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Versions: 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 RFC 6784

Network Working Group                                          S. Sakane
Internet-Draft                                             Cisco Systems
Intended status: Standards Track                             M. Ishiyama
Expires: January 11, 2013                            Toshiba Corporation
                                                           July 10, 2012


                      Kerberos Options for DHCPv6
               draft-sakane-dhc-dhcpv6-kdc-option-17.txt

Abstract

   This document defines new four options for the Dynamic Host
   Configuration Protocol for IPv6 (DHCPv6), options which carry
   configuration information for Kerberos.

Status of this Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
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   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on January 11, 2013.

Copyright Notice

   Copyright (c) 2012 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.




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   This document may contain material from IETF Documents or IETF
   Contributions published or made publicly available before November
   10, 2008.  The person(s) controlling the copyright in some of this
   material may not have granted the IETF Trust the right to allow
   modifications of such material outside the IETF Standards Process.
   Without obtaining an adequate license from the person(s) controlling
   the copyright in such materials, this document may not be modified
   outside the IETF Standards Process, and derivative works of it may
   not be created outside the IETF Standards Process, except to format
   it for publication as an RFC or to translate it into languages other
   than English.


Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Conventions used in this document  . . . . . . . . . . . . . .  4
   3.  Kerberos Options . . . . . . . . . . . . . . . . . . . . . . .  5
     3.1.  Kerberos Principal Name Option . . . . . . . . . . . . . .  5
     3.2.  Kerberos Realm Name Option . . . . . . . . . . . . . . . .  6
     3.3.  Kerberos Default Realm Name Option . . . . . . . . . . . .  6
     3.4.  Kerberos KDC Option  . . . . . . . . . . . . . . . . . . .  6
   4.  Client and Server Operation  . . . . . . . . . . . . . . . . .  9
     4.1.  KDC discovery for a client . . . . . . . . . . . . . . . .  9
   5.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 10
   6.  Security Considerations  . . . . . . . . . . . . . . . . . . . 11
   7.  Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 12
   8.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 13
     8.1.  Normative References . . . . . . . . . . . . . . . . . . . 13
     8.2.  Informative References . . . . . . . . . . . . . . . . . . 13
   Appendix A.  Why DNS is not acceptable in some environments  . . . 14
   Appendix B.  An example of the operation of the client . . . . . . 17
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 19


















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1.  Introduction

   Kerberos Version 5 [RFC4120] is a trusted third-party authentication
   system.  Each organization wishing to use Kerberos establishes its
   own "realm" and each client is registered as part of that realm.  At
   least one Key Distribution Center (KDC) is required for the operation
   of a Kerberos realm.

   When a client wishes to communicate with, and be authenticated to, a
   Kerberos application server (also a client of the KDC), the client
   identifies itself, and its realm, to the KDC and acquires a
   credential from the KDC.  The client then presents the credential to
   the Kerberos application server which can use the credential to
   authenticate the client.  The client needs to know at least one IP
   address for a KDC in order to initiate this process.

   One example of the application of this protocol is as follows.  A
   student might want to use a shared, public workstation, one that is
   not configured for Kerberos.  If there is a mechanism for the
   workstation to obtain a realm name and IP address for a KDC, then a
   student need only input a user-id and pass phrase to be able to use
   Kerberos.

   The Kerberos V5 specification [RFC4120] defines the use of DNS SRV
   records [RFC2782] for KDC discovery.  Some systems, such as
   industrial systems, do not use DNS.  Such systems already have their
   own name spaces and their own name resolution systems, including pre-
   configured mapping tables for devices, and do not use Fully Qualified
   Domain Names.  However, many of these systems do use DHCP.

   Adding a DNS server to such systems may decrease the reliability of
   the system and increase the management cost (see Appendix A).  In
   such an environment, another mechanism is needed to provide an IP
   address for the KDC.  For the PacketCable Architecture [PCARCH],
   RFC 3634 [RFC3634] defines the KDC Server Address sub-option for the
   DHCPv4 CableLabs Client Configuration option.  However, a mechanism
   is still needed to provide a realm name and an IPv6 address, one
   which does not depend on any external architecture.

   This document defines a Kerberos option for DHCPv6 which provides a
   realm name and/or a list of KDC IP addresses.  This option does not
   replace or modify any of the existing methods for obtaining this
   information.








