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RADIUS Attribute for 4rd
draft-jiang-softwire-4rd-radius-02

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This is an older version of an Internet-Draft whose latest revision state is "Expired".
Authors Sheng Jiang , Yu Fu , Bing Liu
Last updated 2013-02-20
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draft-jiang-softwire-4rd-radius-02
Network Working Group                             Sheng Jiang (Editor)
Internet Draft                                                   Yu Fu
Intended status: Standards Track                              Bing Liu
Expires: August 24, 2013                  Huawei Technologies Co., Ltd
                                                     February 21, 2013

                        RADIUS Attribute for 4rd

                 draft-jiang-softwire-4rd-radius-02.txt

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   This Internet-Draft will expire on August 24, 2013.

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Abstract

   IPv4 Residual Deployment via IPv6 (4rd) is a stateless mechanism for
   running IPv4 over IPv6-only infrastructure. It provides both IPv4 and
   IPv6 connectivity services simultaneously during the IPv4/IPv6 co-
   existing period. The Dynamic Host Configuration Protocol for IPv6
   (DHCPv6) 4rd options has been defined to configure 4rd Customer Edge
   (CE). However, in many networks, the configuration information may be
   stored in Authentication Authorization and Accounting (AAA) servers
   while user configuration is mainly from Broadband Network Gateway
   (BNG) through DHCPv6 protocol. This document defines a Remote
   Authentication Dial In User Service (RADIUS) attribute that carries
   4rd configuration information from AAA server to BNG. The 4rd RADIUS
   attribute are designed following the simplify principle. It provides
   just enough information to form the correspondent DHCPv6 4rd option.

Table of Contents

   1. Introduction ................................................. 3
   2. Terminology .................................................. 3
   3. 4rd Configuration process with RADIUS ........................ 3
   4. Attributes ................................................... 6
      4.1. 4rd-Configuration Attribute ............................. 6
      4.2. 4rd Non-mapping-rule Parameter option ................... 7
      4.3. 4rd Rule Options ........................................ 7
      4.4. 4rd Rule Sub Options .................................... 8
         4.4.1. Rule-IPv6-Prefix Sub Option ........................ 8
          Rule-IPv6-Suffix Sub Option .............................. 9
         4.4.3. Rule-IPv4-Prefix Sub Option ....................... 10
         4.4.4. Misc Sub Option ................................... 11
      4.5. Table of attributes .................................... 11
   5. Diameter Considerations ..................................... 12
   6. Security Considerations ..................................... 12
   7. IANA Considerations ......................................... 12
   8. Acknowledgments ............................................. 13
   9. References .................................................. 13
      9.1. Normative References ................................... 13
      9.2. Informative References ................................. 13

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1. Introduction

   Recently providers start to deploy IPv6 and consider how to transit
   to IPv6. IPv4 Residual Deployment via IPv6 (4rd)
   [I-D.ietf-softwire-4rd] is a stateless mechanism for running IPv4
   over IPv6-only infrastructure. It provides both IPv4 and IPv6
   connectivity services simultaneously during the IPv4/IPv6 co-existing
   period. 4rd has adopted Dynamic Host Configuration Protocol for IPv6
   (DHCPv6) [RFC3315] as auto-configuring protocol. The 4rd Customer
   Edge (CE) uses the DHCPv6 extension options
   [I-D.ietf-softwire-4rd] to discover 4rd Border Relay and to configure
   relevant 4rd rules.

   In many networks, user configuration information may be managed by
   AAA (Authentication, Authorization, and Accounting) servers. Current
   AAA servers communicate using the Remote Authentication Dial In User
   Service (RADIUS) [RFC2865] protocol. In a fixed line broadband
   network, the Broadband Network Gateways (BNGs) act as the access
   gateway of users. The BNGs are assumed to embed a DHCPv6 server
   function that allows them to locally handle any DHCPv6 requests
   issued by hosts.

   Since the 4rd configuration information is stored in AAA servers and
   user configuration is mainly through DHCPv6 protocol between BNGs and
   hosts/CEs, new RADIUS attributes are needed to propagate the
   information from AAA servers to BNGs. The 4rd RADIUS attribute are
   designed following the simplify principle, while providing enough
   information to form the correspondent DHCPv6 4rd option.
   [I-D.ietf-softwire-4rd].

2. Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC2119 [RFC2119].

   The terms 4rd CE and 4rd Border Relay are defined in
   [I-D.ietf-softwire-4rd].

3. 4rd Configuration process with RADIUS

   The below Figure 1 illustrates how the RADIUS protocol and DHCPv6
   cooperate to provide 4rd CE with 4rd configuration information.

