


Application Working Group                                      M. Ansari
INTERNET-DRAFT                                    Sun Microsystems, Inc.
Expires Febuary 2003                                           L. Howard
                                                 PADL Software Pty. Ltd.
                                                         B. Joslin [ed.]
                                                 Hewlett-Packard Company

                                                    September 15th, 2003
Intended Category: Informational


                 A Configuration Schema for LDAP Based
                         Directory User Agents
                  <draft-joslin-config-schema-07.txt>


Status of this Memo

     This memo provides information for the Internet community.  This
     memo does not specify an Internet standard of any kind.  Distribu-
     tion of this memo is unlimited.

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

     This document is an Internet-Draft. Internet-Drafts are working
     documents of the Internet Engineering Task Force (IETF), its areas,
     and its working groups. Note that other groups may also distribute
     working documents as Internet-Drafts.

     Internet-Drafts are draft documents valid for a maximum of six
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     To learn the current status of any Internet-Draft, please check the
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     Rim).

     Distribution of this document is unlimited.

Abstract

     This document describes a mechanism for global configuration of
     similar directory user agents.  This document defines a schema for



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     configuration of these DUAs that may be discovered using the Light-
     weight Directory Access Protocol in RFC 2251[17].  A set of attri-
     bute types and an objectclass are proposed, along with specific
     guidelines for interpreting them.  A significant feature of the
     global configuration policy for DUAs is a mechanism that allows
     DUAs to re-configure their schema to that of the end user's
     environment.  This configuration is achieved through attribute and
     objectclass mapping.  This document is intended to be a skeleton
     for future documents that describe configuration of specific DUA
     services.


1.  Background & Motivation

     The LDAP protocol has brought about a new and nearly ubiquitous
     acceptance of the directory server.  Many new client applications
     (DUAs) are being created that use LDAP directories for many dif-
     ferent services.  And although the LDAP protocol has eased the
     development of these applications, some challenges still exist for
     both developers and directory administrators.

     The authors of this document are implementers of DUAs described by
     RFC 2307 [14].  In developing these agents, we felt there are
     several issues that still need to be addressed to ease the deploy-
     ment and configuration of a large network of these DUAs.

     One of these challenges stems from the lack of a utopian schema.  A
     utopian schema would be one that every application developer could
     agree upon and that would support every application.  Unfortunately
     today, many DUAs define their own schema (like RFC 2307 vs.
     Microsoft's Services for Unix [13]) containing similar attributes,
     but with different attribute names.  This can lead to data redun-
     dancy within directory entries and give directory administrators
     unwanted challenges, updating schemas and synchronizing data.

     So, one goal of this document is to eliminate data redundancy by
     having DUAs configure themselves to the schema of the deployed
     directory, instead of forcing it's own schema on the directory.

     Another goal of this document is to provide the DUA with enough
     configuration information so that it can discover how to retrieve
     its data in the directory, such as what locations to search in the
     directory tree.

     Finally, this document intends to describe a configuration method
     for DUAs that can be shared among many DUAs, on various platforms,
     providing as such, a configuration profile, the purpose is to cen-
     tralize and simplify management of DUAs.



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     This document is intended to provide the skeleton framework for
     future drafts, which will describe the individual implementation
     details for the particular services provided by that DUA.  The
     authors of this document plan to develop such a document for the
     Network Information Service DUA, described by RFC 2307 or its suc-
     cessor.

     We expect that as DUAs take advantage of this configuration scheme,
     each DUA will require additional configuration parameters, not
     specified by this document.  Thus, we would expect that new auxili-
     ary object classes, containing new configuration attributes will be
     created, and then joined with the structural class defined by this
     document to create a configuration profile for a particular DUA
     service.  And that by joining various auxiliary objectclasses for
     different DUA services, that configuration of various DUA services
     can be controlled by a single configuration profile entry.


2.  General Issues

     The schema defined by this document is defined under the "DUA Con-
     figuration Schema."  This schema is derived from the OID: iso (1)
     org (3) dod (6) internet (1) private (4) enterprises (1) Hewlett-
     Packard Company (11) directory (1) LDAP-UX Integration Project (3)
     DUA Configuration Schema (1).  This OID is represented in this
     document by the keystring "DUAConfSchemaOID"
     (1.3.6.1.4.1.11.1.3.1).

2.1 Terminology

     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 [15].

2.2 Attributes

     The attributes and classes defined in this document are summarized
     below.

     The following attributes are defined in this document:

          preferredServerList
          defaultServerList
          defaultSearchBase
          defaultSearchScope
          authenticationMethod
          credentialLevel
          serviceSearchDescriptor



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          serviceCredentialLevel
          serviceAuthenticationMethod
          attributeMap
          objectclassMap
          searchTimeLimit
          bindTimeLimit
          followReferrals
          dereferenceAliases
          profileTTL

2.3 Object Classes

     The following object class is defined in this document:

          DUAConfigProfile

2.4 Syntax Definitions

     The following syntax definitions are used throughout this document.
     This document does not define new syntaxes that must be supported
     by the directory server.  The string encoding used by the attri-
     butes defined in this document can be found section 5.

          keystring                 as defined by RFC 2252 [2]
          descr                     as defined by RFC 2252 section 4.1
          a                         as defined by RFC 2252 section 4.1
          d                         as defined by RFC 2252 section 4.1
          space                     as defined by RFC 2252 section 4.1
          whsp                      as defined by RFC 2252 section 4.1
          base                      as defined by RFC 2253 [3]
          DistinguishedName         as defined by RFC 2253 section 2
          RelativeDistinguishedName as defined by RFC 2253 section 2
          scope                     as defined by RFC 2255 [5]
          IPv4address               as defined by RFC 2396 [9]
          hostport                  as defined by RFC 2396 section 3.2.2
          port                      as defined by RFC 2396 section 3.2.2
          ipv6reference             as defined by RFC 2732 [10]
          host                      as defined by RFC 2732 section 3
          serviceID                 = keystring


3.  Attribute Definitions

     This section contains attribute definitions to be used by DUAs when
     discovering their configuration.

