Application Working Group M. Ansari INTERNET-DRAFT Sun Microsystems, Inc. Expires December 2001 L. Howard PADL Software Pty. Ltd. B. Joslin [ed.] Hewlett-Packard Company July 19, 2001 Intended Category: Informational A Configuration Schema for LDAP Based Directory User Agents 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 months. Internet-Drafts may be updated, replaced, or made obsolete by other documents at any time. It is not appropriate to use Internet-Drafts as reference material or to cite them other than as a "working draft" or "work in progress". The list of current Internet-Drafts can be accessed at http://www.ietf.org/1id-abstracts.html The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. To learn the current status of any Internet-Draft, please check the 1id-abstracts.txt listing contained in the Internet-Drafts Shadow Directories on ds.internic.net (US East Coast), nic.nordu.net (Europe), ftp.isi.edu (US West Coast), or munnari.oz.au (Pacific Rim). Distribution of this document is unlimited. Abstract Joslin [Page 1] Internet-Draft DUA Configuration Schema November 2000 This document describes a mechanism for global configuration of similar directory user agents. This document proposes a schema for configuration of these DUAs that may be discovered using the Light- weight Directory Access Protocol [RFC2251]. A set of attribute types and an objectclass are proposed, along with specific guide- lines 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 implementors 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 being to Joslin [Page 2] Internet-Draft DUA Configuration Schema November 2000 centralize and simplify management of DUAs. 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 it's suc- cessor. We expect that as DUAs take advantage of this configuration scheme, each DUA will require additional configuration paramenters, 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 Joslin [Page 3] Internet-Draft DUA Configuration Schema November 2000 credentialLevel serviceSearchDescriptor serviceCredentialLevel serviceAuthenticationMethod attributeMap objectclassMap searchTimeLimit bindTimeLimit followReferrals 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 encodings 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' Joslin [Page 4] Internet-Draft DUA Configuration Schema November 2000 DESC 'Default LDAP server host address used by a DUA' 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 caseIgnoreIA5Match 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 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 Joslin [Page 5] Internet-Draft DUA Configuration Schema November 2000 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 SYNTAX 1.3.6.1.4.1.1466.115.121.1.15 ) 4. Class Definition Joslin [Page 6] Internet-Draft DUA Configuration Schema November 2000 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.2.4 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 $ 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 should contact the DSA specified by the first server address in the list. If that DSA is unavailable, the remaining DSAs should 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 should be examined, as described in 5.1.2. The servers iden- tified by the preferredServerList MUST be contacted before attempting to contact any of the servers specified by the defaultServerList. Syntax: serverList = host *(space [host]) Joslin [Page 7] Internet-Draft DUA Configuration Schema November 2000 Default Value: The preferredServerList attribute does not have a default value. Instead a DUA should 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 should contact 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 available. If a server address or port is invalid, the DUA should proceed to the next server address as described just above. Joslin [Page 8] Internet-Draft DUA Configuration Schema November 2000 Syntax: serverList = host *(space [host]) Default Value: If a defaultServerList attribute is not provided, the DUA should attempt to contact the same DSA which provided the con- figuration profile entry itself. The default DSA is contacted only if the preferredServerList attribute is also not pro- vided. 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 1.3.6.1.4.1.1466.115.121.1.12 Default Value: There is no default value for the defaultSearchBase. Other attribute notes: This attribute is used in conjunction with the Joslin [Page 9] Internet-Draft DUA Configuration Schema November 2000 serviceSearchDescriptor 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. The serviceAuthenticationAtrribute overrides this value for a particular service (see 5.1.14.) 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). 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 start_tls operation followed by the specified bind method (for more information refer to section 5.1 of RFC 2830). 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, section 3 Note: Although multiple authentication methods may be speci- fied in the syntax, at most one of each type is allowed. Default Value: If the authenticationMethod or serviceAutenticationMethod (for that particular service) attributes are not provided, the DUA may choose to bind to the DSA using any method. However, if either authenticationMethod or serviceAuthenticationMethod are provided, the DUA MUST only use the methods specified. Joslin [Page 10] Internet-Draft DUA Configuration Schema November 2000 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 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 (5.1.15.) 