Network Working Group K. Chowdhury
Internet-Draft Starent Networks
Intended status: Standards Track A. Lior
Expires: April 28, 2007 Bridgewater Systems
H. Tschofenig
Siemens
October 25, 2006
RADIUS Mobile IPv6 Support
draft-ietf-mip6-radius-01.txt
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Copyright (C) The Internet Society (2006).
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Abstract
A Mobile IPv6 node requires a home agent(HA) address, a home
address(HOA), and IPsec security association with its HA before it
can start utilizing Mobile IPv6 service. RFC 3775 requires that some
or all of these parameters are statically configured. Ongoing work
aims to make this information dynamically available to the mobile
node. An important aspect of the Mobile IPv6 bootstrapping solution
is to support interworking with existing authentication,
authorization and accounting (AAA) infrastructure. This document
defines new attributes to facilitate Mobile IPv6 bootstrapping via a
RADIUS infrastructure. This information exchange may take place as
part of the initial network access authentication procedure or as
part of a separate protocol exchange between the mobile node, the HA
and the AAA infrastructure.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. Solution Overview . . . . . . . . . . . . . . . . . . . . . . 6
3.1. Integrated Scenario . . . . . . . . . . . . . . . . . . . 6
3.2. Split Scenario . . . . . . . . . . . . . . . . . . . . . . 7
4. RADIUS Attribute Overview . . . . . . . . . . . . . . . . . . 9
4.1. MIP6-HA Attribute . . . . . . . . . . . . . . . . . . . . 9
4.2. MIP6-HA-FQDN Attribute . . . . . . . . . . . . . . . . . . 9
4.3. MIP6-HL-Prefix Attribute . . . . . . . . . . . . . . . . . 9
4.4. MIP6-HOA Attribute . . . . . . . . . . . . . . . . . . . . 9
4.5. MIP6-DNS-MO Attribute . . . . . . . . . . . . . . . . . . 9
5. RADIUS attributes . . . . . . . . . . . . . . . . . . . . . . 10
5.1. MIP6-HA Attribute . . . . . . . . . . . . . . . . . . . . 10
5.2. MIP6-HA-FQDN Attribute . . . . . . . . . . . . . . . . . . 11
5.3. MIP6-HL-Prefix Attribute . . . . . . . . . . . . . . . . . 11
5.4. MIP6-HOA Attribute . . . . . . . . . . . . . . . . . . . . 12
5.5. MIP6-DNS-MO Attribute . . . . . . . . . . . . . . . . . . 13
6. Message Flows . . . . . . . . . . . . . . . . . . . . . . . . 16
6.1. Integrated Scenario (MSA=ASA) . . . . . . . . . . . . . . 16
6.1.1. HA allocation in the MSP . . . . . . . . . . . . . . . 16
6.1.2. HA allocation in the ASP (visited network) . . . . . . 17
6.2. Split Scenario (MSA!=ASA) . . . . . . . . . . . . . . . . 18
6.2.1. Mobile Service Provider and Mobile Service
Authorizer are the same entity. . . . . . . . . . . . 18
6.2.2. Mobile Service Provider and Mobile Service
Authorizer are different entities. . . . . . . . . . . 20
7. Goals for the HA-AAA Interface . . . . . . . . . . . . . . . . 21
7.1. General Goals . . . . . . . . . . . . . . . . . . . . . . 21
7.2. Service Authorization . . . . . . . . . . . . . . . . . . 21
7.3. Accounting . . . . . . . . . . . . . . . . . . . . . . . . 22
7.4. MN Authentication . . . . . . . . . . . . . . . . . . . . 22
7.5. Provisioning of Configuration Parameters . . . . . . . . . 22
8. Table of Attributes . . . . . . . . . . . . . . . . . . . . . 23
9. Diameter Considerations . . . . . . . . . . . . . . . . . . . 24
10. Security Considerations . . . . . . . . . . . . . . . . . . . 25
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 26
12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 27
13. References . . . . . . . . . . . . . . . . . . . . . . . . . . 28
13.1. Normative References . . . . . . . . . . . . . . . . . . . 28
13.2. Informative References . . . . . . . . . . . . . . . . . . 28
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 30
Intellectual Property and Copyright Statements . . . . . . . . . . 31
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1. Introduction
Mobile IPv6 specification [5] requires a Mobile Node (MN) to perform
registration with a HA with information about its current point of
attachment (Care-of Address). The HA creates and maintains binding
between the MN's HOA and the MN's Care-of Address.
In order to register with a HA, the MN needs to know some information
such as, the Home Link prefix, the HA Address, the HOA, the Home Link
prefix Length and security related information in order to secure the
Binding Update.
