Edit File: draft-joslin-config-schema-xx.txt
INTERNET-DRAFT M. Ansari draft-joslin-config-schema-10.txt Infoblox Category: Informational L. Howard Expires: September 2005 PADL Software Pty. Ltd. B. Neal-Joslin, Editor Hewlett-Packard Company 4 March, 2005 A Configuration Schema for LDAP Based Directory User Agents Status of this Memo Copyright (C) The Internet Society (2005). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 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 and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "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 IPR Statement By submitting this Internet-Draft, I certify that any applicable Neal-Joslin [Page 1] Internet-Draft DUA Configuration Schema March 2005 patent or other IPR claims of which I am aware have been disclosed, or will be disclosed, and any of which I become aware will be disclosed, in accordance with RFC 3668. The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf-ipr@ietf.org. Copies of IPR disclosures made to the IETF Secretariat and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr. Abstract This document describes a mechanism for distributed configuration of similar directory user agents. This document defines a schema for configuration of these DUAs that may be discovered using the Lightweight Directory Access Protocol in RFC 2251[1]. A set of attribute types and an objectclass are proposed, along with specific guidelines for interpreting them. A proposal of using attribute and objectclass mapping allows DUAs to re-configure their schema to that of the end user's environment. This document is intended to be a skeleton for future documents that describe configuration of specific DUA services. Neal-Joslin [Page 2] Internet-Draft DUA Configuration Schema March 2005 Table of Contents 1. Background & Motivation ...................................... 4 2. General Issues ............................................... 5 2.1 Terminology .................................................. 5 2.2 Attributes ................................................... 5 2.3 Object Classes ............................................... 6 2.4 Syntax Definitions ........................................... 6 3. Attribute Definitions ........................................ 6 4. Class Definition ............................................. 8 5. Implementation Details ....................................... 9 5.1.1 Interpreting the preferredServerList attribute ............. 9 5.1.2 Interpreting the defaultServerList attribute ............... 10 5.1.3 Interpreting the defaultSearchBase attribute ............... 11 5.1.4 Interpreting the authenticationMethod attribute ............ 12 5.1.5 Interpreting the credentialLevel attribute ................. 13 5.1.6 Interpreting the serviceSearchDescriptor attribute ......... 14 5.1.7 Interpreting the attributeMap attribute .................... 17 5.1.8 Interpreting the searchTimeLimit attribute ................. 20 5.1.9 Interpreting the bindTimeLimit attribute ................... 20 5.1.10 Interpreting the followReferrals attribute ................ 21 5.1.11 Interpreting the dereferenceAliases attribute ............. 21 5.1.12 Interpreting the profileTTL attribute ..................... 21 5.1.13 Interpreting the objectclassMap attribute ................. 22 5.1.14 Interpreting the defaultSearchScope attribute ............. 24 5.1.15 Interpreting the serviceAuthenticationMethod attribute .... 24 5.1.16 Interpreting the serviceCredentialLevel attribute ......... 25 5.2 Binding to the Directory Server .............................. 26 6. Security Considerations ...................................... 26 7. Acknowledgments .............................................. 27 8. References ................................................... 27 8.1 Normative References ......................................... 27 8.2 Informative References ....................................... 28 9. Examples ..................................................... 29 Neal-Joslin [Page 3] Internet-Draft DUA Configuration Schema March 2005 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 different 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 [2]. In developing these agents, we felt there are several issues that still need to be addressed to ease the deployment 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 [3]) containing similar attributes, but with different attribute names. This can lead to data redundancy 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 its 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 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 its successor. 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 Neal-Joslin [Page 4] Internet-Draft DUA Configuration Schema March 2005 auxiliary 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 Configuration 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 BCP 14 (RFC 2119) [4]. 