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PROPOSED STANDARD
Errata Exist
Network Working Group                                          D. Provan
Request for Comments: 2241                                  Novell, Inc.
Category: Standards Track                                  November 1997



               DHCP Options for Novell Directory Services


Status of this Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.


Copyright Notice

   Copyright (C) The Internet Society (1997).  All Rights Reserved.


Abstract

   This document defines three new DHCP options for delivering
   configuration information to clients of the Novell Directory
   Services. The first option carries a list of NDS servers. The second
   option carries the name of the client's NDS tree. The third carries
   the initial NDS context. These three options provide an NDS client
   with enough information to connect to an NDS tree without manual
   configuration of the client.

1. Introduction

   Novell Directory Services is a distributed, replicated, hierarchical
   database of objects representing network resources such as nodes,
   services, users, and applications. An NDS client must be able to
   locate an NDS server in order to authenticate itself to the network
   and gain access to the database. In addition, the node's user is
   better served if the NDS client's attention is focused on the area of
   the NDS database likely to be of the most interest to the user.  This
   specification describes DHCP options [1] that carry NDS information
   to TCP/IP clients of NDS. The first option, the NDS Servers Option,
   carries a list of NDS servers. The other two options, the NDS Tree
   Name Option and the NDS Context Option, provide the client with a
   default context within the NDS database.




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RFC 2241                     DHCP Options                  November 1997


   The NDS Tree Name Option and the NDS Context Option carry 16-bit
   Unicode text encoded into an octet stream using UTF-8 [4]. A complete
   DHCP implementation can represent of the entire Unicode character set
   supported by NDS. At the same time, 7-bit ASCII text is unchanged by
   the UTF-8 transformation. In environments where the NDS tree name and
   context are restricted to the range of 7-bit ASCII characters, ASCII-
   only DHCP clients and servers can support these options by using the
   ASCII text as the UTF-8 encoded data.

   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. [2]

2. NDS Servers Option

   This option specifies one or more NDS servers for the client to
   contact for access to the NDS database. Servers SHOULD be listed in
   order of preference.

   The code for this option is 85. The minimum length of this option is
   4 octets, and the length MUST be a multiple of 4.

      Code   Len        Address 1               Address 2
     +-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+--
     | 85  |  n  |  a1 |  a2 | a3  |  a4 |  a1 |  a2 |  a3 |  a4 |  ...
     +-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+--


3. NDS Tree Name Option

   This option specifies the name of the NDS tree the client will be
   contacting. NDS tree names are 16-bit Unicode strings. For
   transmission in the NDS Tree Name Option, an NDS tree name is
   transformed into octets using UTF-8. The string should NOT be zero
   terminated.

   The code for this option is 86. The maximum possible length for this
   option is 255 bytes.

       Code Len  NDS Tree Name
      +----+----+----+----+----+----+--
      | 86 | n  | c1 | c2 | c3 | c4 |  ...
      +----+----+----+----+----+----+--








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RFC 2241                     DHCP Options                  November 1997


4. NDS Context Option

   This option specifies the initial NDS context the client should use.
   NDS contexts are 16-bit Unicode strings. For transmission in the NDS
   Context Option, an NDS context is transformed into octets using UTF-
   8. The string should NOT be zero terminated.

   A single DHCP option can only contain 255 octets. Since an NDS
   context name can be longer than that, this option can appear more
   than once in the DHCP packet. The contents of all NDS Context options
   in the packet should be concatenated as suggested in the DHCP
   specification [3, page 24] to get the complete NDS context. A single
   encoded character could be split between two NDS Context Options.

   The code for this option is 87. The maximum length for each instance
   of this option is 255, but, as just described, the option may appear
   more than once if the desired NDS context takes up more than 255
   octets. Implementations are discouraged from enforcing any specific
   maximum to the final concatenated NDS context.

       Code Len  Initial NDS Context
      +----+----+----+----+----+----+--
      | 87 | n  | c1 | c2 | c3 | c4 |  ...
      +----+----+----+----+----+----+--

5. References

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

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

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

   [4] Yergeau, F., "UTF-8, a transformation format of Unicode and
       ISO 10646", RFC-2044, October 1996

6. Security Considerations

   DHCP currently provides no authentication or security mechanisms.
   Potential exposures to attack are discussed in section 7 of the DHCP
   protocol specification [3]. In particular, these DHCP options allow
   an unauthorized DHCP server to misdirect an NDS client to a
   nonexistent NDS server or even a spoof NDS server. These threats are
   similar to what NDS faces during normal operations in its native IPX
   environment.



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RFC 2241                     DHCP Options                  November 1997


7. Author's Address

   Don Provan
   Novell, Inc.
   2180 Fortune Drive
   San Jose, California, 95131

   Phone: +1 408 577 8440

   EMail: donp@Novell.Com









































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RFC 2241                     DHCP Options                  November 1997


8.  Full Copyright Statement

   Copyright (C) The Internet Society (1997).  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
   the copyright notice or references to the Internet Society or other
   Internet organizations, except as needed for the purpose of
   developing Internet standards in which case the procedures for
   copyrights defined in the Internet Standards process must be
   followed, or as required to translate it into languages other than
   English.

   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
   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
























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