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Versions: 00 01 02 03 04 05 RFC 5192

Internet Engineering Task Force                                 S. Kumar
Internet-Draft                         Samsung India Software Operations
Expires: September 4, 2006                                     L. Morand
                                                      France Telecom R&D
                                                                A. Yegin
                                           Samsung Advanced Institute of
                                                              Technology
                                                          S. Madanapalli
                                       Samsung India Software Operations
                                                           March 3, 2006


               DHCP option for PANA Authentication Agents
                    draft-ietf-dhc-paa-option-01.txt

Status of this Memo

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   This Internet-Draft will expire on September 4, 2006.

Copyright Notice

   Copyright (C) The Internet Society (2006).

Abstract

   This document defines new Dynamic Host Configuration Protocol options
   that contain a list of domain names or IP addresses that can be



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   mapped to one or more of PANA Authentication Agents (PAA).  This is
   one of the many methods that a PANA Client (PaC) can use to locate
   PANA Authentication Agents (PAA).


Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  4
   3.  Requirements . . . . . . . . . . . . . . . . . . . . . . . . .  5
   4.  DHCP specification dependency  . . . . . . . . . . . . . . . .  6
   5.  PANA Authentication Agent DHCPv4 Option  . . . . . . . . . . .  7
     5.1.  PANA Authentication Agent Domain Name List . . . . . . . .  7
     5.2.  PANA Authentication Agent IPv4 Address List  . . . . . . .  8
   6.  PANA Authentication Agent DHCPv6 Options . . . . . . . . . . . 10
     6.1.  PANA Authentication Agent Domain Name List . . . . . . . . 10
     6.2.  PANA Authentication Agent IPv6 Address List  . . . . . . . 11
   7.  Client Operation . . . . . . . . . . . . . . . . . . . . . . . 13
     7.1.  DHCPv4 Client  . . . . . . . . . . . . . . . . . . . . . . 13
     7.2.  DHCPv6 Client  . . . . . . . . . . . . . . . . . . . . . . 13
   8.  DHCP Server Operation  . . . . . . . . . . . . . . . . . . . . 14
     8.1.  DHCPv4 Server  . . . . . . . . . . . . . . . . . . . . . . 14
     8.2.  DHCPv6 Server  . . . . . . . . . . . . . . . . . . . . . . 14
   9.  Security Considerations  . . . . . . . . . . . . . . . . . . . 15
   10. IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 16
   11. Normative References . . . . . . . . . . . . . . . . . . . . . 16
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 17
   Intellectual Property and Copyright Statements . . . . . . . . . . 18























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1.  Introduction

   The Protocol for carrying Authentication for Network Access (PANA)
   [1] defines a new Extensible Authentication Protocol (EAP) lower
   layer that uses IP between the protocol end points.

   The PANA protocol is run between a PANA Client (PaC) and a PANA
   Authentication Agent (PAA) in order to perform authentication and
   authorization for the network access service.

   This document specifies DHCPv4 option [2] and DHCPv6 option [7] that
   allow PANA client (PaC) to discover PANA Authentication Agents (PAA).
   This is one of the many methods for locating PAAs: manual
   configuration is an example of another one.





































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2.  Terminology

   This document uses the PANA terminology defined in [1].

   This document uses the DHCP terminology defined in [2] , [3] and[7].














































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3.  Requirements

   The keywords MUST, MUST NOT, REQUIRED, SHALL, SHALL NOT, SHOULD,
   SHOULD NOT, RECOMMENDED, MAY, and OPTIONAL, when they appear in this
   document, are to be interpreted as described in [4].














































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4.  DHCP specification dependency

   This document describes new options for DHCPv4 and DHCPv6 for
   obtaining a list of domain names or IP addresses to locate a PANA
   Authentication Agent.

   This document should be read in conjunction with the DHCPv4
   specifications [2] , [3] and DHCPv6 specification [7].

   Definitions for terms and acronyms not specifically defined in this
   document are defined in [2] , [3] and DHCPv6 specification [7].








































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5.  PANA Authentication Agent DHCPv4 Option

   This document defines a DHCPv4 option that carries either a 32-bit
   (binary) IPv4 address list or, preferably, a domain name list to be
   used by the PANA client to locate a PANA authentication Agent.