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 serviceCredentialLevel serviceAuthenticationMethod attributeMap objectclassMap searchTimeLimit bindTimeLimit followReferrals dereferenceAliases profileTTL Neal-Joslin [Page 5] Internet-Draft DUA Configuration Schema March 2005 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 attributes defined in this document can be found section 5. keystring as defined by RFC 2252 [5] 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 [6] DistinguishedName as defined by RFC 2253 section 2 RelativeDistinguishedName as defined by RFC 2253 section 2 scope as defined by RFC 2255 [7] host as defined by RFC 3986 section 3.2.2 [8] hostport host [":" port ] port as defined by RFC 3986 section 3.2.3 [8] 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 addresses 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 ) Neal-Joslin [Page 6] Internet-Draft DUA Configuration Schema March 2005 ( 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 result' 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 methods 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 should re-read this configuration profile' EQUALITY integerMatch SYNTAX 1.3.6.1.4.1.1466.115.121.1.27 SINGLE-VALUE ) ( 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' Neal-Joslin [Page 7] Internet-Draft DUA Configuration Schema March 2005 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.1.14 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.1.15 NAME 'serviceAuthenticationMethod' DESC 'Identifies type of authentication method a DUA should use when binding to the LDAP server for a specific service' EQUALITY caseIgnoreMatch SYNTAX 1.3.6.1.4.1.1466.115.121.1.15 ) ( 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 ) 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 [9]. cn is used to represent the name of the DUA Neal-Joslin [Page 8] Internet-Draft DUA Configuration Schema March 2005 configuration 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 associated 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 (left to right) 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 remaining DSAs. The purpose of enumerating multiple DSAs is not for supplemental data, but for high availability of replicated data. This is also the main reason why an LDAP URL[10] syntax was not selected for this document. 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. Syntax: serverList = hostport *(space [hostport]) Neal-Joslin [Page 9] Internet-Draft DUA Configuration Schema March 2005 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 defaultServerList 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 attributes, credentialLevel, serviceCredentialLevel, bindTimeLimit, serviceAuthenticationMethod and authenticationMethod. Please review section 5.2 for details on how a DUA should properly bind to a DSA. Example: preferredServerList: 192.168.169.170 ldap1.mycorp.com ldap2:1389 [1080::8:800:200C:417A]:389 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 specified 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 contacts 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. Neal-Joslin [Page 10] Internet-Draft DUA Configuration Schema March 2005 Syntax: serverList = hostport *(space [hostport]) Default Value: If a defaultServerList attribute is not provided, the DUA MAY attempt to contact the same DSA that provided the configuration profile entry itself. The default DSA is contacted only if the preferredServerList attribute is also not provided. Other attribute notes: This attribute is used in conjunction with the preferredServerList 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 attributes, credentialLevel, serviceCredentialLevel, bindTimeLimit, serviceAuthenticationMethod and authenticationMethod. Please review section 5.2 for details on how a DUA should properly contact a DSA. Example: defaultServerList: 192.168.169.170 ldap1.mycorp.com ldap2:1389 [1080::8:800:200C:417A]:5912 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 [5] Default Value: There is no default value for the defaultSearchBase. A DUA MAY define its own method for determining the search base, if the defaultSearchBase is not provided. Neal-Joslin [Page 11] Internet-Draft DUA Configuration Schema March 2005 Other attribute notes: This attribute is used in conjunction with the 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[11]. 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 successful 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[12] 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 [13]). 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 [18] Note: Although multiple authentication methods may be specified in the syntax, at most one of each type is allowed. I.E. "simple;simple" is invalid. Default Value: If the authenticationMethod or serviceAuthenticationMethod Neal-Joslin [Page 12] Internet-Draft DUA Configuration Schema March 2005 (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 serviceAuthenticationMethod 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 (DSA and DUA) 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 [14]) 5.1.5 Interpreting the credentialLevel attribute Interpretation: The credentialLevel attribute defines what type(s) of credential(s) the DUA MUST 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 known identity, the DUA MUST attempt to bind to the DSA as that identity. The DUA should contain methods to determine the identity of the user such that that identity can be authenticated by the Neal-Joslin [Page 13] Internet-Draft DUA Configuration Schema March 2005 directory server using the defined authentication methods. 