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 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 DUA contains more than one credential type, the DUA MUST use the credential types in the order specified. As soon as the DUA is able to successfully bind to the DSA, the DUA should not attempt to bind using the remaining credential types. If the DUA discovers that the credentials specified are invalid, it SHOULD NOT attempt further binds using any Joslin [Page 11] Internet-Draft DUA Configuration Schema November 2000 additional methods. Syntax: credentialLevel = level *(space level) level = self | proxy | anonymous self = "self" proxy = "proxy" anonymous = "anonymous" Note: Although multiple credentialLevels 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. 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. In addition to the triples, serviceSearchDescriptor might also contain the DN of an entry which will contain an alternate profile. The DSA SHOULD re-evaluate the alternate profile an Joslin [Page 12] Internet-Draft DUA Configuration Schema November 2000 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 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 filter string syntax can be more rigorously defined by the DUA service. A suggested syntax would be that as defined by RFC 2253. 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 tri- ples are provided, the DUA SHOULD perform the search requests in the order specified by the serviceSearchDescriptor. Default Values: If a serviceSearchDescriptor or an element there-of is not defined for a particular service, the DUA SHOULD create the base, scope and filter as follows: Joslin [Page 13] Internet-Draft DUA Configuration Schema November 2000 base - Same as the defaultSearchBase scope - Same as the defaultSearchScope filter - Use defaults as defined by DUAs service. If the defaultSearchBase is not defined, then the DUAs service may use its own default. Other attribute notes: If a serviceSearchDescriptor exists for a given service, the ser- vice MUST use at least one base-scope-filter triple in performing searches. It MAY 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 DUAs service is defined by each service. This means the filter is NOT REQUIRED to be a legal LDAP filter [4]. Furthermore, whether attribute map- ping or objectclass mapping applies to the filter or not should be defined by each service. It is assumed the serviceID is unique to a given service within the scope of the DSA. 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 sec- tion 5.1.7 Interpreting the attributeMap attribute Interpretation: A DUA SHOULD perform attribute mapping for all LDAP operations performed for a service which 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 Joslin [Page 14] Internet-Draft DUA Configuration Schema November 2000 the same attribute mapping. Attribute mapping SHOULD only be used to map attributes of similar syntaxes as required by the service supported 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 origi- nal syntax and the new syntax. Syntax: attributeMap = serviceId ":" origAttribute "=" attributes origAttribute = attribute attributes = wattribute *( space wattribute ) wattribute = whsp newAttribute whsp newAttribute = descr | "*NULL*" attribute = descr Values of the origAttribute depend on the type of application using the attribute mapping feature. 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 MUST 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 MUST 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) If an attribute may be mapped to multiple attributes the DSA MUST define a syntax or usage statement for how the new attribute value will be evaluated. Furthermore, the resulting Joslin [Page 15] Internet-Draft DUA Configuration Schema November 2000 syntax, through translation, of the combined attributes must be the same as the attribute being mapped. 2) A DUA MUST support mapping of attributes using the attri- bute OID. It SHOULD support attribute mapping based on the attribute name. 3) The naming attribute SHOULD NOT be mapped using one to many mapping. 4) Mapping should only be applied to the target entries being searched. Attribute mapping should not be applied to parents of the target entries. 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 retreive the email address. This mapping is performed by adding the attributeMap attributes to the con- figuration profile entry as follows (represented in [LDIF]): attributeMap: email:cn=employeeName attributeMap: email:mail=email DUAs 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 int- rinsically 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 futher information on this example, please refer to section 9. Another possibility for multiple attribute mapping might come in when constructing returned attributes. For example, Joslin [Page 16] Internet-Draft DUA Configuration Schema November 2000 perhaps all email addresses are of a guarenteed syntax of "uid@domain". And in this example, the uid and domain are attributes in the directory. The email service may define that if the "mail" attribute is mapped to two different attri- butes, it will construct the email address as a contactination of the uid and domain attributes, placing the "@" character 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 spend performing a search request request. Syntax: Defined by 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 timelimit 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 spend performing an LDAP bind