DHCP Option for The Open Group's User Authentication Protocol
RFC 2485

Document Type RFC - Proposed Standard (January 1999; No errata)
Author Steve Drach 
Last updated 2013-03-02
Stream Internet Engineering Task Force (IETF)
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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.


   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].


   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

Drach                       Standards Track                     [Page 1]
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

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


   [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,

Drach                       Standards Track                     [Page 2]
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
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