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 credential 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, authenticationMethod, 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- Neal-Joslin [Page 14] Internet-Draft DUA Configuration Schema March 2005 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[8], this draft requires the ability to supply multiple hosts as part of the configuration of the DSA. In addition, an ordered list of search descriptors 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 profile. 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 defaultSearchBase. 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 surrounded 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. If a DUA is performing a search for a particular service, Neal-Joslin [Page 15] Internet-Draft DUA Configuration Schema March 2005 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 serviceSearchDescriptor, the DUA SHOULD perform multiple search requests and in that case it MUST be in the order specified by the serviceSearchDescriptor. FYI: Service search descriptors do not exactly follow the LDAP URL syntax [7]. 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 DSA. 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 performing 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 [15]. 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 attributes in the filter have assumed to already have been mapped, or if it is expected that attribute mapping (see 5.1.7) 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 filter defined in the Neal-Joslin [Page 16] Internet-Draft DUA Configuration Schema March 2005 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 attributes of similar syntaxes as specified 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 original syntax and the new syntax. When DUAs do support attribute value translation, the list of capable translations SHOULD be documented in a description of the DUA service. Syntax: attributeMap = serviceID ":" origAttribute "=" attributes origAttribute = attribute Neal-Joslin [Page 17] Internet-Draft DUA Configuration Schema March 2005 attributes = wattribute *( space wattribute ) wattribute = whsp newAttribute whsp newAttribute = descr | "*NULL*" attribute = descr Values of the origAttribute are defined by and SHOULD be documented 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 following 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 constructed. 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 attribute OID. It SHOULD support attribute mapping based on the attribute name. 5) It is recommended that attribute mapping not be applied to Neal-Joslin [Page 18] Internet-Draft DUA Configuration Schema March 2005 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 target attribute MUST NOT be mapped to a third attribute. 7) A given attribute MUST only be mapped once for a given service. 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 "employeeName" 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 configuration profile entry as follows (represented in LDIF[16]): 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 generating 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 Neal-Joslin [Page 19] Internet-Draft DUA Configuration Schema March 2005 separate attributes in the directory. The email service may define that if the "mail" attribute is mapped to two different attributes, it will construct the email address as a concatenation 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 allow to perform a search request. Syntax: Defined by OID 1.3.6.1.4.1.1466.115.121.1.27. [5] 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: Neal-Joslin [Page 20] Internet-Draft DUA Configuration Schema March 2005 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 OID 1.3.6.1.4.1.1466.115.121.1.7. [5] 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 dereferencing. 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 Neal-Joslin [Page 21] Internet-Draft DUA Configuration Schema March 2005 Interpretation: The profileTTL attribute defines how often the DUA SHOULD re- load and reconfigure itself using the corresponding configuration 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 policy. Other attribute notes: If the profileTTL value is zero, the DUA SHOULD NOT automatically 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 attribute 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. Often, the objectclass attribute is used 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 service 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 Neal-Joslin [Page 22] Internet-Draft DUA Configuration Schema March 2005 defined for a particular service, it SHOULD 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 attributeMap 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 Service 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[17]. 