          ( DUAConfSchemaOID.1.0 NAME 'defaultServerList'
            DESC 'Default LDAP server host address used by a DUA'



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            EQUALITY caseIgnoreMatch
            SYNTAX 1.3.6.1.4.1.1466.115.121.1.15
            SINGLE-VALUE )

          ( DUAConfSchemaOID.1.1 NAME 'defaultSearchBase'
            DESC 'Default LDAP base DN used by a DUA'
            EQUALITY distinguishedNameMatch
            SYNTAX 1.3.6.1.4.1.1466.115.121.1.12
            SINGLE-VALUE )

          ( DUAConfSchemaOID.1.2 NAME 'preferredServerList'
            DESC 'Preferred LDAP server host addresses to be used by a
            DUA'
            EQUALITY caseIgnoreMatch
            SYNTAX 1.3.6.1.4.1.1466.115.121.1.15
            SINGLE-VALUE )

          ( DUAConfSchemaOID.1.3 NAME 'searchTimeLimit'
            DESC 'Maximum time in seconds a DUA should allow for a
            search to complete'
            EQUALITY integerMatch
            SYNTAX 1.3.6.1.4.1.1466.115.121.1.27
            SINGLE-VALUE )

          ( DUAConfSchemaOID.1.4 NAME 'bindTimeLimit'
            DESC 'Maximum time in seconds a DUA should allow for the
            bind operation to complete'
            EQUALITY integerMatch
            SYNTAX 1.3.6.1.4.1.1466.115.121.1.27
            SINGLE-VALUE )

          ( DUAConfSchemaOID.1.5 NAME 'followReferrals'
            DESC 'Tells DUA if it should follow referrals
            returned by a DSA search result'
            EQUALITY booleanMatch
            SYNTAX 1.3.6.1.4.1.1466.115.121.1.7
            SINGLE-VALUE )

          ( DUAConfSchemaOID.1.16 NAME 'dereferenceAliases'
            DESC 'Tells DUA if it should dereference aliases'
            EQUALITY booleanMatch
            SYNTAX 1.3.6.1.4.1.1466.115.121.1.7
            SINGLE-VALUE )

          ( DUAConfSchemaOID.1.6 NAME 'authenticationMethod'
            DESC 'A keystring which identifies the type of
            authentication method used to contact the DSA'
            EQUALITY caseIgnoreMatch



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            SYNTAX 1.3.6.1.4.1.1466.115.121.1.15
            SINGLE-VALUE )

          ( DUAConfSchemaOID.1.7 NAME 'profileTTL'
            DESC 'Time to live, in seconds, before a client DUA
            should re-read this configuration profile'
            EQUALITY integerMatch
            SYNTAX 1.3.6.1.4.1.1466.115.121.1.27
            SINGLE-VALUE )

          ( DUAConfSchemaOID.1.14 NAME 'serviceSearchDescriptor'
            DESC 'LDAP search descriptor list used by a DUA'
            EQUALITY caseExactMatch
            SYNTAX 1.3.6.1.4.1.1466.115.121.1.15 )

          ( DUAConfSchemaOID.1.9 NAME 'attributeMap'
            DESC 'Attribute mappings used by a DUA'
            EQUALITY caseIgnoreIA5Match
            SYNTAX 1.3.6.1.4.1.1466.115.121.1.26 )

          ( DUAConfSchemaOID.1.10 NAME 'credentialLevel'
            DESC 'Identifies type of credentials a DUA should
            use when binding to the LDAP server'
            EQUALITY caseIgnoreIA5Match
            SYNTAX 1.3.6.1.4.1.1466.115.121.1.26
            SINGLE-VALUE )

          ( DUAConfSchemaOID.1.11 NAME 'objectclassMap'
            DESC 'Objectclass mappings used by a DUA'
            EQUALITY caseIgnoreIA5Match
            SYNTAX 1.3.6.1.4.1.1466.115.121.1.26 )

          ( DUAConfSchemaOID.1.12 NAME 'defaultSearchScope'
            DESC 'Default search scope used by a DUA'
            EQUALITY caseIgnoreIA5Match
            SYNTAX 1.3.6.1.4.1.1466.115.121.1.26
            SINGLE-VALUE )

          ( DUAConfSchemaOID.1.13 NAME 'serviceCredentialLevel'
            DESC 'Identifies type of credentials a DUA
            should use when binding to the LDAP server for a
            specific service'
            EQUALITY caseIgnoreIA5Match
            SYNTAX 1.3.6.1.4.1.1466.115.121.1.26 )

          ( DUAConfSchemaOID.1.15 NAME 'serviceAuthenticationMethod'
            DESC 'Authentication method used by a service of the DUA'
            EQUALITY caseIgnoreMatch



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            SYNTAX 1.3.6.1.4.1.1466.115.121.1.15 )


4.  Class Definition

     The objectclass below is constructed from the attributes defined in
     3, with the exception of the cn attribute, which is defined in RFC
     2256 [8].  cn is used to represent the name of the DUA configura-
     tion profile.

        ( DUAConfSchemaOID.2.5 NAME 'DUAConfigProfile'
          SUP top STRUCTURAL
          DESC 'Abstraction of a base configuration for a DUA'
          MUST ( cn )
          MAY ( defaultServerList $ preferredServerList $
                defaultSearchBase $ defaultSearchScope $
                searchTimeLimit $ bindTimeLimit $
                credentialLevel $ authenticationMethod $
                followReferrals $ dereferenceAliases $
                serviceSearchDescriptor $ serviceCredentialLevel $
                serviceAuthenticationMethod $ objectclassMap $
                attributeMap $ profileTTL ) )


5.  Implementation Details

5.1.1 Interpreting the preferredServerList attribute

     Interpretation:

          As described by the syntax, the preferredServerList parameter
          is a white-space separated list of server addresses and asso-
          ciated port numbers.  When the DUA needs to contact a DSA, the
          DUA MUST first attempt to contact one of the servers listed in
          the preferredServerList attribute.  The DUA MUST contact the
          DSA specified by the first server address in the list.  If
          that DSA is unavailable, the remaining DSAs MUST be queried in
          the order provided until a connection is established with a
          DSA.  Once a connection with a DSA is established, the DUA
          SHOULD NOT attempt to establish a connection with the remain-
          ing DSAs.