The aforementioned set of information may be statically provisioned
in the MN. However, static provisioning of this information has its
drawbacks. It increases provisioning and network maintenance burden
for the operator. Moreover, static provisioning does not allow load
balancing, failover, opportunistic home link assignment etc. For
example, the user may be accessing the network from a location that
may be geographically far away from the preconfigured home link; the
administrative burden to configure the MN's with the respective
addresses is large and the ability to react on environmental changes
is minimal. In these situations static provisioning may not be
desirable.
Dynamic assignment of Mobile IPv6 home registration information is a
desirable feature for ease of deployment and network maintenance.
For this purpose, the RADIUS infrastructure, which is used for access
authentication, can be leveraged to assign some or all of the
necessary parameters. The RADIUS server in the Access Service
Provider (ASP) or in the Mobility Service Provider's (MSP) network
may return these parameters to the AAA client. The AAA client might
either be the NAS, in case of the integrated scenario, or the HA, in
case of the split scenario. The terms integrated and split are
described in the terminology section and were introduced in [6].
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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 [1].
General mobility terminology can be found in [7]. The following
additional terms, as defined in [6], are used in this document:
Access Service Authorizer (ASA):
A network operator that authenticates a MN and establishes the
MN's authorization to receive Internet service.
Access Service Provider (ASP):
A network operator that provides direct IP packet forwarding to
and from the MN.
Mobility Service Authorizer (MSA):
A service provider that authorizes Mobile IPv6 service.
Mobility Service Provider (MSP):
A service provider that provides Mobile IPv6 service. In order to
obtain such service, the MN must be authenticated and authorized
to obtain the Mobile IPv6 service.
Split Scenario:
A scenario where the mobility service and the network access
service are authorized by different entities.
Integrated Scenario:
A scenario where the mobility service and the network access
service are authorized by the same entity.
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3. Solution Overview
This document addresses the authentication, authorization and
accounting functionality required by for the MIPv6 bootstrapping as
outlined in the MIPv6 bootstrapping problem statement document (see
[6]). As such, the AAA functionality for the integrated and the
split scenario needs to be defined. This requires the ability to
offer support for the HA to AAA server and the network access server
to AAA server communication.
To highlight the main use cases, we briefly describe the integrated
and the split scenarios in Section 3.1 and Section 3.2, respectively.
3.1. Integrated Scenario
In the integrated scenario MIPv6 bootstrapping is provided as part of
the network access authentication procedure. Figure 1 shows the
participating entity.
+---------------------------+ +-----------------+
|Access Service Provider | |ASA/MSA/(/MSP) |
|(Mobility Service Provider)| | |
| | | +-------+ |
| +-------+ | | |Remote | |
| |Local | RADIUS | | |RADIUS | |
| |RADIUS |-------------------------|Server | |
| |Proxy | | | +-------+ |
| +-------+ | | ^ |
| ^ ^ | | |RADIUS |
| | | | | | |
| | | | | v |
| |RADIUS | | +-------+ |
| | | +-------+ | | |Local | |
| | | RADIUS |Home | | | |Home | |
| | +------->|Agent | | | |Agent | |
| | |in ASP | | | +-------+ |
| v +-------+ | +-----------------+
+-------+ IEEE | +-----------+ +-------+ |
|Mobile | 802.1X | |NAS / Relay| |DHCPv6 | |
|Node |----------+-|RADIUS |---|Server | |
| | PANA,... | |Client | | | |
+-------+ DHCP | +-----------+ +-------+ |
+---------------------------+
Figure 1: Mobile IPv6 Service Access in the Integrated Scenario
In the typical Mobile IPv6 access scenario as shown above, the MN
attaches in a ASP's network. During this network attachment
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procedure, the NAS/RADIUS client interacts with the MN. As shown in
Figure 1, the authentication and authorization happens via a RADIUS
infrastructure.
At the time of authorizing the user for IPv6 access, the RADIUS
server in the MSA detects that the user is authorized for Mobile IPv6
access. Based on the MSA's policy, the RADIUS server may allocate
several parameters to the MN for use during the subsequent Mobile
IPv6 protocol interaction with the HA.
Depending on the details of the solution interaction with the DHCPv6
server may be required, as described in [2].
3.2. Split Scenario
In the split scenario, Mobile IPv6 bootstrapping is not provided as
part of the network access authentication procedure. The Mobile IPv6
bootstrapping procedure is executed with the Mobility Service
Provider when desired by the MN. Two variations can be considered:
1. the MSA and the MSP are the same entity.
2. the MSA and the MSP are different entities.
Since scenario (1) is the more generic scenario we show it in
Figure 2.