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 Neal-Joslin [Page 23] Internet-Draft DUA Configuration Schema March 2005 objectclassMap attributes to the configuration profile entry as follows (represented in LDIF[16]): 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 contact 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 specified in the syntax, at most one of each type is allowed. Default Value: If the serviceAuthenticationMethod attribute is not provided, Neal-Joslin [Page 24] Internet-Draft DUA Configuration Schema March 2005 the authenticationMethod SHOULD be followed, or its default. 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 section 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, serviceAuthenticationMethod, authenticationMethod and bindTimeLimit. Please review section 5.2 for details on how to properly bind to a DSA. Example: Neal-Joslin [Page 25] Internet-Draft DUA Configuration Schema March 2005 serviceCredentialLevel: email:proxy anonymous 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 modification. Each service needs to consider implications of Neal-Joslin [Page 26] Internet-Draft DUA Configuration Schema March 2005 providing its service configuration as part of this profile and limit access to the profile entries accordingly. The management of the authentication credentials for the DUA is outside the scope of this document and needs to be handled by the DUA. Since the DUA needs to know how to properly bind to the directory server, the access control configuration of the DSA MUST assure that the DSA can view all the elements of the DUAConfigProfile attributes. For example, if the credentialLevel attribute contains "Self" but the DSA is unable to access the credentialLevel attribute, the DUA will instead attempt an anonymous connection to the directory server. The algorithm described by section 5.2 also has security considerations. Altering that design will alter the security aspects 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 8.1 Normative References [4] S. Bradner, "Key Words for use in RFCs to Indicate Requirement Levels", RFC 2119, March 1997. [5] M. Wahl, A. Coulbeck, T. Howes, S. Kille, "Lightweight Directory Access Protocol (v3): Attribute Syntax Definitions", RFC 2252, December 1997. [6] M. Wahl, S. Kille, T. Howes, "Lightweight Directory Access Protocol Neal-Joslin [Page 27] Internet-Draft DUA Configuration Schema March 2005 (v3): UTF-8 String Representation of Distinguished Names", RFC 2253, December 1997. [7] T. Howes, M. Smith, "The LDAP URL Format", RFC 2255, December 1997. [8] R. Hinden, B. Carpenter, L. Masinter, "Uniform Resource Identifier (URI): Generic Syntax", RFC 3986, January 2005. [9] M. Wahl, "A Summary of the X.500(96) User Schema for use with LDAPv3", RFC 2256, December 1997. [11] M. Wahl, H. Alvestrand, J. Hodges, R. Morgan, "Authentication Methods for LDAP", RFC 2828, May 2000 [13] J. Hodges, R. Morgan, M. Wahl, "Lightweight Directory Access Protocol [v3]: Extension for Transport Layer Security", RFC 2830, May 2000 [18] IANA, "SIMPLE AUTHENTICATION AND SECURITY LAYER (SASL) MECHANISMS", http://www.iana.org/assignments/sasl-mechanisms, April 2004 8.2 Informative References [1] M. Wahl, T. Howes, S. Kille, "Lightweight Directory Access Protocol (v3)", RFC 2251, December 1997. [2] L. Howard, "An Approach for Using LDAP as a Network Information Service", RFC 2307, March 1998. [3] Microsoft Corporation, "Windows Services for Unix 3.5", http://www.microsoft.com/windows/sfu/default.asp [12] J. Meyers, "Simple Authentication and Security Layer [SASL]", RFC 2222, October 1997 [14] P. Leach, C. Newman, "Using Digest Authentication as a SASL Neal-Joslin [Page 28] Internet-Draft DUA Configuration Schema March 2005 Mechanism", RFC 2831, May 2000 [15] T. Howes, "The String Representation of LDAP Search Filters", RFC 2254, December 1997. [16] G. Good, "The LDAP Data Interchange Format (LDIF) - Technical Specification", RFC 2849, June 2000. [17] M. Smith, "Definition of the inetOrgPerson LDAP Object Class", RFC 2789, April 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 colloquial name. This email service is defined by default to expect that users with email addresses will be of the "inetOrgPerson" objectclass type [17]. 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>)...) Neal-Joslin [Page 29] Internet-Draft DUA Configuration Schema March 2005 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 Hernandez." 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 <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 Neal-Joslin [Page 30] Internet-Draft DUA Configuration Schema March 2005 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)) Author's Addresses Luke Howard PADL Software Pty. Ltd. PO Box 59 Central Park Vic 3145 Australia EMail: lukeh@padl.com Bob Neal-Joslin Hewlett-Packard Company 19420 Homestead RD MS43-LF Cupertino, CA 95014 USA Phone: +1 408 447-3044 Neal-Joslin [Page 31] Internet-Draft DUA Configuration Schema March 2005 EMail: bob_joslin@hp.com Morteza Ansari Infoblox 475 Potrero Avenue Sunnyvale, CA 94085 USA Phone: +1 408-716-4300 EMail: morteza@infoblox.com Expires September 2005 Neal-Joslin [Page 32]
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