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     4rd CE                       BNG                       AAA Server
        |                          |                             |
        |------DHCPv6 Solicit----->|                             |
        |(Option Request w/ 4rd option)                          |
        |                          |--Access-Request(4rd Attr)-->|
        |                          |                             |
        |                          |<--Access-Accept(4rd Attr)---|
        |<---DHCPv6 Advertisement--|                             |
        |                          |                             |
        |------DHCPv6  Request---->|                             |
        |      (4rd Option)        |                             |
        |<---- -DHCPv6 Reply-------|                             |
        |      (4rd option)        |                             |
        |                          |                             |
                  DHCPv6                        RADIUS
             Figure 1: the cooperation between DHCPv6 and RADIUS
                       combining with RADIUS authentication

   BNGs act as a client of RADIUS and as a DHCPv6 server.  First, the
   4rd CE MAY initiate a DHCPv6 Solicit message that includes an Option
   Request option (6) [RFC3315] with the 4rd option
   [draft-ietf-softwire-4rd] from the 4rd CE.  When BNG receives the
   SOLICIT, it SHOULD initiate an RADIUS Access-Request message, in
   which the User-Name attribute (1) SHOULD be filled by the 4rd CE MAC
   address, to the RADIUS server and the User-password attribute (2)
   SHOULD be filled by the shared 4rd password that has been
   preconfigured on the DHCPv6 server, requesting authentication as
   defined in [RFC2865] with 4rd-Configuration attribute, defined in the
   next Section. If the authentication request is approved by the AAA
   server, an Access-Accept message MUST contain the 4rd-Configuration
   Attribute. After receiving the Access-Accept message with 4rd-
   Configuration Attribute, the BNG SHOULD respond to the user with an
   Advertisement message. Then the user can request a 4rd Option, the
   BNG SHOULD reply the user with a message containing the 4rd option.
   The recommended format of the MAC address is as defined in Calling-
   Station-Id (Section 3.20 in [RFC3580]) without the SSID (Service Set
   Identifier) portion.

   Figure 2 describes another scenario, in which the authorization
   operation is not coupled with authentication. Authorization relevant
   to 4RD is done independently after the authentication process.

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      4rd CE                       BNG                       AAA Server
         |                          |                             |
         |------DHCPv6  Request---->|                             |
         |(Option Request w/ 4rd option)                          |
         |                          |--Access-Request(4rd Attr)-->|
         |                          |                             |
         |                          |<--Access-Accept(4rd Attr)---|
         |                          |                             |
         |<------DHCPv6 Reply-------|                             |
         |      (4rd option)        |                             |
         |                          |                             |
                  DHCPv6                         RADIUS
               Figure 2: the cooperation between DHCPv6 and RADIUS
                         decoupled with RADIUS authentication

   In the abovementioned scenario, the Access-Request packet SHOULD
   contain a Service-Type attribute (6) with the value Authorize Only
   (17); thus, according to [RFC5080], the Access-Request packet MUST
   contain a State attribute that obtained from the previous
   authentication process.

   In both above-mentioned scenarios, Message-authenticator (type 80)
   [RFC2869] SHOULD be used to protect both Access-Request and Access-
   Accept messages.

   After receiving the 4rd-Configuration Attribute in the initial
   Access-Accept, the BNG SHOULD store the received 4rd configuration
   parameters locally. When the 4rd CE sends a DHCPv6 Request message to
   request an extension of the lifetimes for the assigned address, the
   BNG does not have to initiate a new Access-Request towards the AAA
   server to request the 4rd configuration parameters. The BNG could
   retrieves the previously stored 4rd configuration parameters and use
   them in its reply.

   If the BNG does not receive the 4rd-Configuration Attribute in the
   Access-Accept it MAY fallback to a pre-configured default 4rd
   configuration, if any. If the BNG does not have any pre-configured
   default 4rd configuration or if the BNG receives an Access-Reject,
   the tunnel cannot be established.

   As specified in [RFC3315], section 18.1.4, "Creation and Transmission
   of Rebind Messages ", if the DHCPv6 server to which the DHCPv6 Renew
   message was sent at time T1 has not responded by time T2, the 4rd CE
   (DHCPv6 client) enters the Rebind state and attempts to contact any
   available server. In this situation the secondary BNG receiving the
   DHCPv6 message MUST initiate a new Access-Request towards the AAA

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   server. The secondary BNG MAY include the 4rd-Configuration Attribute
   in its Access-Request.

4. Attributes

   This section defines 4rd-Configuration Attribute which is used in the
   4rd scenario. The attribute design follows [RFC6158].

   The 4rd RADIUS attribute are designed following the simplify
   principle. The sub options are organized into two categories: the
   necessary and the optional.

