record.RegReply_challenge) { if (current_chal == mobile_node_record.RegReply_challenge) {
update (mobile_node_record, current_chal) update (mobile_node_record, current_chal)
return (OK) return (OK)
} }
else if (current_chal "among" VALID_ADV_CHALLENGES[]{ else if (current_chal "among" VALID_ADV_CHALLENGES[]{
if (last_chal "among" VALID_ADV_CHALLENGES[]) { if (last_chal "among" VALID_ADV_CHALLENGES[]) {
skipping to change at page 31, line 32 skipping to change at page 37, line 5
} }
else { else {
update (mobile_node_record, current_chal) update (mobile_node_record, current_chal)
return (OK) return (OK)
} }
} }
else { else {
send_error(UNKNOWN_CHALLENGE); send_error(UNKNOWN_CHALLENGE);
} }
14 Normative References
[FAERR] Perkins, C., "Foreign Agent Error Extension for Mobile
IPv4", draft-perkins-mip4-faerr-00.txt (work in progress),
January 2004.
[RFC1256] Deering, S., "ICMP Router Discovery Messages", RFC 1256,
September 1991.
[RFC1321] Rivest, R., "The MD5 Message-Digest Algorithm", RFC 1321,
April 1992.
[RFC1750] Eastlake, D., Crocker, S. and J. Schiller, "Randomness
Recommendations for Security", RFC 1750, December 1994.
[RFC1994] Simpson, W., "PPP Challenge Handshake Authentication
Protocol (CHAP)", RFC 1994, August 1996.
[RFC2104] Krawczyk, H., Bellare, M. and R. Canetti, "HMAC:
Keyed-Hashing for Message Authentication", RFC 2104,
February 1997.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2138] Rigney, C., Rigney, C., Rubens, A., Simpson, W. and S.
Willens, "Remote Authentication Dial In User Service
(RADIUS)", RFC 2138, April 1997.
[RFC2794] Calhoun, P. and C. Perkins, "Mobile IP Network Access
Identifier Extension for IPv4", RFC 2794, March 2000.
[RFC3012] Perkins, C. and P. Calhoun, "Mobile IPv4
Challenge/Response Extensions", RFC 3012, November 2000.
[RFC3344] Perkins, C., "IP Mobility Support for IPv4", RFC 3344,
August 2002.
Authors' Addresses
Charles E. Perkins
Nokia Research Center
Communications Systems Lab
313 Fairchild Drive
Mountain View, California 94043
Fax: +1 650 625-2502
EMail: charles.perkins@nokia.com
Pat R. Calhoun
Black Storm Networks
110 Nortech Parkway
San Jose, CA 95134
Fax: +1 720-293-7501
EMail: pcalhoun@diameter.org
Jayshree Bharatia
Nortel Networks
2221, Lakeside Blvd
Richardson, TX 75082
Fax: +1 972-684-3775
EMail: jayshree@nortelnetworks.com
Intellectual Property Statement Intellectual Property Statement
The IETF takes no position regarding the validity or scope of any The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed to Intellectual Property Rights or other rights that might be claimed to
pertain to the implementation or use of the technology described in pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights this document or the extent to which any license under such rights
might or might not be available; nor does it represent that it has might or might not be available; nor does it represent that it has
made any independent effort to identify any such rights. Information made any independent effort to identify any such rights. Information
on the procedures with respect to rights in RFC documents can be on the procedures with respect to rights in RFC documents can be
found in BCP 78 and BCP 79. found in BCP 78 and BCP 79.
skipping to change at page 33, line 41 skipping to change at page 37, line 41
This document and the information contained herein are provided on an This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Copyright Statement Copyright Statement
Copyright (C) The Internet Society (2004). This document is subject Copyright (C) The Internet Society (2005). This document is subject
to the rights, licenses and restrictions contained in BCP 78, and to the rights, licenses and restrictions contained in BCP 78, and
except as set forth therein, the authors retain all their rights. except as set forth therein, the authors retain all their rights.
Acknowledgment Acknowledgment
Funding for the RFC Editor function is currently provided by the Funding for the RFC Editor function is currently provided by the
Internet Society. Internet Society.
 End of changes. 

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