Network Working Group                                           S. Drach
Request for Comments: 2485                              Sun Microsystems
Category: Standards Track                                   January 1999



    DHCP Option for The Open Group's User Authentication Protocol

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 (1999).  All Rights Reserved.

Abstract

  This document defines a DHCP [1] option that contains a list of
  pointers to User Authentication Protocol servers that provide user
  authentication services for clients that conform to The Open Group
  Network Computing Client Technical Standard [2].

Introduction

  The Open Group Network Computing Client Technical Standard, a product
  of The Open Group's Network Computing Working Group (NCWG), defines a
  network computing client user authentication facility named the User
  Authentication Protocol (UAP).

  UAP provides two levels of authentication, basic and secure.  Basic
  authentication uses the Basic Authentication mechanism defined in the
  HTTP 1.1 [3] specification.  Secure authentication is simply basic
  authentication encapsulated in an SSLv3 [4] session.

  In both cases, a UAP client needs to obtain the IP address and port
  of the UAP service.  Additional path information may be required,
  depending on the implementation of the service.  A URL [5] is an
  excellent mechanism for encapsulation of this information since many
  UAP servers will be implemented as components within legacy HTTP/SSL
  servers.






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RFC 2485          DCHP Option for the Open Group's UAP      January 1999


  Most UAP clients have no local state and are configured when booted
  through DHCP.  No existing DHCP option [6] has a data field that
  contains a URL.  Option 72 contains a list of IP addresses for WWW
  servers, but it is not adequate since a port and/or path can not be
  specified.  Hence there is a need for an option that contains a list
  of URLs.

User Authentication Protocol Option

  This option specifies a list of URLs, each pointing to a user
  authentication service that is capable of processing authentication
  requests encapsulated in the User Authentication Protocol (UAP).  UAP
  servers can accept either HTTP 1.1 or SSLv3 connections.  If the list
  includes a URL that does not contain a port component, the normal
  default port is assumed (i.e., port 80 for http and port 443 for
  https).  If the list includes a URL that does not contain a path
  component, the path /uap is assumed.

  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
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  |     Code      |    Length     |   URL list
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     Code            98

     Length          The length of the data field (i.e., URL list) in
                     bytes.

     URL list        A list of one or more URLs separated by the ASCII
                     space character (0x20).

References

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

  [2]  Technical Standard: Network Computing Client, The Open Group,
       Document Number C801, October 1998.

  [3]  Fielding, R., Gettys, J., Mogul, J., Frystyk, H., and T.
       Berners-Lee, "Hypertext Transfer Protocol -- HTTP/1.1", RFC
       2068, January 1997.

  [4]  Freier, A., Karlton, P., and P. Kocher, "The SSL Protocol,
       Version 3.0", Netscape Communications Corp., November 1996.
       Standards Information Base, The Open Group,
       http://www.db.opengroup.org/sib.htm#SSL_3.



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RFC 2485          DCHP Option for the Open Group's UAP      January 1999


  [5]  Berners-Lee, T., Masinter, L., and M. McCahill, "Uniform
       Resource Locators (URL)", RFC 1738, December 1994.

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

Security Considerations

  DHCP currently provides no authentication or security mechanisms.
  Potential exposures to attack are discussed in section 7 of the DHCP
  protocol specification.

  The User Authentication Protocol does not have a means to detect
  whether or not the client is communicating with a rogue
  authentication service that the client contacted because it received
  a forged or otherwise compromised UAP option from a DHCP service
  whose security was compromised.  Even secure authentication does not
  provide relief from this type of attack.  This security exposure is
  mitigated by the environmental assumptions documented in the Network
  Computing Client Technical Standard.

Author's Address

  Steve Drach
  Sun Microsystems, Inc.
  901 San Antonio Road
  Palo Alto, CA 94303

  Phone: (650) 960-1300
  EMail: [email protected]





















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RFC 2485          DCHP Option for the Open Group's UAP      January 1999


Full Copyright Statement

  Copyright (C) The Internet Society (1999).  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
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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
  MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
























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