          If the DUA is unable to contact any of the DSAs specified by
          the preferredServerList, the defaultServerList attribute MUST
          be examined, as described in 5.1.2.  The servers identified by
          the preferredServerList MUST be contacted before attempting to
          contact any of the servers specified by the defaultServerList.




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     Syntax:

          serverList       = host *(space [host])

     Default Value:

          The preferredServerList attribute does not have a default
          value.  Instead a DUA MUST examine the defaultServerList
          attribute.

     Other attribute notes:

          This attribute is used in conjunction with the defaultServer-
          List attribute.  Please see section 5.1.2 for additional
          implementation notes.  Determining how the DUA should query
          the DSAs also depends on the additional configuration attri-
          butes, credentialLevel, serviceCredentialLevel, bindTimeLimit,
          serviceAuthenticationMethod and authenticationMethod.  Please
          review section 5.2 for details on how a Posix DUA should prop-
          erly bind to a DSA.

     Example:

          preferredServerList: 1.2.3.4 ldap1.mycorp.com ldap2:1389
            [1080::8:800:200C:417A]:1389

5.1.2 Interpreting the defaultServerList attribute

     Interpretation:

          The defaultServerList attribute MUST only be examined if the
          preferredServerList attribute is not provided, or the DUA is
          unable to establish a connection with one of the DSAs speci-
          fied by the preferredServerList.

          If more than one address is provided, the DUA may choose to
          either accept the order provided, or choose to create its own
          order, based on what the DUA determines is the "best" order of
          servers to query.  For example, the DUA may choose to examine
          the server list and choose to query the DSAs in order based on
          the "closest" server or the server with the least amount of
          "load." Interpretation of the "best" server order is entirely
          up to the DUA, and not part of this document.

          Once the order of server addresses is determined, the DUA con-
          tacts the DSA specified by the first server address in the
          list.  If that DSA is unavailable, the remaining DSAs SHOULD
          be queried until an available DSA is found or no more DSAs are



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          available.  If a server address or port is invalid, the DUA
          SHOULD proceed to the next server address as described just
          above.

     Syntax:

          serverList       = host *(space [host])

     Default Value:

          If a defaultServerList attribute is not provided, the DUA
          should xxx attempt to contact the same DSA that provided the
          configuration profile entry itself.  The default DSA is con-
          tacted only if the preferredServerList attribute is also not
          provided.

     Other attribute notes:

          This attribute is used in conjunction with the preferredSer-
          verList attribute.  Please see section 5.1.1 for additional
          implementation notes.  Determining how the DUA should query
          the DSAs also depends on the additional configuration attri-
          butes, credentialLevel, serviceCredentialLevel, bindTimeLimit,
          serviceAuthenticationMethod and authenticationMethod.  Please
          review section 5.2 for details on how a DUA should properly
          contact a DSA.

     Example:

          defaultServerList: 1.2.3.4 ldap1.mycorp.com ldap2:1389
            [1080::8:800:200C:417A]:1389

5.1.3 Interpreting the defaultSearchBase attribute

     Interpretation:

          When a DUA needs to search the DSA for information, this
          attribute provides the "base" for the search.  This parameter
          can be overridden or appended by the serviceSearchDescriptor
          attribute.  See section 5.1.6.

     Syntax:

          Defined by OID 1.3.6.1.4.1.1466.115.121.1.12

     Default Value:

          There is no default value for the defaultSearchBase.  A DUA



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          MAY define its own method for determining the search base, if
          the defaultSearchBase is not provided.

     Other attribute notes:

          This attribute is used in conjunction with the serviceSear-
          chDescriptor attribute.  See section 5.1.6.

     Example:

          defaultSearchBase: dc=mycompany,dc=com

5.1.4 Interpreting the authenticationMethod attribute

     Interpretation:

          The authenticationMethod attribute defines an ordered list of
          LDAP bind methods to be used when attempting to contact a
          DSA[1].   The serviceAuthenticationMethod overrides this value
          for a particular service (see 5.1.15.)  Each method MUST be
          attempted in the order provided by the attribute, until a suc-
          cessful LDAP bind is performed ("none" is assumed to always be
          successful.) However the DUA MAY skip over one or more
          methods.  See section 5.2 for more information.

            none   - The DUA does not perform an LDAP bind.
            simple - The DUA performs an LDAP simple bind.
            sasl   - The DUA performs an LDAP SASL bind using the
                     specified SASL mechanism and options.
            tls    - The DUA performs an LDAP StartTLS operation
                     followed by the specified bind method (for more
                     information refer to section 5.1 of RFC 2830 [12]).

     Syntax:

          authMethod      = method *(";" method)
          method          = none | simple | sasl | tls
          none            = "none"
          simple          = "simple"
          sasl            = "sasl/" saslmech [ ":" sasloption ]
          sasloption      = "auth-conf" | "auth-int"
          tls             = "tls:" (none | simple | sasl)
          saslmech        = SASL mechanism name as defined in
                            RFC 2222[7], section 3

          Note: Although multiple authentication methods may be speci-
          fied in the syntax, at most one of each type is allowed.




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     Default Value:

          If the authenticationMethod or serviceAuthenticationMethod
          (for that particular service) attributes are not provided, the
          DUA MAY choose to bind to the DSA using any method defined by
          the DUA.  However, if either authenticationMethod or servi-
          ceAuthenticationMethod are provided, the DUA MUST only use the
          methods specified.

     Other attribute notes:

          When using TLS, the string "tls:sasl/EXTERNAL" implies that
          two way authentication is to be performed.  Any other TLS
          authentication method implies one way (DSA side credential)
          authentication.