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2.  Conventions used in this document

   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 RFC 2119 [RFC2119].

   It is assumed that the readers are familiar with the terms and
   concepts described in DHCPv6 [RFC3315].











































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3.  Kerberos Options

   This document defines four DHCP configuration parameters for
   Kerberos.

      Kerberos Principal Name Option

      Kerberos Realm Name Option

      Kerberos Default Realm Name Option

      Kerberos KDC Option

   This section describes the format of each option, and the usage of
   each field in that option.

   With the exception of the Kerberos KDC Option, none of these options
   may appear more than once in a DHCPv6 message.

3.1.  Kerberos Principal Name Option

   The Kerberos Principal Name Option carries the name of a Kerberos
   principal.  This is sent by the client to the DHCPv6 server which MAY
   use it to select a specific set of configuration parameters, either
   for a client or for a Kerberos application server.

   The format of the Kerberos Principal Name option is:


      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_KRB_PRINCIPAL_NAME   |          option-len           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      :                                                               :
      :                        principal-name                         :
      :                       (variable length)                       :
      :                                                               :
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   o  option-code (16-bit): OPTION_KRB_PRINCIPAL_NAME (TBD by IANA)

   o  option-len (16-bit): length of the principal-name field.

   o  principal-name (variable): a client principal name.  The encoding
      of the principal-name field MUST conform to the definition of
      "PrincipalName" in section 5.2.2 of RFC 4120 [RFC4120].



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3.2.  Kerberos Realm Name Option

   The Kerberos Realm Name Option carries a Kerberos realm name.  A
   DHCPv6 client uses this option to specify to a DHCPv6 server which
   realm the client wants to access.

   The format of the Kerberos Realm Name option is:


      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_KRB_REALM_NAME     |          option-len           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      :                                                               :
      :                          realm-name                           :
      :                       (variable length)                       :
      :                                                               :
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   o  option-code (16-bit): OPTION_KRB_REALM_NAME (TBD by IANA)

   o  option-len (16-bit): the length of the realm-name field in octets.

   o  realm-name (variable): a realm-name.  The encoding of the realm-
      name field MUST conform to the definition of "Realm" in section
      5.2.2 of RFC 4120 [RFC4120].

3.3.  Kerberos Default Realm Name Option

   The Kerberos Default Realm Name Option is used to specify a default
   realm name for the Kerberos system.  A DHCPv6 server uses this option
   to specify the default realm name to both clients and Kerberos
   application servers.

   The option-code of this option is OPTION_KRB_DEFAULT_REALM_NAME.  The
   format and usage of the option-len and realm-name fields are
   identical to those for the Kerberos Realm Name Option.

3.4.  Kerberos KDC Option

   The Kerberos KDC Option is used to provide configuration information
   about a KDC.

   The format of the Kerberos KDC Option is:





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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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         OPTION_KRB_KDC        |          option-len           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |           Priority            |            Weight             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Transport Type|          Port Number          |               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+               |
      |                                                               |
      |                                                               |
      |                       KDC IPv6 address        +---------------+
      |                                               |               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+               :
      :                                                               :
      :                          realm-name                           :
      :                       (variable length)                       :
      :                                                               :
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   o  option-code (16-bit): OPTION_KRB_KDC (TBD by IANA)

   o  option-len (16-bit): 23 + the length of the realm-name field in
      octets.

   o  Priority (16-bit): see the description of Weight field.

   o  Weight (16-bit): the Priority and Weight fields provide a hint to
      the client as to which KDC to select.  The usage of the Priority
      and Weight values MUST follow the specification for DNS SRV
      [RFC2782].

   o  Transport Type (8-bit): The Transport Type specifies the transport
      protocol used for Kerberos.  Kerberos [RFC4120] defines UDP and
      TCP transports.  Exchanges over TCP are further described in
      [RFC5021] while the transport of Kerberos over TLS is described in
      [RFC6251].

   The transport type is defined in below.


        Value    Transport Type
        ----     --------------
        0        Reserved
        1        UDP
        2        TCP
        3        TLS



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        4-254    Unassigned
        255      Reserved


   o  Port Number (16-bit): the port number on which the KDC listens.

   o  KDC IPv6 address (128-bit): the IPv6 address of the KDC.

   o  realm-name (variable): the name of the realm for which the
      specified KDC provides service.  The encoding of the realm- name
      field MUST conform to the definition of "Realm" in section 5.2.2
      of RFC 4120 [RFC4120].







































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4.  Client and Server Operation

   This section describes the operations of client and server.  It
   assumes that the client has been configured with a principal name.