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+----------------------+
| |
|Mobility +-------+ |
|Service |Remote | |
|Authorizer |RADIUS | |
|(MSA) |Server | |
| +-------+ |
+---------------^------+
|
|RADIUS
|
|
+---------------------------------|------+
|Mobility Service Provider (MSP) v |
+-------+ | +-----------+ +-------+ |
|Mobile | MIPv6 / | |HA/ | RADIUS |Local | |
|Node |-------------|RADIUS |-------------- |RADIUS | |
| | IKEv2 | |Client | |Proxy | |
+-------+ | +-----------+ +-------+ |
+----------------------------------------+
Figure 2: Mobile IPv6 service access in the split scenario (MSA !=
MSP)
As shown in Figure 2 the interaction between the RADIUS client and
the RADIUS server is triggered by the protocol interaction between
the MN and the HA/RADIUS client using IKEv2 (see [3] and [8]). The
HA / RADIUS Client interacts with the RADIUS infrastructure to
perform authentication, authorization, accounting and parameter
bootstrapping. The exchange is triggered by the home agent and an
interaction with the RADIUS infrastructure is initiated. When the
protocol exchange is completed then the HA needs to possess the
Mobile IPv6 specific parameters (see [6]).
Additionally, the MN might instruct the RADIUS server (via the home
agent) to perform a dynamic DNS update.
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4. RADIUS Attribute Overview
4.1. MIP6-HA Attribute
The RADIUS server may decide to assign a HA to the MN that is in
close proximity to the point of attachment (e.g., determined by the
NAS-ID). There may be other reasons for dynamically assigning HAs to
the MN, for example to share the traffic load. The attribute also
contains the prefix length so that the MN can easily infer the Home
Link prefix from the HA address.
4.2. MIP6-HA-FQDN Attribute
The RADIUS server may assign an FQDN of the HOA to the MN. The
mobile node can perform DNS query with the FQDN to derive the HA
address.
4.3. MIP6-HL-Prefix Attribute
For the same reason as the HA assignment, the RADIUS server may
assign a Home Link that is in close proximity to the point of
attachment (NAS-ID). The MN can perform [5] specific procedures to
discover other information for Mobile IPv6 registration.
4.4. MIP6-HOA Attribute
The RADIUS server may assign a HOA to the MN. This allows the
network operator to support mobile devices that are not configured
with static addresses. The attribute also contains the prefix length
so that the MN can easily infer the Home Link prefix from the HA
address.
4.5. MIP6-DNS-MO Attribute
By using this payload the RADIUS client instructs the RADIUS server
to perform a dynamic DNS update. When this payload is included in
the reverse direction, i.e., from the RADIUS server to the RADIUS
client, it informs about the status of the dynamic DNS update. When
the payload is sent from the RADIUS client to the RADIUS server then
the response MUST include the MIP6-DNS-MO attribute.
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5. RADIUS attributes
This section defines format and syntax for the attribute that carries
the Mobile IPv6 parameters that are described in the previous
section.
The attributes MAY be present in Access-Accept, Accounting-Request.
5.1. MIP6-HA Attribute
This attribute is sent by the RADIUS server to the NAS in an Access-
Accept packet. The attribute carries the assigned HA address.
This attribute MAY be sent by the NAS to the RADIUS server in an
Access-Request packet as a hint to suggest a dynamic HA that may be
assigned to the MN. The RADIUS server MAY use this value or may
ignore this suggestion.
If available at the NAS, at least MIP6-HA attribute and/or MIP6-HA-
FQDN SHOULD appear in accounting packets to indicate the identity of
the serving HA for this session.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Reserved | Prefix-Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| |
| IPv6 address of assigned HA |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type:
ASSIGNED-HA-ADDR-TYPE to be defined by IANA.
Length:
= 20 octets
Reserved:
Reserved for future use. The bits MUST be set to zero by the
sender, and MUST be ignored by the receiver.
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Prefix-Length:
This field indicates the prefix length of the Home Link.
IPv6 address of assigned HA:
128-bit IPv6 address of the assigned HA.
5.2. MIP6-HA-FQDN Attribute
This attribute is sent by the RADIUS server to the NAS in an Access-
Accept packet. The attribute carries the FQDN of the assigned HA.
This attribute MAY be sent by the NAS to the RADIUS server in an
Access-Request packet as a hint to suggest a dynamic HA that may be
assigned to the MN. The RADIUS server MAY use this value or may
ignore this suggestion.
If available at the NAS, at least MIP6-HA-FQDN attribute and/or
MIP6-HA SHOULD appear in accounting packets to indicate the identity
of the serving HA for this session.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | FQDN of the assigned HA .....
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type:
ASSIGNED-HA-FQDN-TYPE to be defined by IANA.
Length:
Variable length.
FQDN of the assigned HA:
The data field MUST contain a FQDN as described in [9].
5.3. MIP6-HL-Prefix Attribute
This attribute is sent by the RADIUS-MIP server to the NAS in an
Access-Accept packet. The attribute carries the assigned Home Link
prefix.
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This attribute MAY be sent by the NAS to the RADIUS server in an
Access-Request packet along with the MIP6-HA and/or MIP6-HA-FQDN
attribute as a hint to suggest a Home Link prefix that may be
assigned to the MN. The RADIUS server MUST use this value if it
accepts the NAS's HA suggestion.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Reserved | Prefix-Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| |
| Home Link Prefix |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type:
ASSIGNED-HL-TYPE to be defined by IANA.