   The option has two encodings, specified by the encoding byte ('enc')
   that follows the code byte.  If the encoding byte has the value 0, it
   is followed by a list of domain names, as described below (Section
   5.1).  If the encoding byte has the value 1, it is followed by one or
   more IPv4 addresses (Section 5.2).  All implementations MUST support
   both encodings.  The 'option-length' field indicates the total number
   of octets in the option following the 'option-length' field,
   including the encoding byte.

5.1.  PANA Authentication Agent Domain Name List

   If the 'enc' byte has a value of 0, the encoding byte is followed by
   a sequence of labels, encoded according to Section 3.1 of RFC 1035
   [5], quoted below:

      Domain names in messages are expressed in terms of a sequence of
      labels.  Each label is represented as a one octet length field
      followed by that number of octets.  Since every domain name ends
      with the null label of the root, a domain name is terminated by a
      length byte of zero.  The high order two bits of every length
      octet must be zero, and the remaining six bits of the length field
      limit the label to 63 octets or less.  To simplify
      implementations, the total length of a domain name (i.e., label
      octets and label length octets) is restricted to 255 octets or
      less.

   RFC 1035 encoding was chosen to accommodate future internationalized
   domain name mechanisms.

   The option MAY contain multiple domain names, but these SHOULD refer
   to different NAPTR records, rather than different A records.  Domain
   names MUST be listed in order of preference.

   Use of multiple domain names is not meant to replace NAPTR and SRV
   records, but rather to allow a single DHCPv4 server to indicate
   multiple PANA Authentication Agents available in the same access
   network.

   Clients MUST support compression according to the encoding in Section
   4.1.4 of [5].

   If the length of the domain list exceeds the maximum permissible



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   within a single option (254 octets), then the domain list MUST be
   represented in the DHCP message as specified in [6].

   The DHCPv4 option for this encoding has the format shown in Fig. 1.

   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-length |      enc      |      ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                   PAA Domain Name List                        |
   |                              ...                              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
           Figure 1: DHCPv4 option for PAA Domain Name List

      option-code: OPTION_PANA_AGENT(TBD)

      option-length: Number of octets following the 'option-length'
      field, including the encoding byte, in octets; variable.

      enc: Encoding byte set to 0

      PAA Domain Name List: The domain names of the PANA Authentication
      Agents for the client to use.  The domain names are encoded
      according to Section 3.1 of RFC 1035 [5].

5.2.  PANA Authentication Agent IPv4 Address List

   If the 'enc' byte has a value of 1, the encoding byte is followed by
   a list of IPv4 addresses indicating one or more PANA Authentication
   Agents available to the PANA client.  PAAs MUST be listed in order of
   preference.

   The DHCPv4 option for this encoding has the format shown in Fig. 2.

   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-length |      enc      |      ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |              PAA IP Address                   |       ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
           Figure 2: DHCPv4 option for PAA IPv4 Address List

      option-code: OPTION_PANA_AGENT(TBD)

      option-length: Number of octets following the 'option-length'
      field, including the encoding byte in octets; Must be a multiple



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      of 4 plus one.

      enc: Encoding byte set to 1

      PAA IP Address: IPv4 address of a PAA for the PaC to use.  The
      PAAs are listed in the order of preference for use by the PaC.













































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6.  PANA Authentication Agent DHCPv6 Options

   This section defines two DHCPv6 options that describe a PANA
   Authentication Agent: one carries a list of domain names (Section
   6.1), the other a list of 128-bit (binary) IPv6 addresses (Section
   6.2).

      Since DHCPv6 does not suffer from a shortage of option codes, we
      avoid the encoding byte found in the DHCPv4 option for PAA
      (Section 5).  This makes the option shorter, easier to parse,
      simplifies appropriate word alignment for the numeric addresses
      and allows the DHCPv6 client to request either numeric or domain
      name options using the "option request option" (ORO).