   If a client requires a realm name, the client MUST send a DHCPv6
   Option Request option (ORO) specifying the Kerberos Default Realm
   Name Option.  The DHCPv6 server responds with a Reply message
   containing a Kerberos Default Realm Name Option.

   If a client requires configuration parameters for a KDC, the client
   MUST send a DHCPv6 ORO specifying the Kerberos KDC Option.  The
   client MAY send a Kerberos Principal Name Option.  The client MAY
   send a Kerberos Realm Name Option.

   The DHCPv6 server replies with one or more sets of configuration
   parameters for a Kerberos KDC.  If the client has specified either a
   Kerberos Principal Name Option or a Kerberos Realm Name Option, then
   the DHCPv6 server MAY use those parameters to select a specific sets
   of configuration parameters.

   Where the server replies with more than one set of configuration
   paramers, the usage of priority and weight fields by the client MUST
   follow the specification for DNS SRV [RFC2782].

   The client MAY include other options with data values as hints to the
   DHCPv6 server about parameter values the client would like to have
   returned; this is specified in section 18.1.5 of RFC 3315 [RFC3315].

4.1.  KDC discovery for a client

   When a client implements both the DNS method defined by section
   7.2.3.2 of [RFC4120] and the DHCP method defined by this document,
   the choice of method is determined by local policy.  The
   administrator of the realm MUST define the method as part of the
   configuration of the client before the client is installed.

   When no criteria have been specified and the client could get the
   Kerberos information from either the DNS server or the DHCPv6 server,
   then the information from DNS SHOULD be preferred.











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5.  IANA Considerations

   IANA is requested to assign four option codes from the "DHCPv6
   Options Codes" registry for the following:

      OPTION_KRB_PRINCIPAL_NAME

      OPTION_KRB_REALM_NAME

      OPTION_KRB_DEFAULT_REALM_NAME

      OPTION_KRB_KDC

   IANA is requested to create a sub-registry of Kerberos Message
   Transport Type, under the Kerberos Parameters Registry.  The initial
   entries are described in section 3.4.

   The assignment of future entries is by "IETF Consensus" policy as
   described in BCP 26 [RFC5226].  The RFC specifies the symbolic name
   of such entries which are assigned numeric codes by IANA once
   publication is approved.






























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6.  Security Considerations

   The security considerations in RFC 3315 [RFC3315] apply.

   DHCPv6 messages can be modified in transit.  If an adversary modifies
   the response from a DHCPv6 server or injects its own response, a
   client may be led into contacting a malicious KDC.  Both cases are
   categorized as a Denial of Service (DoS) attack.  However, a
   malicious KDC does not know the shared key and so is unable to
   proceed any further with the exchange.  If a client receives a
   response from such a KDC, the client can use the shared key to detect
   that the message originates from a malicious KDC.

   A shared, unconfigured workstation may obtain its KDC information,
   and default realm, via DHCPv6.  Such a workstation may not have a
   host or other service key, and thus be unable to validate the Ticket-
   Granting Ticket issued by the KDC.  A modified DHCPv6 response would
   then result in the workstation talking to a malicious KDC and be
   unable to detect that has happened.  This in turn could allow access
   by unauthorized users.

   To minimize potential vulnerabilities, a client SHOULD use DHCPv6
   authentication as defined in section 21 of RFC 3315 [RFC3315].

   Kerberos information may be manually configured into the client
   before requesting information from DHCPv6.  Manual configuration of
   the device SHOULD be preferred to configuration via the DHCPv6
   server.























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7.  Acknowledgments

   The authors are very grateful to Nobuo Okabe and Shigeya Suzuki.
   They contributed the explanation as to why DNS is inappropriate for
   some industry networks; this is included as an appendix to this
   document.  Ted Lemon made many suggestions to improve DHCP aspects of
   this specification.  Ken'ichi Kamada and Yukiyo Akisada contributed
   to the initial work on this document.  Tom Petch helped to improve
   the readability of this document.  The authors also thank Jeffrey
   Hutzelman, Kazunori Miyazawa, Kensuke Hosoya, Nicolas Williams,
   Nobumichi Ozoe, Sam Hartman, and Stephen Farrell.  They made valuable
   comments and suggestions.







































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8.  References

8.1.  Normative References

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

   [RFC2782]  Gulbrandsen, A., Vixie, P., and L. Esibov, "A DNS RR for
              specifying the location of services (DNS SRV)", RFC 2782,
              February 2000.