          Determining how the DUA should bind to the DSAs also depends
          on the additional configuration attributes, credentialLevel,
          serviceCredentialLevel, serviceAuthenticationMethod and
          bindTimeLimit.  Please review section 5.2 for details on how
          to properly bind to a DSA.

     Example:

          authenticationMethod: tls:simple;sasl/DIGEST-MD5
          (see [11])

5.1.5 Interpreting the credentialLevel attribute

     Interpretation:

          The credentialLevel attribute defines what type(s) of
          credential(s) the DUA SHOULD use when contacting the DSA.  The
          serviceCredentialLevel overrides this value for a particular
          service (5.1.16.)  The credentialLevel can contain more than
          one credential type, separated by white space.

          anonymous - The DUA SHOULD NOT use a credential when binding
          to the DSA.

          proxy - The DUA SHOULD use a known proxy identity when binding
          to the DSA.  A proxy identity is a specific credential that
          was created to represent the DUA.  This document does not
          define how the proxy user should be created, or how the DUA
          should determine what the proxy user's credential is.  This
          functionality is up to each implementation.

          self - When the DUA is acting on behalf of a "real user" the



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          DUA SHOULD attempt to bind to the DSA as that user.  The DUA
          SHOULD map the user's identity to a credential used in the
          directory.

          If the credentialLevel contains more than one credential type,
          the DUA MUST use the credential types in the order specified.
          However, the DUA MAY skip over one or more credential types.
          As soon as the DUA is able to successfully bind to the DSA,
          the DUA SHOULD NOT attempt to bind using the remaining creden-
          tial types.

     Syntax:

          credentialLevel   = level *(space level)
          level             = self | proxy | anonymous
          self              = "self"
          proxy             = "proxy"
          anonymous         = "anonymous"

          Note: Although multiple credential levels may be specified in
          the syntax, at most one of each type is allowed.  Refer to
          implementation notes in section 5.2 for additional syntax
          requirements for the credentialLevel attribute.

     Default Value:

          If the credentialLevel attribute is not defined, the DUA
          SHOULD NOT use a credential when binding to the DSA (also
          known as anonymous.)

     Other attribute notes:

          Determining how the DUA should bind to the DSAs also depends
          on the additional configuration attributes, authentication-
          Method, serviceAuthenticationMethod, serviceCredentialLevel
          and bindTimeLimit.  Please review section 5.2 for details on
          how to properly bind to a DSA.

     Example:

          credentialLevel: proxy anonymous

5.1.6 Interpreting the serviceSearchDescriptor attribute

     Interpretation:

          The serviceSearchDescriptor attribute defines how and where a
          DUA SHOULD search for information for a particular service.



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          The serviceSearchDescriptor contains a serviceID, followed by
          one or more base-scope-filter triples.  These base-scope-
          filter triples are used to define searches only for the
          specific service.  Multiple base-scope-filters allow the DUA
          to search for data in multiple locations of the DIT.  Although
          this syntax is very similar to the LDAP URL[6], this draft
          requires the ability to supply multiple hosts as part of the
          configuration of the DSA.  In addition, an ordered list of
          search descritors is required, which can not be specified by
          the LDAP URL.

          In addition to the triples, serviceSearchDescriptor might also
          contain the DN of an entry that will contain an alternate pro-
          file.  The DSA SHOULD re-evaluate the alternate profile and
          perform searches as specified by that profile.

          If the base, as defined in the serviceSearchDescriptor, is
          followed by the "," (ASCII 0x2C) character, this base is known
          as a relative base.  This relative base may be constructed of
          one or more RDN components.  The DUA MUST define the search
          base by appending the relative base with the defaultSear-
          chBase.

     Syntax:

          serviceSearchList = serviceID ":" serviceSearchDesc
                              *(";" serviceSearchDesc)
          serviceSearchDesc = confReferral | searchDescriptor
          searchDescriptor  = [base] ["?" [scope] ["?" [filter]]]
          confReferral      = "ref:" DistinguishedName
          base              = DistinguishedName |
                              RelativeBaseName
          RelativeBaseName  = 1*(RelativeDistinguishedName ",")
          filter            = UTF-8 encoded string

          If the base or filter contains the ";" (ASCII 0x3B) "?" (ASCII
          0x3F) """ (ASCII 0x22) or "\" (ASCII 0x5C) characters, those
          characters MUST be escaped (preceded with the "\" character.)
          Alternately the DN may be surrounded by quotes (ASCII 0x22.)
          Refer to RFC 2253, section 4.  If the base or filter are sur-
          rounded by quotes, only the """ character needs to be escaped.
          Any character that is preceded by the "\" character, which
          does not need to be escaped results in both "\" character and
          the character itself.

          The usage and syntax of the filter string MUST be defined by
          the DUA service.  A suggested syntax would be that as defined
          by RFC 2254.



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          If a DUA is performing a search for a particular service,
          which has a serviceSearchDescriptor defined, the DUA MUST set
          the base, scope and filter as defined.  Each base-scope-filter
          triple represents a single LDAP search operation.  If multiple
          base-scope-filter triples are provided in the serviceSear-
          chDescriptor, the DUA SHOULD perform multiple search requests
          and in that case it MUST be in the order specified by the ser-
          viceSearchDescriptor.

          FYI: Service search descriptors do not exactly follow the LDAP
          URL syntax [5].  The reasoning for this difference is to
          separate the host name(s) from the filter.  This allows the
          DUA to have a more flexible solution in choosing its provider.

     Default Values:

          If a serviceSearchDescriptor, or an element their-of, is not
          defined for a particular service, the DUA SHOULD create the
          base, scope and filter as follows:

            base   - Same as the defaultSearchBase or as
                     defined by the DUA service.
            scope  - Same as the defaultSearchScope or as
                     defined by the DUA service.
            filter - Use defaults as defined by DUAs service.

          If the defaultSearchBase or defaultSearchScope are not
          defined, then the DUA service may use its own default.