   An implementation implementing this specification MUST support both
   options.

6.1.  PANA Authentication Agent Domain Name List

   The option length is followed by a sequence of labels, encoded
   according to Section 3.1 of RFC 1035 [3],quoted below:

      "Domain names in messages are expressed in terms of a sequence of
      labels.  Each label is represented as a one octet length field
      followed by that number of octets.  Since every domain name ends
      with the null label of the root, a domain name is terminated by a
      length byte of zero.  The high order two bits of every length
      octet must be zero, and the remaining six bits of the length field
      limit the label to 63 octets or less.  To simplify
      implementations, the total length of a domain name (i.e., label
      octets and label length octets) is restricted to 255 octets or
      less."

   RFC 1035 encoding was chosen to accommodate future internationalized
   domain name mechanisms.

   The option MAY contain multiple domain names, but these SHOULD refer
   to different NAPTR records, rather than different A records.  Domain
   names MUST be listed in order of preference.  Use of multiple domain
   names is not meant to replace NAPTR or SRV records, but rather to
   allow a single DHCP server to indicate PANA Authentication Agents
   operated by multiple providers.

   The DHCPv6 option for PANA Authentication Agent Domain Name List has
   the format shown in Fig. 3






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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-code             |     option-len                  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                  PAA Domain Name List                         |
      |                       ...                                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                 Figure 3: DHCPv6 option for PAA Domain Name List

      option-code: OPTION_PANA_AGENT_D (TBD).

      option-length: Length of the 'PAA Domain Name List' field in
      octets; variable.

      PAA Domain Name List: The domain names of the PANA Authentication
      Agents (PAA) for the client to use.  The domain names are encoded
      as specified in Section 8 ("Representation and use of domain
      names") of the DHCPv6 specification [7].

6.2.  PANA Authentication Agent IPv6 Address List

   This option specifies a list of IPv6 addresses indicating PANA
   Authentication Agent available to the client.PANA Authentication
   Agents MUST be listed in order of preference.

   The DHCPv6 option for PAA IPv6 Address List has the format shown in
   Fig. 4.























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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-code             |       option-len                |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                                                               |
      +                                                               +
      |                                                               |
      +                         PAA IPv6 Address                      +
      |                                                               |
      +                                                               +
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                                                               |
      +                                                               +
      |                                                               |
      +                         PAA IPv6 Address                      +
      |                                                               |
      +                                                               +
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                          ....                                 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
             Figure 4: DHCPv6 option for PAA IPv6 Address List

      option-code: OPTION_PANA_AGENT_A (TBD).

      option-length: Length of the 'options' field in octets; must be a
      multiple of 16.

      PANA IP Address: IPv6 address of a PAA for the client to use.The
      PAAs are listed in the order of preference for use by the client.

   If a client receives both the PAA Domain Name List and PAA IPv6
   Address List options, it SHOULD use first the PAA Domain Name List
   option.  The client MUST try the records in the order listed.  The
   client only resolves the subsequent domain names if attempts to
   contact the first one failed or denote a domain administratively
   prohibited by client policy.  Only if no PANA Authentication Agent in
   the Domain Name List can be resolved or reached, the client MAY use
   the PAA IPv6 Address List option.










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7.  Client Operation

7.1.  DHCPv4 Client

   The client requests PAA DHCPv4 Option in a Parameter Request List as
   described in [2] and [3].

   If the PAA DHCPv4 option provided in response by the DHCPv4 server
   contains multiple domain names, the client MUST try the records in
   the order listed.  The client only resolves the subsequent domain
   names if attempts to contact the first one failed or denote a domain
   administratively prohibited by client policy.

   If the PAA DHCPv4 option provided in response by the DHCPv4 server
   contains multiple IP addresses, the client MUST try the records in
   the order listed.

7.2.  DHCPv6 Client

   A DHCPv6 client may request either or both PAA domain name list and
   PAA IPv6 address list options in an Options Request Option (ORO) as
   described in the DHCPv6 specification [7].





