4.1. 4rd-Configuration Attribute

   The 4rd-Configuration Attribute is structured as follows:

    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     |                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               +
   |                                                               |
   +                          4rd Option(s)                        +
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

       Type

         TBD

       Length

         6 + the length of the Rule option(s)

       Sub Option

         a variable field that may contains a 4rd non-mapping-rule
         parameter option andone or more Rule option(s), defined in
         Section 4.2 and 4.3.

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4.2. 4rd Non-mapping-rule Parameter option

      0                   1                   2                   3
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |   option-code = OPTION_4RD    |         option-length         |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |H|      0    |T| traffic-class |         domain-pmtu           |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

       Type

         1

       Length

         4

       H bit

         Hub&spoke topology (= 1 if Yes)

       T bit

         Traffic-class flag (= 1 if a Tunnel traffic class is provided)

       traffic-class

         Tunnel-traffic class

       domain-pmtu

         Domain PMTU (at least 1280)

4.3. 4rd Rule Options

   Depending on deployment scenario, at least one BR Mapping Rule one
   and one or more CE Mapping Rules MUST be included in one 4rd-
   Configuration Attribute.

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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     |                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               +
   |                                                               |
   +                         Sub Options                           +
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

       Type

         2  BR Mapping Rule

         3  CE Mapping Rule

       Length

         2 + the length of the sub options

       Sub Option

         a variable field that contains necessary sub options defined in
         Section 4.3 and zero or several optional sub options, defined
         in Section 4.4.

4.4. 4rd Rule Sub Options

   Rule-IPv6-Prefix Sub Option and Rule-IPv4-Prefix Sub Option are
   necessary for every 4rd Rule option. They should appear for once and
   only once. Different from [I-D.ietf-softwire-4rd], EA-Len, Embedded-
   Address (EA) length, is not present at all, because it can be
   calculated by the combine of prefix4len, prefix6-len, excluded ports
   and off bits.

4.4.1. Rule-IPv6-Prefix Sub Option

   The IPv6 Prefix sub option is follow the framed IPv6 prefix designed
   in [RFC3162].

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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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    SubType    |    SubLen     |   Reserved    |  prefix6-len  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   |                        rule-ipv6-prefix                       |
   |                                                               |
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      SubType

         0 (SubType number, for the Rule-IPv6-Prefix6 sub option)

      SubLen

         20 (the length of the Rule-IPv6-Prefix6 sub option)

      Reserved

         Reserved for future usage. It should be set to all zero.

      prefix6-len

         length of the IPv6 prefix, specified in the rule-ipv6-prefix
         field, expressed in bits

      rule-ipv6-prefix

         a 128-bits field that specifies an IPv6 prefix that appears in
         a 4rd rule

4.4.2. Rule-IPv6-Suffix Sub Option

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    SubType    |    SubLen     |  suffix6-len  |  ipv6-suffix  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      SubType

         1 (SubType number, for the Rule-IPv6-Suffix6 sub option)

      SubLen

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         4 (the length of the Rule-IPv6-Suffix6 sub option)

      prefix6-len

         length of the IPv6 suffix, specified in the rule-ipv6-suffix
         field, expressed in bits. In attendance, the value should be
         1~4 only.

      rule-ipv6-suffix

         a 8-bits field that specifies an IPv6 suffix that appears in
         a 4rd rule

4.4.3. Rule-IPv4-Prefix Sub Option

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    SubType    |    SubLen     |   Reserved    |  prefix4-len  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                       rule-ipv4-prefix                        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      SubType

         2 (SubType number, for the Rule-IPv4-Prefix6 sub option)

      SubLen

         8 (the length of the Rule-IPv4-Prefix6 sub option)

      Reserved

         Reserved for future usage. It should be set to all zero.

      Prefix4-len

         length of the IPv6 prefix, specified in the rule-ipv6-prefix
         field, expressed in bits

      rule-ipv4-prefix

         a 32-bits field that specifies an IPv4 prefix that appears in
         a 4rd rule

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4.4.4. Misc Sub Option

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    SubType    |    SubLen     |   Reserved  |W|
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      SubType

         3 (SubType number, for the Rule-IPv4-Prefix6 sub option)

      SubLen

         1 (the length of the Rule-IPv4-Prefix6 sub option)

      Reserved

         Reserved for future usage. It should be set to all zero.

       W bit

         WKP authorized, = 1 if set

4.5. Table of attributes

   The following table provides a guide to which attributes may be found
   in which kinds of packets, and in what quantity.

   Request Accept Reject Challenge Accounting  #  Attribute
                                    Request
    0-1     0-1     0      0         0-1      TBD1  4rd-
                                                   Configuration
    0-1     0-1     0      0         0-1      1    User-Name
    0-1     0       0      0         0-1      2    User-Password
    0-1     0-1     0      0         0-1      6    Service-Type
    0-1     0-1     0-1    0-1       0-1      80   Message-Authenticator

   The following table defines the meaning of the above table entries.