Length:
>= 4 octets + the minimum length of a prefix.
Reserved:
Reserved for future use. The bits MUST be set to zero by the
sender, and MUST be ignored by the receiver.
Prefix-Length:
This field indicates the prefix length of the Home Link.
Home Link Prefix:
Home Link prefix (upper order bits) of the assigned Home Link
where the MN should send binding update.
5.4. MIP6-HOA Attribute
This attribute is sent by the RADIUS server to the NAS in an Access-
Accept packet. The attribute carries the assigned Home IPv6 Address
for the MN.
This attribute MAY be sent by the NAS to the RADIUS server in an
Access-Request packet along with the MIP6-HA and/or MIP6-HA-FQDN
attribute as a hint to suggest a Home Address that may be assigned to
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the MN. The RADIUS server MUST use this value if it accepts the
NAS's HA suggestion.
If available at the NAS, this attribute SHOULD appear in the
accounting packets so that the IPv6 addressed used for this session
is known in the accounting stream.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Reserved | Prefix-Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| |
| Assigned IPv6 HOA |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type:
ASSIGNED-HOA-TYPE to be defined by IANA.
Length:
= 20 octets.
Reserved:
Reserved for future use. The bits MUST be set to zero by the
sender, and MUST be ignored by the receiver.
Prefix-Length:
This field indicates the prefix length of the Home Link.
Assigned IPv6 HOA:
IPv6 HOA that is assigned to the MN.
5.5. MIP6-DNS-MO Attribute
The MIP6-DNS-MO attribute is used for triggering a DNS update by the
RADIUS server and to return the result to the RADIUS client. The
request MUST carry the MN's FQDN but the attribute carried in
response to the request MAY not carry a FQDN value.
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Reserved-1 | Status |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|R| Reserved-2 | FQDN ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type:
DNS-UPDATE-TYPE to be defined by IANA.
Length:
Variable length.
Reserved-1:
Reserved for future use. The bits MUST be set to zero by the
sender, and MUST be ignored by the receiver.
Status:
This 8 bit unsigned integer field indicates the result of the
dynamic DNS update procedure as defined in [3]. This field
MUST be set to 0 and ignored by the RADIUS server when the
MIP6-DNS-MO is sent from the RADIUS client to the RADIUS
server. When the MIP6-DNS-MO is provided in the response,
values of the Status field less than 128 indicate that the
dynamic DNS update was performed successfully by the RADIUS
server. Values greater than or equal to 128 indicate that the
dynamic DNS update was not successfully completed. The
following values for the Status field are currently defined:
0 DNS update performed
128 Reason unspecified
129 Administratively prohibited
130 DNS Update Failed
R flag:
If this bit for the R flag is set then the RADIUS client
requests the RADIUS server to remove the DNS entry identified
by the FQDN included in this attribute. If not set, the RADIUS
client is requesting the RADIUS server to create or update a
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DNS entry with the FQDN specified in this attribute and the
Home Address carried in another attribute specified in this
document.
Reserved-2:
Reserved for future use. The bits MUST be set to zero by the
sender, and MUST be ignored by the receiver.
FQDN of the MN:
In an Access-Request packet the data field MUST contain a FQDN.
In an Access-Accept packet the data field MAY contain an FQDN.
FQDN is described in [9].
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6. Message Flows
6.1. Integrated Scenario (MSA=ASA)
This section is based on [2] and uses the previously defined RADIUS
attributes.
6.1.1. HA allocation in the MSP
RADIUS is used to authenticate the MN, to authorize it for the
mobility service and to send information about the assigned HA to the
NAS.
|
--------------ASP------>|<--ASA+MSA--
|
+----+ +------+ +-------+ +-------+
| | |RADIUS| | | | |
| | |Client| | | | |
| MN | |NAS/ | | DHCP | |Home |
| | |DHCP | | Server| |RADIUS |
| | |Relay | | | |Server |
+----+ +------+ +-------+ +-------+
| | | |
| 1 | 1 | |
|<------------->|<---------------------->|
| | | |
| | | |
| 2 | | |
|-------------->| | |
| | | |
| | 3 | |
| |------------>| |
| | | |
| | 4 | |
| |<------------| |
| | | |
| 5 | | |
|<--------------| | |
| | | |
HA allocation in the MSP
In step (1), the MN executes the normal network access authentication
procedure (e.g., IEEE 802.11i/802.1x, PANA) with the NAS. The NAS
acts as an authenticator in "pass-through" mode, i.e., the endpoint
of the authentication dialogue is the MN's home RADIUS server. This
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is the typical scenario in case the messages involved in the
authentication protocol are transported in EAP.