     Other attribute notes:

          If a serviceSearchDescriptor exists for a given service, the
          service MUST use at least one base-scope-filter triple in per-
          forming searches.  It SHOULD perform multiple searches per
          service if multiple base-scope-filter triples are defined for
          that service.

          The details of how the "filter" is interpreted by each DUA's
          service is defined by that service.  This means the filter is
          NOT REQUIRED to be a legal LDAP filter [4].  Furthermore,
          determining how attribute and objectclass mapping affects that
          search filter MUST be defined by the service.  I.E. The DUA
          SHOULD specify if the filter has been assumed to already have
          been mapped, or if it is expected that mapping would be
          applied to the filter.  In general practice, implementation
          and usability suggests that attribute and objectclass mapping
          (sections 5.1.7 and 5.1.13) SHOULD NOT be applied to the



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          filter defined in the serviceSearchDescriptor.

          It is assumed the serviceID is unique to a given service
          within the scope of any DUA that might use the given profile.

     Example:

          defaultSearchBase: dc=mycompany,dc=com

          serviceSearchDescriptor: email:ou=people,ou=org1,?
           one;ou=contractor,?one;
           ref:cn=profile,dc=mycompany,dc=com

          In this example, the DUA MUST search in
          "ou=people,ou=org1,dc=mycompany,dc=com" first.  The DUA then
          SHOULD search in "ou=contractor,dc=mycompany,dc=com", and
          finally it SHOULD search other locations as specified in the
          profile described at "cn=profile,dc=mycompany,dc=com".  For
          more examples, see section 9.


5.1.7 Interpreting the attributeMap attribute

     Interpretation:

          A DUA SHOULD perform attribute mapping for all LDAP operations
          performed for a service that has an attributeMap entry.
          Because attribute mapping is specific to each service within
          the DUA, a "serviceID" is required as part of the attributeMap
          syntax.  I.E. not all DUA services should necessarily perform
          the same attribute mapping.

          Attribute mapping in general is expected be used to map attri-
          butes of similar syntaxes as specified by the service sup-
          ported by the DUA.  However, a DUA is NOT REQUIRED to verify
          syntaxes of mapped attributes.  If the DUA does discover that
          the syntax of the mapped attribute does not match that of the
          original attribute, the DUA MAY perform translation between
          the original syntax and the new syntax.  When DUAs do support
          attribute value translation, the list of capabable transla-
          tions SHOULD be documented in a description of the DUA ser-
          vice.

     Syntax:

          attributeMap      = serviceID ":" origAttribute "="
                              attributes
          origAttribute     = attribute



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          attributes        = wattribute *( space wattribute )
          wattribute        = whsp newAttribute whsp
          newAttribute      = descr | "*NULL*"
          attribute         = descr

          Values of the origAttribute are defined by and SHOULD be docu-
          mented for the DUA service, as a list of known supported
          attributes.

     Default Value:

          By default, attributes that are used by a DUA service are not
          mapped unless mapped by the attributeMap attributes.  The DUA
          MUST NOT map an attribute unless it is explicitly defined by
          an attributeMap attribute.

     Other attribute notes:

          When an attribute is mapped to the special keystring "*NULL*",
          the DUA SHOULD NOT request that attribute from the DSA, when
          performing a search or compare request.  If the DUA is also
          capable of performing modification on the DSA, the DUA SHOULD
          NOT attempt to modify any attribute which has been mapped to
          "*NULL*".

          It is assumed the serviceID is unique to a given service
          within the scope of the DSA.

          A DUA SHOULD support attribute mapping.  If it does, the fol-
          lowing additional rules apply:

          1) The list of attributes that are allowed to be mapped SHOULD
          defined by and documented for the service.

          2) Any supported translation of mapping from attributes of
          dissimilar syntax SHOULD also be defined and documented.

          3) If an attribute may be mapped to multiple attributes the
          DSA SHOULD define a syntax or usage statement for how the new
          attribute value will be evaluated.  Furthermore, the resulting
          translated syntax of the combined attributes MUST be the same
          as the attribute being mapped.

          4) A DUA MUST support mapping of attributes using the attri-
          bute OID.  It SHOULD support attribute mapping based on the
          attribute name.

          5) It is recommended that attribute mapping not be applied to



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          parents of the target entries.

          6) Attribute mapping is not recursive.  In other words, if an
          attribute has been mapped to a target attribute, that new tar-
          get attribute MUST NOT be mapped to a third attribute.

          7) A given attribute MUST only be mapped once for a given ser-
          vice.


     Example:

          Suppose a DUA is acting on behalf of an email service.  By
          default the "email" service uses the "mail", "cn" and "sn"
          attributes to discover mail addresses.  However, the email
          service has been deployed in an environment that uses "employ-
          eeName" instead of "cn."  And also instead of using the "mail"
          attribute for email addresses, the "email" attribute is used
          for that purpose.  In this case, the attribute "cn" can be
          mapped to "employeeName," allowing the DUA to perform searches
          using the "employeeName" attribute as part of the search
          filter, instead of "cn".  And "mail" can be mapped to "email"
          when attempting to retrieve the email address.  This mapping
          is performed by adding the attributeMap attributes to the con-
          figuration profile entry as follows (represented in LDIF[18]):

          attributeMap: email:cn=employeeName
          attributeMap: email:mail=email

          As described above, the DUA MAY also map a single attribute to
          multiple attributes.  When mapping a single attribute to more
          than one attribute, the new syntax or usage of the mapped
          attribute must be intrinsically defined by the DUAs service.

          attributeMap: email:cn=firstName lastName

          In the above example, the DUA creates the new value by gen-
          erating space separated string using the values of the mapped
          attributes.  In this case, a special mapping must be defined
          so that a proper search filter can be created.  For further
          information on this example, please refer to section 9.