request against each server on the preferredServerList or defaultServerList. Syntax: Defined by 1.3.6.1.4.1.1466.115.121.1.27. Joslin [Page 17] Internet-Draft DUA Configuration Schema November 2000 Default Value: If the bindTimeLimit attribute is not defined or is zero, the bind 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 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 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 profileTTL attribute Interpretation: The profileTTL attribute defines how often the DUA SHOULD re- load and reconfigure itself with using the corresponding con- figuration 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 1.3.6.1.4.1.1466.115.121.1.27. Default Value: If not specified the DUA MAY use its own reconfiguration Joslin [Page 18] Internet-Draft DUA Configuration Schema November 2000 policy. Other attribute notes: If the profileTTL value is zero, the DUA SHOULD NOT automati- cally re-load the configuration profile. 5.1.12 Interpreting the objectclassMap attribute Interpretation: A DUA MAY perform objectclass mapping for all LDAP operations performed for a service which has an objectclassMap entry. Because objectclass mapping is specific to 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, that does not need to be re-mapped. However, when the service search descriptor is not provided, and the default search filter for that service contains the objectclass attri- bute, that search filter may be re-defined by the objectclass mapping, if it applies to the default search filter. If a default search filter is not used, it SHOULD be re-defined through the serviceSearchDescriptor. If a serviceSear- chDescriptor is defined for a particular service, it MUST NOT be re-mapped by either the objectclassMap or attributeMap values. 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. Syntax: objectclassMap = serviceId ":" origObjectclass "=" Joslin [Page 19] Internet-Draft DUA Configuration Schema November 2000 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 which exist in the directory. This mapping is performed by adding attributeMap and objectclassMap attributes to the configuration profile entry as follows (represented in [LDIF]): attributeMap: email:cn=employeeName objectclassMap: email:inetorgperson=employee 5.1.13 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. Joslin [Page 20] Internet-Draft DUA Configuration Schema November 2000 See section 5.1.6. Syntax: scopeSyntax = "base" | "one" | "sub" Refer to implementation notes in section 5.2 for additional syntax requirements for the credentialLevel attribute. 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. 5.1.14 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 used 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, 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, credentialLevel, serviceCredentialLevel and bindTimeLimit. Please review sec- tion 5.2 for details on how to properly bind to a DSA. Example: Joslin [Page 21] Internet-Draft DUA Configuration Schema November 2000 authenticationMethod: email:tls:simple;sasl/DIGEST-MD5 5.1.15 Interpreting the serviceCredentialLevel attribute Interpretation: The serviceCrredentialLevel 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 credentialLevels 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 credentailLevel 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 5.2 Binding to the Directory Server The DUA SHOULD use the following algorithm when binding to the server: [EDITORS NOTE: this section likely to change] Joslin [Page 22] Internet-Draft DUA Configuration Schema November 2000 for (host in hostnames) [Note 1] for (clevel in credentialLevel) { if (clevel is anonymous) return success [Note 2] for (amethod in authMethod) { if (amethod is none) return success [Note 2] authenticate to host, using amethod and clevel if (authentication failed with bad credential) try next clevel if (authentication passed) return success } } Note 1: hostnames is the list of server to contact as defined in 5.1.1 & 5.1.2. Note 2: In case of anonymous or none, the DUA MAY try contacting the server to ensure the directory server is available and responding to requests. 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 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. 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. Joslin [Page 23] Internet-Draft DUA Configuration Schema November 2000 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 Loca- tors (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] Joslin [Page 24] Internet-Draft DUA Configuration Schema November 2000 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 [RFC2251] M. Wahl, T. Howes, S. Kille, "Lightweight Directory Access Protocol (v3)", RFC 2251, December 1997. [LDIF] 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- Joslin [Page 25] Internet-Draft DUA Configuration Schema November 2000 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: (&()(cn~=) or if "cn" has been mapped to multiple attributes, that wrapping would appear as follows: (&()(attr1~=)(attr2~=)...) 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: 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 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)) Joslin [Page 26] Internet-Draft DUA Configuration Schema November 2000 (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. 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 Joslin [Page 27] Internet-Draft DUA Configuration Schema November 2000 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 Joslin [Page 28]