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Versions: 00 01 RFC 4075

Network Working Group                     Vijayabhaskar A Kalusivalingam
Internet-Draft                                           Hewlett-Packard
Expires: May 2004                                               Nov 2003


      Simple Network Time Protocol Configuration Option for DHCPv6
                   draft-ietf-dhc-dhcpv6-opt-sntp-00

Status of this Memo

   This document is an Internet-Draft and is in full conformance with
   all provisions of Section 10 of RFC2026.

   Internet-Drafts are working documents of the Internet Engineering
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   This Internet-Draft will expire on May, 2004.

Copyright Notice

   Copyright (C) The Internet Society (2003).  All Rights Reserved.

Abstract

   This document describes a new DHCPv6 option for passing a list of
   SNTP server addresses to a client.

1. Introduction

   This document describes a new option called SNTP [3] servers Option
   for passing information about SNTP servers in DHCPv6 [1].

2. 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 RFC 2119 [2]






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3. Terminology

   This document uses terminology specific to IPv6 and DHCPv6 as defined
   in "Terminology" section of the DHCPv6 specification.

4. Simple Network Time Protocol (SNTP) Servers option

   The Simple Network Time Protocol Servers option provides a list of
   one or more IPv6 addresses of SNTP [3] servers available to the
   client for synchronization. The SNTP servers SHOULD be listed in
   the order of preference.  The clients use these SNTP servers to
   synchronize their system time to that of the standard time servers.

   The format of the Simple Network Time Protocol Servers option is as
   shown below:

       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_SNTP_SERVERS       |        option-len            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                                                               |
      |                  SNTP server (IPv6 address)                   |
      |                                                               |
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                                                               |
      |                  SNTP server (IPv6 address)                   |
      |                                                               |
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                              ...                              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   option-code:   OPTION_SNTP_SERVERS (tbd)

   option-len:  Length of the 'SNTP server'  fields in octets; It must be
         a multiple of 16

   SNTP server:    IPv6 address of SNTP server

5. Appearance of these options

   The SNTP servers option MUST NOT appear in other than the following
   messages:  Solicit, Advertise, Request, Renew, Rebind,
   Information-Request and Reply.

   The option number for this option MAY appear in the Option Request
   Option [1] in the following messages:  Solicit, Request, Renew,
   Rebind, Information-Request and Reconfigure.






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6. Security Considerations

   The SNTP servers option may be used by an intruder DHCPv6 server to
   cause DHCPv6 clients to contact a rogue SNTP server, resulting in
   invalid synchronization of time in client and finally leading to
   time critical applications running inaccurately in client machine.
   The time accuracy can be crucial to some security algorithms. For
   example, it may cause expired certificates to gain a new life, making
   the applications running on the client machine less secure. It can
   even cause clients to set their time incorrectly, making them
   vulnerable to replay attacks in protocols that use time stamps to
   detect replays.

   To avoid attacks through these options, the DHCPv6 client SHOULD use
   authenticated DHCPv6 (see "Authentication of DHCP messages" section
   in the DHCPv6 specification [1]).

7. IANA Considerations

   IANA is requested to assign an option code to the following options
   from the option-code space defined in "DHCPv6 Options" section of the
   DHCPv6 specification [1].

   Option Name         Value    Described in
   OPTION_SNTP_SERVERS   tbd     Section 4.

8. Normative References

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

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

9. Informative References

   [3]  D. Mills.  Simple Network Time Protocol (SNTP) Version 4 for
        IPv4, IPv6 and OSI.  Request for Comments (Informational) 2030,
        Internet Engineering Task Force, October 1996.

Author's Address

   Vijayabhaskar A Kalusivalingam
   Hewlett-Packard STSD-I
   29, Cunningham Road
   Bangalore - 560052
   India

   Phone: +91-80-2053085
   E-Mail: vijayak@india.hp.com






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Full Copyright Statement

   Copyright (C) The Internet Society (2003).  All Rights Reserved.

   This document and translations of it may be copied and furnished to
   others, and derivative works that comment on or otherwise explain it
   or assist in its implementation may be prepared, copied, published
   and distributed, in whole or in part, without restriction of any
   kind, provided that the above copyright notice and this paragraph are
   included on all such copies and derivative works.  However, this
   document itself may not be modified in any way, such as by removing
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   The limited permissions granted above are perpetual and will not be
   revoked by the Internet Society or its successors or assigns.

   This document and the information contained herein is provided on an
   "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
   TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
   BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
   HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
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Acknowledgement

   Funding for the RFC Editor function is currently provided by the
   Internet Society.  Thanks to the DHC Working Group for their time and
   input into the specification.  In particular, thanks to (in
   alphabetical order) Bernie Volz, Jim Bound, Margaret Wasserman, Ralph
   Droms, Robert Elz and Thomas Narten for their thorough review.























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