          Another possibility for multiple attribute mapping might come
          in when constructing returned attributes.  For example,
          perhaps all email addresses are of a guaranteed syntax of
          "uid@domain".  And in this example, the uid and domain are
          separate attributes in the directory.  The email service may
          define that if the "mail" attribute is mapped to two different



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          attributes, it will construct the email address as a concate-
          nation of the uid and domain attributes, placing the "@" char-
          acter between them.

          attributeMap: email:mail=uid domain


5.1.8 Interpreting the searchTimeLimit attribute

     Interpretation:

          The searchTimeLimit attribute defines the maximum time, in
          seconds, that a DUA SHOULD allow to perform a search request.

     Syntax:

          Defined by OID 1.3.6.1.4.1.1466.115.121.1.27.

     Default Value:

          If the searchTimeLimit attribute is not defined or is zero,
          the search time limit is not enforced by the DUA.

     Other attribute notes:

          This time limit only includes the amount of time required to
          perform the LDAP search operation.  If other operations are
          required, those operations do not need to be considered part
          of the search time.  See bindTimeLimit for the LDAP bind
          operation.

5.1.9 Interpreting the bindTimeLimit attribute

     Interpretation:

          The bindTimeLimit attribute defines the maximum time, in
          seconds, that a DUA SHOULD allow to perform an LDAP bind
          request against each server on the preferredServerList or
          defaultServerList.

     Syntax:

          Defined by OID 1.3.6.1.4.1.1466.115.121.1.27.

     Default Value:

          If the bindTimeLimit attribute is not defined or is zero, the
          bind time limit is not enforced by the DUA.



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     Other attribute notes:

          This time limit only includes the amount of time required to
          perform the LDAP bind operation.  If other operations are
          required, those operations do not need to be considered part
          of the bind time.  See searchTimeLimit for the LDAP search
          operation.

5.1.10 Interpreting the followReferrals attribute

     Interpretation:

          If set to TRUE, the DUA SHOULD follow any referrals if
          discovered.

          If set to FALSE, the DUA MUST NOT follow referrals.

     Syntax:

          Defined by OID 1.3.6.1.4.1.1466.115.121.1.7.

     Default Value:

          If the followReferrals attribute is not set or set to an
          invalid value the default value is TRUE.

5.1.11 Interpreting the dereferenceAliases attribute

     Interpretation:

          If set to TRUE, the DUA SHOULD enable alias dereferening.

          If set to FALSE, the DUA MUST NOT enable alias dereferencing.

     Syntax:

          Defined by OID 1.3.6.1.4.1.1466.115.121.1.7.

     Default Value:

          If the dereferenceAliases attribute is not set or set to an
          invalid value the default value is TRUE.

5.1.12 Interpreting the profileTTL attribute

     Interpretation:

          The profileTTL attribute defines how often the DUA SHOULD re-



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          load and reconfigure itself using the corresponding configura-
          tion profile entry.  The value is represented in seconds.
          Once a DUA reloads the profile entry, it SHOULD re-configure
          itself with the new values.

     Syntax:

          Defined by OID 1.3.6.1.4.1.1466.115.121.1.27.

     Default Value:

          If not specified the DUA MAY use its own reconfiguration pol-
          icy.

     Other attribute notes:

          If the profileTTL value is zero, the DUA SHOULD NOT automati-
          cally re-load the configuration profile.

5.1.13 Interpreting the objectclassMap attribute

     Interpretation:

          A DUA MAY perform objectclass mapping for all LDAP operations
          performed for a service that has an objectclassMap entry.
          Because objectclass mapping is specific for each service
          within the DUA, a "serviceID" is required as part of the
          objectclassMap syntax.  I.E. Not all DUA services should
          necessarily perform the same objectclass mapping.

          Objectclass mapping SHOULD be used in conjunction with attri-
          bute mapping to map the required schema by the service to an
          equivalent schema that is available in the directory.

          Objectclass mapping may or may not be required by a DUA.  In
          general, the objectclass attribute is used primarily in search
          filters.  If a service search descriptor is provided, it is
          expected that the search filter contains a "correct" search
          filter (though this is not a requirement,) which does not need
          to be re-mapped.  However, when the service search descriptor
          is not provided, and the default search filter for that ser-
          vice contains the objectclass attribute, that search filter
          SHOULD be re-defined by objectclass mapping.  If a default
          search filter is not used, it SHOULD be re-defined through the
          serviceSearchDescriptor.  If a serviceSearchDescriptor is
          defined for a particular service, it SHOULD NOT be re-mapped
          by either the objectclassMap or attributeMap values.




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          One condition where the objectclassMap SHOULD be used is when
          the DUA is providing gateway functionality.  In this case, the
          DUA is acting on behalf of another service, which may pass in
          a search filter itself.  In this type of DUA, the DUA may
          alter the search filter according to the appropriate attribu-
          teMap and objectclassMap values.  And in this case, it is also
          assumed that a serviceSearchDescriptor is not defined.

     Syntax:

          objectclassMap    = serviceID ":" origObjectclass "="
                              objectclass
          origObjectclass   = objectclass
          objectclass       = keystring

          Values of the origObjectclass depend on the type of DUA Ser-
          vice using the objectclass mapping feature.

     Default Value:

          The DUA MUST NOT remap an objectclass unless it is explicitly
          defined by an objectclassMap attribute.

     Other attribute notes:

          A DUA SHOULD support objectclass mapping.  If it does, the DUA
          MUST support mapping of objectclasses using the objectclass
          OID.  It SHOULD support objectclass mapping based on the
          objectclass name.

          It is assumed the serviceID is unique to a given service
          within the scope of the DSA.

