NETWORK WORKING GROUP                                        N. Williams
Internet-Draft                                                       Sun
Expires: December 30, 2004                                     July 2004



            GSS-API Domain-Based Service Names and Name Type
            draft-williams-gssapi-domain-based-names-00.txt


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   Copyright (C) The Internet Society (2004).  All Rights Reserved.


Abstract


   This document describes domainname-based service principal names and
   the corresponding name type for the GSS-API.


   Domain-based service names are similar to host-based service names,
   but using a domain name (not necessarily and Internat domain name)
   instead of or in addition to a hostname.  The primary purpose of
   domain-based service names is to provide a way to name clustered
   services after the domain which they service, thereby allowing their
   clients to authorize the service's servers based on authentication of
   their names.




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Table of Contents


   1. Conventions used in this document  . . . . . . . . . . . . . . . 3
   2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . 4
   3. Name Type OID and Symbolic Name  . . . . . . . . . . . . . . . . 5
   4. Query and Display Syntaxes . . . . . . . . . . . . . . . . . . . 6
   5. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
   6. Security Considerations  . . . . . . . . . . . . . . . . . . . . 8
   7. Normative  . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
      Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 8
      Intellectual Property and Copyright Statements . . . . . . . . . 9









































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1.  Conventions used in this document


   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 [RFC2119].















































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2.  Introduction


   The use of hostbased principal names for domain-wide services
   presents the problem of how to distinguish between an instance of a
   hostbased service that is authorized to respond for a domain and one
   that isn't.


   Consider LDAP.  LDAP with SASL and the Kerberos V GSS-API mechanism
   uses a hostbased principal with a service name of "ldap", a
   reasonable approach, provided there is only one logical LDAP
   directory in a Kerberos realm's domain, and that all ldap servers in
   that realm serve that one LDAP directory.  If there were other LDAP
   directories, then clients could not tell which service is authorized
   to serve which directory, not without assuming a secure method for
   finding LDAP servers (e.g., DNSSEC).  This is a significant, and
   oft-unstated restriction on users of LDAP.


   Domain based names can eliminate this problem by allowing LDAP
   service names to indicate which LDAP directory they are authorized to
   serve.


   A domain-based name consists of three required elements:
   o  a service name
   o  a domain name
   o  a hostname



























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3.  Name Type OID and Symbolic Name


   The new name type has an OID of
      [NOTE:  OID assignment to be made with IANA.]


      {iso(1) org(3) dod(6) internet(1) security(5) nametypes(6)
      gss-domain-based(5)}


   The recommended symbolic name for this GSS-API name type is
   "GSS_C_NT_DOMAINBASED_SERVICE".










































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4.  Query and Display Syntaxes


   There is a single syntax that applies to both query and display forms
   of domain-based names.  (We ignore string profile matters here as the
   GSS-API's, and its mechanisms' use of character strings are out of
   scope for this document.)


   The syntax is:
      domain-based-name :=
         | <service> '@' <domain> '@' <hostname>
         | <service> '@@' <hostname>


   The domain name element is only optional in the query syntax of
   domain-based names.


   A missing domain name is always to be added by the GSS-API mechanisms
   during name canonicalization, using whatever default values are
   appropriate for the mechanisms.


   Therefore the display form of domain-based MNs (see [RFC2743]) MUST
   include all three elements of domain-based names.


   Note that for Internet domain names the trailing '.' is not and MUST
   NOT be included in the domain name (or hostname) parts of the display
   form GSS-API domain-based MNs.



























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5.  Examples


   o  ldap@@ds1.example.tld
   o  ldap@example.tld@ds1.example.tld


   o  kadmin@@kdc1.example.tld
   o  kadmin@example.tld@kdc1.example.tld













































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6.  Security Considerations


   Use of GSS-API domain-based names may not be negotiable by some
   GSS-API mechanisms, and some acceptors may not support GSS-API
   domain-based names.  In such cases initiators are left to fallback on
   the use of hostbased names, in which case the initiators MUST also
   verify that the acceptor's hostbased name is authorized to provide
   the given service for the domain that the initiator had wanted.


   The above security consideration also applies to all GSS-API
   initiators who lack support for domain-based service names.


7  Normative


   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.


   [RFC2743]  Linn, J., "Generic Security Service Application Program
              Interface Version 2, Update 1", RFC 2743, January 2000.


   [RFC2744]  Wray, J., "Generic Security Service API Version 2 :
              C-bindings", RFC 2744, January 2000.



Author's Address


   Nicolas Williams
   Sun Microsystems
   5300 Riata Trace Ct
   Austin, TX  78727
   US


   EMail: Nicolas.Williams@sun.com



















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Acknowledgment


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   Internet Society.




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