   [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.

   [RFC4120]  Neuman, C., Yu, T., Hartman, S., and K. Raeburn, "The
              Kerberos Network Authentication Service (V5)", RFC 4120,
              July 2005.

   [RFC5021]  Josefsson, S., "Extended Kerberos Version 5 Key
              Distribution Center (KDC) Exchanges over TCP", RFC 5021,
              August 2007.

   [RFC5226]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
              IANA Considerations Section in RFCs", BCP 26, RFC 5226,
              May 2008.

8.2.  Informative References

   [PCARCH]   CableLabs, "PacketCable 1.0 Architecture Framework
              Technical Report", December 1999, <http://
              www.packetcable.com/downloads/specs/
              pkt-tr-arch-v01-991201.pdf>.

   [RFC3634]  Luehrs, K., Woundy, R., Bevilacqua, J., and N. Davoust,
              "Key Distribution Center (KDC) Server Address Sub-option
              for the Dynamic Host Configuration Protocol (DHCP)
              CableLabs Client Configuration (CCC) Option", RFC 3634,
              December 2003.

   [RFC6251]  Josefsson, S., "Using Kerberos Version 5 over the
              Transport Layer Security (TLS) Protocol", RFC 6251,
              May 2011.








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Appendix A.  Why DNS is not acceptable in some environments


   1. Summary

      - This appendix gives reasons why DHCP-based KDC discovery
        is more appropriate for industrial systems
        than DNS-based KDC discovery (as described
        in RFC4120 - the "RFC4120-way").

      - Industrial systems have their own name spaces and
        naming systems which are not based on FQDN and DNS.

      - DHCP-based KDC discovery is more efficient because
        reducing the number of servers reduces the number of
        messages, improves reliability and reduces management cost.

   2. Background (what are industrial systems?)

      Industrial systems are
      used to control plants, factories, buildings, etc.
      They may incorporate a large number of devices, i.e. sensors and
      actuators, commonly referred to as field devices.

      These field devices have the following characteristics:
      1) Though physically large, they have limited resources,
         e.g. processing capability, memory size,
         footprint, power consumption and user interface.
      2) They are controlled, as an I/O, by an administrative
         device, usually referred to as a controller, using a legacy
         communication technology.
      3) Since they are on I/O buses, not networks,
         the security of the communications has not been considered.

   3. High-level goals

   3.1. IP and security can enhance industrial systems.

      Our goal is to introduce the latest IP-based networking technology
      into field devices, something which will enhance the entire
      system.
      1) Network architecture (= IP technology) can enhance
         the systems, including the field devices.
      2) The field devices will be connected to a network and
         not be I/O devices anymore, and so will require security.

   3.2. Auto-configuration benefits industrial systems.




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      Auto-configuration of large systems, such as
      industrial systems is important when introducing new technology or
      capabilities:

      1) It reduces the engineering cost when installing/configuring
         a large number of field devices over a large area.
         The size of a plant, the size of an industrial system and
         the number of field devices are growing.

         - A large process automation system has
           about 20,000 field devices over a 2*2km area

           References:
              - http://www.process-worldwide.com/fachartikel/pw_facha
                rtikel_2699276.html

         - A distributed process automation systems has
           about 30,000 field devices on 26 distributed sites
           over a 30*30km area.

           References:
              - http://www.mikrocentrum.nl/FilesPage/3462/Presentatie
                %20C3-1.pdf
              - http://www.nam.nl/home/Framework?siteId=nam-en&FC2=/n
                am-en/html/iwgen/algemeen/zzz_lhn.html&FC3=/nam-en/ht
                ml/iwgen/algemeen/over_de_nam.html

         - A large building automation system has
           170,000 control points for 16,500 field devices in
           729,000 sq. meters (7.8 million sq. ft.) building complex.