     Example:

          Suppose a DUA is acting on behalf of an email service.  By
          default the "email" service uses the "mail", "cn" and "sn"
          attributes to discover mail addresses in entries created using
          inetOrgPerson objectclass [16].  However, the email service
          has been deployed in an environment that uses entries created
          using "employee" objectclass.  In this case, the attribute
          "cn" can be mapped to "employeeName", and "inetOrgPerson" can
          be mapped to "employee", allowing the DUA to perform LDAP
          operations using the entries that exist in the directory.
          This mapping is performed by adding attributeMap and
          objectclassMap attributes to the configuration profile entry
          as follows (represented in LDIF[18]):




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          attributeMap: email:cn=employeeName
          objectclassMap: email:inetOrgPerson=employee


5.1.14 Interpreting the defaultSearchScope attribute

     Interpretation:

          When a DUA needs to search the DSA for information, this
          attribute provides the "scope" for the search.  This parameter
          can be overridden by the serviceSearchDescriptor attribute.
          See section 5.1.6.

     Syntax:

          scopeSyntax   = "base" | "one" | "sub"

     Default Value:

          The default value for the defaultSearchScope SHOULD be defined
          by the DUA service.  If the default search scope for a service
          is not defined then the scope SHOULD be for the DUA to perform
          a subtree search.


5.1.15 Interpreting the serviceAuthenticationMethod attribute

     Interpretation:

          The serviceAuthenticationMethod attribute defines an ordered
          list of LDAP bind methods to be used when attempting to con-
          tact a DSA for a particular service.  Interpretation and use
          of this attribute is the same as 5.1.4, but specific for each
          service.

     Syntax:

          svAuthMethod    = service ":" method *(";" method)

          Note: Although multiple authentication methods may be speci-
          fied in the syntax, at most one of each type is allowed.

     Default Value:

          If the serviceAuthenticationMethod attribute is not provided,
          the authenticationMethod SHOULD be followed, or its default.

     Other attribute notes:



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          Determining how the DUA should bind to the DSAs also depends
          on the additional configuration attributes, credentialLevel,
          serviceCredentialLevel and bindTimeLimit.  Please review sec-
          tion 5.2 for details on how to properly bind to a DSA.

     Example:

          serviceAuthenticationMethod: email:tls:simple;sasl/DIGEST-MD5


5.1.16 Interpreting the serviceCredentialLevel attribute

     Interpretation:

          The serviceCredentialLevel attribute defines what type(s) of
          credential(s) the DUA SHOULD use when contacting the DSA for a
          particular service.  Interpretation and used of this attribute
          are the same as 5.1.5.

     Syntax:

          svCredentialLevel = service ":" level *(space level)

          Refer to implementation notes in section 5.2 for additional
          syntax requirements for the credentialLevel attribute.

          Note: Although multiple credential levels may be specified in
          the syntax, at most one of each type is allowed.

     Default Value:

          If the serviceCredentialLevel attribute is not defined, the
          DUA MUST examine the credentialLevel attribute, or follow its
          default if not provided.

     Other attribute notes:

          Determining how the DUA should bind to the DSAs also depends
          on the additional configuration attributes, serviceAuthentica-
          tionMethod, authenticationMethod and bindTimeLimit.  Please
          review section 5.2 for details on how to properly bind to a
          DSA.

     Example:

          serviceCredentialLevel: email:proxy anonymous





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5.2 Binding to the Directory Server

     The DUA SHOULD use the following algorithm when binding to the
     server:

     for (clevel in credLevel) [see note 1]
       if (clevel is "anonymous")
         for (host in hostnames) [see note 2]
           if (server is responding)
             return success
         return failure
       else
         for (amethod in authMethod) [see note 3]
           if (amethod is none)
             for (host in hostnames)
               if (server is responding)
                 return success
             return failure
           else
             for (host in hostnames)
               authenticate using amethod and clevel
               if (authentication passed)
                 return success
     return failure

     Note 1: The credLevel is a list of credential levels as defined
             in serviceCredentialLevel (section 5.1.16) for a given
             service.  If the serviceCredentialLevel is not defined,
             the DUA MUST examine the credentialLevel attribute.

     Note 2: hostnames is the list of servers to contact as defined
             in 5.1.1 & 5.1.2.

     Note 3: The authMethod a list of authentication methods as defined
             in serviceAuthenticationMethod (section 5.1.15) for a
             given service.  If the serviceAuthenticationMethod is not
             defined, the DUA MUST examine the authenticationMethod
             attribute.



6.  Security Considerations

     The profile entries MUST be protected against unauthorized modifi-
     cation.  Since the profile is most useful if its content is avail-
     able broadly, it is recommended that the profile entries will be
     readable anonymously.  However, ultimately each service needs to
     consider implications of providing its service configuration as



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     part of this profile and limit access to the profile entries
     accordingly.  Additionally, the management of the authentication
     credentials for the DUA is outside the scope of this document and
     needs to be handled by the DUA.

     The algorithm described by section 5.2 also has security considera-
     tions.  Altering that design will alter the security aspectes of
     the configuration profile.


7.  Acknowledgments

     There were several additional authors of this document.  However we
     chose to represent only one author per company in the heading.
     From Sun we also would like to acknowledge Roberto Tam for his
     design work on Sun's first LDAP name service product and his input
     for this document.  From Hewlett-Packard we'd like to acknowledge
     Dave Binder for his work architecting Hewlett-Packard's LDAP name
     service product as well as his design guidance on this document.
     We'd also like to acknowledge Grace Lu from HP, for her input and
     implementation of HP's configuration profile manager code.


8.  References

[1]
     M. Wahl, H. Alvestrand, J. Hodges, R. Morgan, "Authentication
     Methods for LDAP", RFC 2828, May 2000

[2]
     M. Wahl, A. Coulbeck, T. Howes, S. Kille, "Lightweight Directory
     Access Protocol (v3): Attribute Syntax Definitions", RFC 2252,
     December 1997.

[3]
     M. Wahl, S. Kille, T. Howes, "Lightweight Directory Access Protocol
     (v3):  UTF-8 String Representation of Distinguished Names", RFC
     2253, December 1997.

[4]
     T. Howes, "The String Representation of LDAP Search Filters", RFC
     2254, December 1997.

[5]
     T. Howes, M. Smith, "The LDAP URL Format", RFC 2255, December 1997.