As per [10], the NAS encapsulates/decapsulates EAP packets into/from
RADIUS packets until an Access-Response (either an Access-Accept or
an Access/Reject packet is received by the NAS). This concludes the
network access authentication phase.
Depending on the RADIUS server configuration, the MIP6-HA attribute
or the the MIP6-HA-FQDN attribute may be appended to the Access-
Accept packet. In the latter case the MN needs to perform a DNS
query in order to discover the HA address.
The MIP6-HA or MIP6-HA-FQDN attribute is appended to the Access-
Accept in case the home RADIUS server knows or has allocated a HA to
the Access-Request (this is assumed in this scenario).
In step (2) the MN sends a DHCPv6 Information Request message to
all_DHCP_Relay_Agents_and_Servers. In the OPTION_ORO, Option Code
for the Home Network Identifier Option shall be included in that
message. The Home Network Identifier Option should have id-type of
1, the message is a request to discover home network information that
pertains to the given realm, i.e., the user's home domain (identified
by the NAI of the MN). The OPTION_CLIENTID is set by the MN to
identify itself to the DHCP server.
In step (3) the DHCP relay agent forwards this request to the DHCP
server. The OPTION_MIP6-RELAY-Option is included in this forwarded
message. This option carries the RADIUS MIP6-HA Attribute from the
Access-Accept packet.
In step (4), the DHCP server identifies the client (by DUID) and
finds out that it requests HA information in the MSP (by the Home
Network Identifier Option = 1). The DHCP server extracts the HA
address from OPTION_MIP6-RELAY-Option and places it into Home Network
Information Option in the Reply message.
In step (5), the Relay Agent forwards the Reply Message to the MN.
On reception of this message, the HA address or the FQDN of the home
agent is available at the MN.
6.1.2. HA allocation in the ASP (visited network)
This scenario is similar to the one described in Section 6.1.1. The
difference is in step (2), where the type-id field in the Home
Network Identifier Option is set to zero, indicating that a HA is
requested in the ASP instead of in the MSP. Thus, the information
received by the home RADIUS server, via the DHCP relay, in the
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OPTION_MIP6-RELAY-Option (Information Request) is ignored. The DHCP
server allocates a HA from its list of possible HAs and returns it in
the Reply message (Home Network Information Option).
6.2. Split Scenario (MSA!=ASA)
6.2.1. Mobile Service Provider and Mobile Service Authorizer are the
same entity.
The assumption in this scenario is that the MN has the domain name of
the MSP preconfigured.
In this scenario there is no relationship between the network access
authentication procedure and the MIPv6 bootstrapping procedure.
In order to learn the IP address of the HA, the MN either performs a
DNS lookup of the HA Name or a DNS lookup by service name. In the
first case, the MN is preconfigured with the FQDN of the HA, and thus
sends a DNS request, where QNAME = name of HA, QTYPE='AAAA' (request
for IPv6 address of HA). A DNS reply message is returned by the DNS
server with the HA address.
The MN then runs IKEv2 [11] with the HA in order to set up IPsec SAs
(MN-HA). As part of this,the MN authenticates itself to the RADIUS
server in the MSA domain, and obtains authorization for mobility
service (including the Home Address).
The MN shares credentials with the RADIUS server in the MSA domain.
The RADIUS communication between the HA and the this RADIUS server is
also secured by RADIUS-specific mechanisms (e.g., IPsec). Using EAP
within IKEv2 [11], the MN is authenticated and authorized for the
IPv6 mobility service and is also assigned a HOA.
The setup of SAs and mutual authentication between MN and AAAH using
RADIUS (and EAP) is similar to the one described for Diameter
protocol in [12]. The described mechanism ensureas that common
keying material will be available at the MN and HA after successful
completion.
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----------------------------ASP--------->|<-----MSA/MSP
+----+ IKEv2 +----+ RADIUS (EAP) +--------------------+
| MN |<----------->| HA |<-------------------->|Remote RADIUS Server|
+----+ +----+ +--------------------+
MN HA Remote RADIUS server
-- -- --------------------
IKE_SA_INIT
<------------------------------>
HDR, SK{IDi,[CERTREQ,] [IDr,]
SAi2, TSi, TSr}
------------------------------->
RADIUS Access-Request(EAP-Response)
---------------------------------->
RADIUS Access-Challenge(EAP-Request)
<-----------------------------------
HDR, SK {IDr, [CERT,] AUTH,
EAP }
<-------------------------------
HDR, SK {EAP}
-------------------------------->
RADIUS Access-Request(EAP-Response)
---------------------------------->
RADIUS Access-Challenge(EAP-Request)
<-----------------------------------
HDR, SK{EAP-Request}
<-------------------------------
HDR, SK{EAP-Response}
-------------------------------->
RADIUS Access-Request(EAP-Response)
---------------------------------->
... ...