           References:
              - http://www.echelon.com/company/press/2003/echelon_mor
                i.htm

      2) It reduces the chance of human error.

      3) It makes disaster-recovery easier.

   3.3. Security mechanisms for resource-limited devices are
        needed.

      Kerberos-based security is suitable for resource-limited devices,
      i.e. field devices, since it avoids
      public key cryptography (except when using PKINIT).

   4. Some industrial systems do not use DNS.




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      Field devices have used multiple technologies (see
      Section 6) but do not use DNS because they already have
      their own namespaces and naming systems (even though IP is
      in use, in part).

      For example, "tag" is the common logical identifier for process
      automation systems and Device ID is the common logical identifier
      for building automation systems.
      (You may think those names are not so abstracted, though....)

   5. KDC discovery with DHCP is more suitable than with DNS.

      If Kerberos is introduced into field devices,
      auto-configuration could be achieved by:
      1) Learning DNS address(es) from DHCP
      2) Learning KDC address(es) from DNS, using the RFC4120-way.
      However, DNS will be used by the Kerberos-related part only;
      most applications will not use DNS.

      If DHCP can advertise KDC-related information,
      then:
      1) the number of messages handled by the field devices is reduced,
         reducing the footprint of the field devices.
      2) the number of servers is reduced, reducing
         the management cost of the systems.

   6. References

      Field devices have used many technologies.
      For example:
      - FOUNDATION Fieldbus (http://www.fieldbus.org/)
      - PROFIBUS (http://www.profibus.com/)
      - BACnet (http://www.bacnet.org/)
      - LonWorks (http://www.echelon.co.jp/products/lonworks.html)
      - Modbus (http://www.modbus.org/)

      Wikipedia also provides information about the communications
      technology of field devices:
      - http://en.wikipedia.org/wiki/Fieldbus
      - http://en.wikipedia.org/wiki/BACnet
      - http://en.wikipedia.org/wiki/LonWorks










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Appendix B.  An example of the operation of the client

   When no criteria have been specified and the client could get the
   Kerberos information from either the DNS server or the DHCPv6 server,
   then the information from DNS should be preferred.  The following is
   the guideline for the client in such an environment.













































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                               No Resp. or
               +------------+  DNS Info. +-----------+ No Resp.
     Start --> | Ask DHCP(1)| ---------> | Ask DNS(3)| ------>
               +------------+            +-----------+     Terminate(4)
                /          \                      \
      Only KRB /            \ DNS and              \ KRB Info.
        Info. /              \ KRB Info.            \
             /                \                      \
            |                  |                       |
            |                  V                       |
            V     No Ans.  +-----------+  KRB Info.    V
       Use Info. <-------- | Ask DNS(6)| ---------> Use Info.
       from DHCP           +-----------+            from DNS
      (2), (7)                                      (5), (8)

        Abbreviations:
          Resp.: Response
          Info.: Information
          KRB  : Kerberos


   1) Initially, the client requests both DNS and Kerberos information
      from the DHCPv6 server.

   2) If the DHCPv6 server replies with Kerberos information and not
      with DNS information, then the client uses that information.

   3) If the DHCPv6 server does not reply or replies with only DNS
      information, then the client requests Kerberos information from
      the DNS server.

   4) If the client gets no response or no Kerberos information from the
      DNS server, then the client terminates the process.

   5) If the client gets Kerberos information from the DNS server, then
      the client uses that information.

   6) If, as the result of (1), the DHCPv6 server replies with both DNS
      and Kerberos information, then the client requests Kerberos
      information from the DNS server.

   7) If the client gets no response from the DNS server, then the
      client uses the Kerberos information from the DHCPv6 server.

   8) If, as the result of (6), the DNS server replies with Kerberos
      information, then the client uses the information from the DNS
      server and not that from the DHCPv6 server.




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Internet-Draft         Kerberos Options for DHCPv6             July 2012


Authors' Addresses

   Shoichi Sakane
   Cisco Systems
   9-7-1 Akasaka
   Minato-ku, Tokyo  107-6227
   Japan

   Email: ssakane@cisco.com


   Masahiro Ishiyama
   Toshiba Corporation
   1, komukai-toshiba-cho, Saiwai-ku,
   Kawasaki, Kanagawa  212-8582
   Japan

   Email: masahiro@isl.rdc.toshiba.co.jp

































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