   0     This attribute MUST NOT be present in packet.
   0+    Zero or more instances of this attribute MAY be present in
         packet.
   0-1   Zero or one instance of this attribute MAY be present in
         packet.

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   1     Exactly one instance of this attribute MUST be present in
         packet.

5. Diameter Considerations

   This attribute is usable within either RADIUS or Diameter [RFC6733].
   Since the Attributes defined in this document will be allocated from
   the standard RADIUS type space, no special handling is required by
   Diameter entities.

6. Security Considerations

   In 6rd scenarios, both CE and BNG are within a provider network,
   which can be considered as a closed network and a lower security
   threat environment. A similar consideration can be applied to the
   RADIUS message exchange between BNG and the AAA server.

   Known security vulnerabilities of the RADIUS protocol are discussed
   in RFC 2607 [RFC2607], RFC 2865 [RFC2865], and RFC 2869 [RFC2869].
   Use of IPsec [RFC4301] for providing security when RADIUS is carried
   in IPv6 is discussed in RFC 3162 [RFC3162].

   A malicious user may use MAC address spoofing and/or dictionary
   attack on the shared 4rd password that has been preconfigured on the
   DHCPv6 server to get unauthorized 4rd configuration information.

   Security considerations for 4RD specific between 4RD CE and BNG are
   discussed in [I-D.ietf-softwire-4rd]. Furthermore, generic DHCPv6
   security mechanisms can be applied DHCPv6 intercommunication between
   4RD CE and BNG.

   Security considerations for the Diameter protocol are discussed in
   [RFC6733].

7. IANA Considerations

   This document requires the assignment of two new RADIUS Attributes
   Types in the "Radius Types" registry (currently located at
   http://www.iana.org/assignments/radius-types for the following
   attributes:

      o  4rd-Configuration     TBD1

   IANA should allocate the numbers from the standard RADIUS Attributes
   space using the "IETF Review" policy [RFC5226].

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8. Acknowledgments

   The authors would like to thank for valuable comments.

9. References

9.1. Normative References

   [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
             Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC2865] Rigney, C., Willens, S., Rubens, A., and W. Simpson,
             "Remote Authentication Dial In User Service (RADIUS)", RFC
             2865, June 2000.

   [RFC3162] Aboba, B., Zorn, G., and D. Mitton, "RADIUS and IPv6", RFC
             3162, August 2001.

   [RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., and
             M. Carney, "Dynamic Host Configuration Protocol for IPv6
             (DHCPv6)", RFC 3315, July 2003.

    [RFC4301]Kent, S. and K. Seo, "Security Architecture for the
             Internet Protocol", RFC 4301, December 2005.

   [RFC5080] Nelson, D. and DeKok A., "Common Remote Authentication Dial
             In User Service (RADIUS) Implementation Issues and
             Suggested Fixes", RFC 5080, December 2007.

   [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
             IANA Considerations Section in RFCs", RFC 5226, May 2008.

   [RFC6158] DeKok, A. and G. Weber, "RADIUS Design Guidelines", RFC
             6158, March 2011.

   [RFC6733] V. Fajardo, Ed., J. Arkko, J. Loughney, G. Zorn, Ed.,
             "Diameter Base Protocol", RFC 6733, October 2012.

   [I-D.ietf-softwire-4rd]
             R. Despres, et al., "IPv4 Residual Deployment via IPv6 - a
             unified Stateless Solution (4rd)", draft-ietf-softwire-4rd,
             working in progress.

9.2. Informative References

   [RFC2607] Aboba, B. and J. Vollbrecht, "Proxy Chaining and Policy
             Implementation in Roaming", RFC 2607, June 1999.

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   [RFC2869] Rigney, C., Willats, W., and P. Calhoun, "RADIUS
             Extensions", RFC 2869, June 2000.

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   Author's Addresses

   Sheng Jiang (Editor)
   Huawei Technologies Co., Ltd
   Q14 Huawei Campus, 156 BeiQi Road,
   ZhongGuan Cun, Hai-Dian District, Beijing 100085
   P.R. China
   EMail: jiangsheng@huawei.com

   Yu Fu
   Huawei Technologies Co., Ltd
   Q14 Huawei Campus, 156 BeiQi Road,
   ZhongGuan Cun, Hai-Dian District, Beijing 100085
   P.R. China
   EMail: eleven.fuyu@huawei.com

   Bing Liu
   Huawei Technologies Co., Ltd
   Q14 Huawei Campus, 156 BeiQi Road,
   ZhongGuan Cun, Hai-Dian District, Beijing 100085
   P.R. China
   EMail: leo.liubing@huawei.com