[6]
     T. Berners-Lee, L. Masinter, M. McCahill, "Uniform Resource



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     Locators (URL)", RFC 1738, December 1994.

[7]
     J. Meyers, "Simple Authentication and Security Layer [SASL]", RFC
     2222, October 1997

[8]
     M. Wahl, "A Summary of the X.500(96) User Schema for use with
     LDAPv3", RFC 2256, December 1997.

[9]
     T. Berners-Lee, R. Fielding, R. Fielding, "Uniform Resource Iden-
     tifiers (URI): Generic Syntax", RFC 2396, August 1998.

[10]
     R. Hinden, B. Carpenter, L. Masinter, "Format for Literal IPv6
     Addresses in URL's, RFC 2732, December 1999.

[11]
     P. Leach, C. Newman, "Using Digest Authentication as a SASL Mechan-
     ism", RFC 2831, May 2000

[12]
     J. Hodges, R. Morgan, M. Wahl, "Lightweight Directory Access Proto-
     col [v3]: Extension for Transport Layer Security", RFC 2830, May
     2000

[13]
     Microsoft Corporation, "Services for Unix 2.0",
     http://www.microsoft.com/WINDOWS2000/sfu/default.asp

[14]
     L. Howard, "An Approach for Using LDAP as a Network Information
     Service", RFC 2307, March 1998.

[15]
     S. Bradner, "Key Words for use in RFCs to Indicate Requirement Lev-
     els", RFC 2119, March 1997.

[16]
     M. Smith, "Definition of the inetOrgPerson LDAP Object Class", RFC
     2789, April 2000

[17]
     M. Wahl, T. Howes, S. Kille, "Lightweight Directory Access Protocol
     (v3)", RFC 2251, December 1997.

[18]



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     G. Good, "The LDAP Data Interchange Format (LDIF) - Technical
     Specification", RFC 2849, June 2000.


9.  Examples

     In this section we will describe a fictional DUA which provides one
     service, called the "email" service.  This service would be similar
     to an email client that uses an LDAP directory to discover email
     addresses based on a textual representation of the recipient's col-
     loquial name.

     This email service is defined by default to expect that users with
     email addresses will be of the "inetOrgPerson" objectclass type
     [16].  And by default, the "email" service expects the colloquial
     name to be stored in the "cn" attribute, while it expects the email
     address to be stored in the "mail" attribute (as one would expect
     as defined by the inetOrgPerson objectclass.)

     As a special feature, the "email" service will perform a special
     type of attribute mapping, when performing searches.  If the "cn"
     attribute has been mapped to two or more attributes, the "email"
     service will parse the requested search string and map each white-
     space separated token into the mapped attributes, respectively.

     The default search filter for the "email" service is
     "(objectclass=inetOrgPerson)".  The email service also defines that
     when it performs a name to address discovery, it will wrap the
     search filter inside a complex search filter as follows:

     (&(<filter>)(cn~=<name string>)

     or if "cn" has been mapped to multiple attributes, that wrapping
     would appear as follows:

     (&(<filter>)(attr1~=<token1>)(attr2~=<token2>)...)

     The below examples show how the "email" service builds it search
     requests, based on the defined profile.  In all cases, the
     defaultSearchBase is "o=airius.com" and the defaultSearchScope is
     undefined.

     In addition, for all examples, we assume that the "email" service
     has been requested to discover the email address for "Jane Hernan-
     dez."


     Example 1:



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     serviceSearchDescriptor: email:"ou=marketing,"

     base: ou=marketing,o=airius.com
     scope: sub
     filter: (&(objectclass=inetOrgPerson)(cn~=Jane Hernandez))

     Example 2:

     serviceSearchDescriptor: email:"ou=marketing,"?one?
      (&(objectclass=inetOrgPerson)(c=us))
     attributeMap: email:cn=2.5.4.42 sn

     Note: 2.5.4.42 is the OID that represents the "givenName"
     attribute.

     In this example, the email service performs <name string> parsing
     as described above to generate a complex search filter.  The above
     example results in one search.

     base: ou=marketing,o=airius.com
     scope: one
     filter: (&(&(objectclass=inetOrgPerson)(c=us))
                 (2.5.4.42~=Jane)(sn~=Hernandez))

     Example 3:

     serviceSearchDescriptor: email:ou=marketing,"?base
     attributeMap: email:cn=name

     This example is invalid, because either the quote should have been
     escaped, or there should have been a leading quote.

     Example 4:

     serviceSearchDescriptor: email:ou=\mar\\keting,\"?base
     attributeMap: email:cn=name

     base: ou=\mar\keting,"
     scope: base
     filter (&(objectclass=inetOrgPerson)(name~=Jane Hernandez))

     Example 5:

     serviceSearchDescriptor: email:ou="marketing",o=supercom

     This example is invalid, since the quote was not a leading quote,
     and thus should have been escaped.




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     Example 6:

     serviceSearchDescriptor: email:??(&(objectclass=person)
                                      (ou=Org1 \\(temporary\\)))

     base: o=airius.com
     scope: sub
     filter: (&((&(objectclass=person)(ou=Org1 \(Temporary\)))
               (cn~=Jane Henderson)))

     Example 7:

     serviceSearchDescriptor: email:"ou=funny?org,"

     base: ou=funny?org,o=airius.com
     scope: sub
     filter (&(objectclass=inetOrgPerson)(cn~=Jane Hernandez))


10.  Author's Addresses

     Luke Howard
     PADL Software Pty. Ltd.
     PO Box 59
     Central Park Vic 3145
     Australia

     EMail: lukeh@padl.com


     Bob Joslin
     Hewlett-Packard Company
     19420 Homestead RD  MS43-LF
     Cupertino, CA 95014
     USA

     Phone: +1 408 447-3044
     EMail: bob_joslin@hp.com


     Morteza Ansari
     Sun Microsystems, Inc.
     901 San Antonio RD  MS MPK17-203
     Palo Alto, CA 94303
     USA

     Phone: +1 650 786-6178
     EMail: morteza.ansari@sun.com



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