RADIUS Access-Accept(EAP-Success)
<------------------------
HDR, SK{EAP-Success}
<-------------------------------
HDR, SK{AUTH}
------------------------------->
HDR, SK {AUTH, SAr2, TSi, TSr }
<-------------------------------
Split Scenario Exchange
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MN and HA start with an IKE_SA_INIT to setup the IKE SA (messages
defined in the IKEv2 specification [11], negotiating crypto
algorithms and running DH key exchange). IKEv2 supports integration
with EAP. The MN indicates its desire to use EAP by not including
the AUTH payload in the third message. However, it indicates its
identity (NAI) by using the IDi field. If the HA supports EAP for
authentication, as per [10] it forwards the identity to the Remote
RADIUS server by sending a RADIUS Access-Request packet containing
the identity in the EAP-Payload AVP and in the RADIUS User-Name
attribute. Based on this identity, the Remote RADIUS server chooses
authentication method and sends the first EAP-Request in the RADIUS
Access-Challenge packet. During the EAP authentication phase, the HA
relays EAP packets between the MN and the Remote RADIUS server. If
the authentication succeeds and if the MN is authorized to use Mobile
IPv6 service, the Remote RADIUS server sends a RADIUS Access-Accept
packet containing the EAP-Success and the AAA-Key derived from the
EAP authentication method. EAP authentication methods that do not
derive keys are not recommended. This key is used by both MN and HA
to generate the AUTH payload. In subsequent messages, MN and HA
setup IPsec SAs for Mobile IPv6.
6.2.2. Mobile Service Provider and Mobile Service Authorizer are
different entities.
The HA address discovery is performed as described in Section 6.2.1.
-----------ASP--------->|<-----MSP------------------->|<-----MSA--------
+----+ IKEv2 +----+ RADIUS (EAP)+------+ RADIUS(EAP)+------+
| MN |<----------> | HA |<----------->|Local |<---------->|Remote|
+----+ +----+ |RADIUS| |RADIUS|
|Proxy | |Server|
+------+ +------+
MSP#MSA Exchange
The scenario is similar to previously described scenarios with the
difference of utilizing AAA roaming agreements between the MSP and
the MSA.
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7. Goals for the HA-AAA Interface
Here, we follow the classification and labels listed in the MIPv6-
AAA-Goals document [13].
7.1. General Goals
G1.1-G1.4 Security
These are standard requirements for a AAA protocol - mutual
authentication, integrity, replay protection, confidentiality. IPsec
can be used to achieve the goals. Goal G1.5 regarding inactive peer
detection needs further investigations since heartbeat messages do
not exist (like in the Diameter case, Watch-Dog-Request/Answer).
7.2. Service Authorization
G2.1. The AAA-HA interface should allow the use of Network Access
Identifier (NAI) to identify the MN. The User-Name attribute can be
used for the purpose to carry the NAI.
G2.2 The HA should be able to query the AAAH server to verify Mobile
IPv6 service authorization for the MN. Any node implementing RADIUS
functionality[4] can possibly initiate a request message. In
combination with the ability of the RADIUS protocol to carry EAP
messages [10] , our solution will enable an HA to query a RADIUS
server and verify MIPv6 authorization for the MN.
G2.3 The AAAH server should be able to enforce explicit operational
limitations and authorization restrictions on the HA (e.g., packet
filters, QoS parameters). Work in progress in the area, including
NAS-Filter-Rule, RADIUS quality of service support, prepaid
extensions etc. is performed. The relevant attributes may be reused
for providing required functionality over the AAAH-HA interface.
G2.4 - G2.6. Issues addressing the maintenance of a Mobile IPv6
session by the AAAH server, e.g., authorization lifetime, extension
of the authorization lifetime and explicit session termination by the
AAAH server side.
The attribute Session-Timeout may be sent in Access-Challenge or
Access-Accept packet by the RADIUS server, thus limiting the
authorization session duration. In order to reauthenticate/
reauthorize the user, the Termination-Action attribute can be
included, with value 1, meaning the NAS should send a new RADIUS-
Request packet. Additional AVPs for dealing with pre-paid sessions
(e.g,. volume, resource used--VolumeQuota AVP, ResourceQuota AVP) are
specified in RADIUS prepaid extension. Exchanging of application
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specific authorization request/answer messages provides extension of
the authorization session (e.g., Authorize Only Access-Request sent
by the HA (NAS) to the RADIUS server). Initiation of the re-
authorization by both sides could be supported. Both sides could
initiate session termination - the RADIUS server by sending
Disconnect message [14].
7.3. Accounting
G3.1 The AAA-HA interface must support the transfer of accounting
records needed for service control and charging. These include (but
may not be limited to): time of binding cache entry creation and
deletion, octets sent and received by the MN in bi-directional
tunneling, etc.
The requirements for accounting over the AAAH-HA interface does not
require enhancements to the existing accounting functionality.