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8.  DHCP Server Operation

8.1.  DHCPv4 Server

   If a DHCPv4 server is configured with both PAA domain name list and
   PAA IP address list, the DHCPv4 server should responds to the request
   with the domain name list to be used by the PANA client.

   A DHCP server MUST NOT mix the two list types (domain names and IPv4
   address) in the same DHCPv4 message, even if it sends two different
   instances of the same option.

8.2.  DHCPv6 Server

   A DHCPv6 server MAY send a DHCPv6 client one or both of the PAA
   Domain Name List and PAA IPv6 Address List options.

   If a DHCPv6 client requests both options in an ORO and the server is
   configured for both, the DHCPv6 server MAY send a DHCPv6 client only
   one of these options and that option SHOULD be the PAA Domain Name
   List.

   If a DHCPv6 client requests only the PAA IPv6 Address List option and
   the DHCPv6 server is configured with both options, the server MUST
   send a DHCPv6 client the PAA IPv6 Address List option and MAY send a
   the PAA Domain Name List (see [7]).

   The following table summarizes the DHCPv6 server's responses:

      Client sends in ORO        Domain Name List    IPv6 Address List
      -----------------------------------------------------------------
      Neither option                   SHOULD              MAY
      PAA Domain Name List             SHOULD              MAY
      PAA IPv6 Address List            MAY                 MUST
      Both options                     SHOULD              MAY
















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9.  Security Considerations

   The security considerations in [2] , [3] and [7] apply.  If an
   adversary manages to modify the response from a DHCP server or insert
   its own response, a PANA Client could be led to contact a rogue PANA
   Agent, possibly one that then intercepts call requests or denies
   service.












































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10.  IANA Considerations

   IANA assignment for the following DHCPv4 option code is needed.

   Option  Name                 Value
   ----------------------------------
   OPTION_PAA_AGENT              TBD

   The following option codes for PANA Authentication Agent DHCPv6
   options must be assigned by IANA.

      Option  Name                 Value       Described in
      -----------------------------------------------------
      OPTION_PAA_AGENT_D            TBD         Section 6.1
      OPTION_PAA_AGENT_A            TBD         Section 6.2


11.  Normative References

   [1]  Forsberg, D., Ohba, Y., Patil, B., Tschofenig, H., and A. Yegin,
        "Protocol for Carrying Authentication for Network Access (PANA),
        draft-ietf-pana-pana-08 (work in progress)", Novemeber 2005.

   [2]  Droms, R., "Dynamic Host Configuration Protocol", RFC 2131,
        March 1997.

   [3]  Alexander, S. and R. Droms, "DHCP Options and BOOTP Vendor
        Extensions", RFC 2132, March 1997.

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

   [5]  Mockapetris, P., "Domain names - implementation and
        specification", STD 13, RFC 1035, November 1987.

   [6]  Lemon, T. and S. Cheshire, "Encoding Long Options in the Dynamic
        Host Configuration Protocol (DHCPv4)", RFC 3396, November 2002.

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










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Authors' Addresses

   Suraj Kumar
   Samsung India Software Operations
   No. 66/1, BAGMANE TECH PARK, C V RAMAN NAGAR
   Bangalore
   India

   Phone: +91 80 41819999
   Email: suraj.kumar@samsung.com


   Lionel Morand
   France Telecom R&D
   38-40 rue du general Leclerc
   Issy-les-Moulineaux, F-92130
   France

   Phone: +33 1 4529 6257
   Email: lionel.morand@francetelecom.com


   Alper E. Yegin
   Samsung Advanced Institute of Technology
   75 West Plumeria Drive
   San Jose, CA  95134
   USA

   Phone: +1 408 544 5656
   Email: alper.yegin@samsung.com


   Syam Madanapalli
   Samsung India Software Operations
   No. 66/1, BAGMANE TECH PARK, C V RAMAN NAGAR
   Bangalore
   India

   Phone: +91 80 41819999
   Email: syam@samsung.com











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Intellectual Property Statement

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Copyright Statement

   Copyright (C) The Internet Society (2006).  This document is subject
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Acknowledgment

   Funding for the RFC Editor function is currently provided by the
   Internet Society.




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