7.4. MN Authentication
G4.1 The AAA-HA interface MUST support pass-through EAP
authentication with the HA working as EAP authenticator operating in
pass-through mode and the AAAH server working as back-end
authentication server.
These issues require the functionality of AAAH server working as a
back-end authentication server and HA working as NAS and EAP
authenticator in pass-through mode for providing a MN authentication.
This document suggests this mode of operation in the context of the
relevant scenarios.
7.5. Provisioning of Configuration Parameters
G5.1 The HA should be able to communicate to the AAAH server the HOA
allocated to the MN (e.g. for allowing the AAAH server to perform DNS
update on behalf of the MN).
This document describes needed AVPs for this purpose, see section
"DNS Update Mobility Option Attribute"
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8. Table of Attributes
The following tables provides a guide to which attributes may be
found in RADIUS packet and in what number.
The following defines the meaning of the notation used in the following
tables:
0 This attribute MUST NOT be present.
0-1 Zero or one instance of this attribute MAY be present.
Request Accept Reject Challenge Type Attribute
0-1[a] 0-1[a] 0 0 MIP6-HA-TYPE MIP6-HA Attribute
0-1[a] 0-1[a] 0 0 MIP6-HA-FQDN-TYPE MIP6-HA-FQDN Attribute
0-1[b] 0-1 0 0 MIP6-HL-PREFIX-TYPE MIP6-HL-Prefix Attribute
0-1[b] 0-1 0 0 MIP6-HOA-TYPE MIP6-HOA Attribute
0-1 0-1 0 0 MIP6-DNS-MO-TYPE MIP6-DNS-MO Attribute
Notes:
[a] Either MIP6-HA or MIP6-HA-FQDN MAY appear in a RADIUS packet.
[b] If MIP6-HA or MIP6-HA-FQDN are present in the Access-Request
then these attributes MUST also be present in the Access-Request.
If the RADIUS server accepts the NAS suggestion for the HA, then
the RADIUS server MUST also include the values received for these
attributes in the Access-Accept.
As used in accounting packets:
Request Interim Stop Type Attribute
0-1 0-1 0-1 MIP6-HA-TYPE MIP6-HA Attribute
0-1 0-1 0-1 MIP6-HA-FQDN-TYPE MIP6-HA-FQDN Attribute
0 0 0 MIP6-HL-PREFIX-TYPE MIP6-HL-Prefix Attribute
0-1 0-1 0-1 MIP6-HOA-TYPE MIP6-HOA Attribute
0 0 0 MIP6-DNS-MO-TYPE MIP6-DNS-MO Attribute
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9. Diameter Considerations
When used in Diameter, the attributes defined in this specification
can be used as Diameter AVPs from the Code space 1-255 (RADIUS
attribute compatibility space). No additional Diameter Code values
are therefore allocated. The data types and flag rules for the
attributes are as follows:
+---------------------+
| AVP Flag rules |
|----+-----+----+-----|----+
| | |SHLD| MUST| |
Attribute Name Value Type |MUST| MAY | NOT| NOT|Encr|
-------------------------------|----+-----+----+-----|----|
MIP6-HA Address | M | P | | V | Y |
MIP6-HA-FQDN UTF8String | M | P | | V | Y |
MIP6-HL-Prefix OctetString| M | P | | V | Y |
MIP6-HOA Address | M | P | | V | Y |
MIP6-DNS-MO OctetString| M | P | | V | Y |
-------------------------------|----+-----+----+-----|----|
Other than MIP6-HA and HOA-IPv6, the attributes in this specification
have no special translation requirements for Diameter to RADIUS or
RADIUS to Diameter gateways; they are copied as is, except for
changes relating to headers, alignment, and padding. See also [15]
Section 4.1 and [16] Section 9. MIP6-HA and HOA-IPv6 must be
translated between their RADIUS representation of String to a
Diameter Address format which requires that the AddressType field be
set to 2 for IP6 (IP version 6)
What this specification says about the applicability of the
attributes for RADIUS Access-Request packets applies in Diameter to
AA-Request [16] or Diameter-EAP-Request [17]. What is said about
Access-Challenge applies in Diameter to AA-Answer [16] or Diameter-
EAP-Answer [17] with Result-Code AVP set to
DIAMETER_MULTI_ROUND_AUTH.
What is said about Access-Accept applies in Diameter to AA-Answer or
Diameter-EAP-Answer messages that indicate success. Similarly, what
is said about RADIUS Access-Reject packets applies in Diameter to AA-
Answer or Diameter-EAP-Answer messages that indicate failure.
What is said about Accounting-Request applies to Diameter Accounting-
Request [16] as well.
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10. Security Considerations
Assignment of these values to a user should be based on successful
authentication of the user at the NAS and/or at the HA. The RADIUS
server should only assign these values to a user who is authorized
for Mobile IPv6 service (this check could be performed with the
user's subscription profile in the Home Network).
The NAS and the HA to the RADIUS server transactions must be
adequately secured. Otherwise there is a possibility that the user
may receive fraudulent values from a rogue RADIUS server potentially
hijacking the user's Mobile IPv6 session.
These new attributes do not introduce additional security
considerations besides the ones identified in [4].
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11. IANA Considerations
The following RADIUS attribute Type values MUST be assigned by IANA.
MIP6-HA-TYPE
MIP6-HA-FQDN-TYPE
MIP6-HL-PREFIX-TYPE
MIP6-HOA-TYPE
MIP6-DNS-MO-TYPE
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12. Acknowledgements
We would like to thank the following individuals for their review and
constructive comments during the development of this document:
Florian Kohlmayer, Mark Watson, Jayshree Bharatia, Dimiter Milushev,
Andreas Pashalidis, Rafa Marin Lopez and Pasi Eronen.
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13. References
13.1. Normative References
[1] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.
[2] Chowdhury, K. and A. Yegin, "MIP6-bootstrapping via DHCPv6 for
the Integrated Scenario",
draft-ietf-mip6-bootstrapping-integrated-dhc-01 (work in
progress), June 2006.
[3] Giaretta, G., "Mobile IPv6 bootstrapping in split scenario",
draft-ietf-mip6-bootstrapping-split-03 (work in progress),
October 2006.
[4] Rigney, C., Willens, S., Rubens, A., and W. Simpson, "Remote
Authentication Dial In User Service (RADIUS)", RFC 2865,
June 2000.
13.2. Informative References
[5] Johnson, D., Perkins, C., and J. Arkko, "Mobility Support in
IPv6", RFC 3775, June 2004.
[6] Giaretta, G. and A. Patel, "Problem Statement for bootstrapping
Mobile IPv6", draft-ietf-mip6-bootstrap-ps-05 (work in
progress), May 2006.
[7] Manner, J. and M. Kojo, "Mobility Related Terminology",
RFC 3753, June 2004.
[8] Dupont, F. and V. Devarapalli, "Mobile IPv6 Operation with
IKEv2 and the revised IPsec Architecture",
draft-ietf-mip6-ikev2-ipsec-06 (work in progress), April 2006.
[9] Mockapetris, P., "Domain names - implementation and
specification", STD 13, RFC 1035, November 1987.
[10] Aboba, B. and P. Calhoun, "RADIUS (Remote Authentication Dial
In User Service) Support For Extensible Authentication Protocol
(EAP)", RFC 3579, September 2003.
[11] Kaufman, C., "Internet Key Exchange (IKEv2) Protocol",
RFC 4306, December 2005.
[12] Tschofenig, H., "Mobile IPv6 Bootstrapping using Diameter",
draft-tschofenig-mip6-aaa-ha-diameter-01 (work in progress),
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October 2005.
[13] Giaretta, G., "AAA Goals for Mobile IPv6",
draft-ietf-mip6-aaa-ha-goals-03 (work in progress),
September 2006.
[14] Chiba, M., Dommety, G., Eklund, M., Mitton, D., and B. Aboba,
"Dynamic Authorization Extensions to Remote Authentication Dial
In User Service (RADIUS)", RFC 3576, July 2003.
[15] Calhoun, P., Loughney, J., Guttman, E., Zorn, G., and J. Arkko,
"Diameter Base Protocol", RFC 3588, September 2003.
[16] Calhoun, P., Zorn, G., Spence, D., and D. Mitton, "Diameter
Network Access Server Application", RFC 4005, August 2005.
[17] Eronen, P., Hiller, T., and G. Zorn, "Diameter Extensible
Authentication Protocol (EAP) Application", RFC 4072,
August 2005.
[18] Arends, R., Austein, R., Larson, M., Massey, D., and S. Rose,
"DNS Security Introduction and Requirements", RFC 4033,
March 2005.
[19] Arkko, J., Devarapalli, V., and F. Dupont, "Using IPsec to
Protect Mobile IPv6 Signaling Between Mobile Nodes and Home
Agents", RFC 3776, June 2004.
[20] Vixie, P., Thomson, S., Rekhter, Y., and J. Bound, "Dynamic
Updates in the Domain Name System (DNS UPDATE)", RFC 2136,
April 1997.
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Authors' Addresses
Kuntal Chowdhury
Starent Networks
30 International Place
Tewksbury, MA 01876
US
Phone: +1 214-550-1416
Email: kchowdhury@starentnetworks.com
Avi Lior
Bridgewater Systems
303 Terry Fox Drive, Suite 100
Ottawa, Ontario
Canada K2K 3J1
Phone: +1 613-591-6655
Email: avi@bridgewatersystems.com
Hannes Tschofenig
Siemens
Otto-Hahn-Ring 6
Munich, Bavaria 81739
Germany
Email: Hannes.Tschofenig@siemens.com
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Full Copyright Statement
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