 

Internet-Draft                                  Editor:  J. Sermersheim 
Intended Category: Standard Track                           Novell, Inc 
Document: draft-ietf-ldapbis-protocol-13.txt                   Mar 2003 
Obsoletes: RFC 2251                                                     
 
 
                            LDAP: The Protocol 
 
 
Status of this Memo 
 
   This document is an Internet-Draft and is in full conformance with 
   all provisions of Section 10 of RFC2026.  
    
   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/ietf/1id-abstracts.txt  
    
   The list of Internet-Draft Shadow Directories can be accessed at 
   http://www.ietf.org/shadow.html. 
    
   Distribution of this memo is unlimited. Technical discussion of this 
   document will take place on the IETF LDAP Revision Working Group 
   (LDAPbis) mailing list <ietf-ldapbis@openldap.org>. Please send 
   editorial comments directly to the editor <jimse@novell.com>. 
    
    
Abstract 
 
   This document describes the protocol elements, along with their 
   semantics and encodings, for the Lightweight Directory Access 
   Protocol (LDAP). LDAP provides access to distributed directory 
   services that act in accordance with X.500 data and service models. 
   These protocol elements are based on those described in the X.500 
   Directory Access Protocol (DAP). 
    
    
Table of Contents 
    
   1. Introduction.....................................................2 
   2. Conventions......................................................3 
   3. Protocol Model...................................................3 
   4. Elements of Protocol.............................................3 
   4.1. Common Elements................................................4 
   4.1.1. Message Envelope.............................................4 
   4.1.2. String Types.................................................6 
   4.1.3. Distinguished Name and Relative Distinguished Name...........6 
 
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   4.1.4. Attribute Descriptions.......................................6 
   4.1.5. Attribute Value..............................................7 
   4.1.6. Attribute Value Assertion....................................7 
   4.1.7. Attribute....................................................7 
   4.1.8. Matching Rule Identifier.....................................8 
   4.1.9. Result Message...............................................8 
   4.1.10. Referral...................................................10 
   4.1.11. Controls...................................................11 
   4.2. Bind Operation................................................12 
   4.3. Unbind Operation..............................................14 
   4.4. Unsolicited Notification......................................15 
   4.5. Search Operation..............................................16 
   4.6. Modify Operation..............................................23 
   4.7. Add Operation.................................................24 
   4.8. Delete Operation..............................................25 
   4.9. Modify DN Operation...........................................26 
   4.10. Compare Operation............................................27 
   4.11. Abandon Operation............................................28 
   4.12. Extended Operation...........................................28 
   4.13. Start TLS Operation..........................................29 
   5. Protocol Element Encodings and Transfer.........................31 
   5.1. Protocol Encoding.............................................31 
   5.2. Transfer Protocols............................................31 
   6. Implementation Guidelines.......................................32 
   6.1. Server Implementations........................................32 
   6.2. Client Implementations........................................32 
   7. Security Considerations.........................................32 
   8. Acknowledgements................................................33 
   9. Normative References............................................33 
   10. Editor's Address...............................................34 
   Appendix A - LDAP Result Codes.....................................35 
   A.1 Non-Error Result Codes.........................................35 
   A.2 Error Result Codes.............................................35 
   A.3 Classes and Precedence of Error Result Codes...................35 
   Appendix C - Change History........................................46 
   C.1 Changes made to RFC 2251:......................................46 
   C.2 Changes made to draft-ietf-ldapbis-protocol-00.txt:............46 
   C.3 Changes made to draft-ietf-ldapbis-protocol-01.txt:............47 
   C.4 Changes made to draft-ietf-ldapbis-protocol-02.txt:............47 
   C.5 Changes made to draft-ietf-ldapbis-protocol-03.txt:............49 
   C.6 Changes made to draft-ietf-ldapbis-protocol-04.txt:............51 
   C.7 Changes made to draft-ietf-ldapbis-protocol-05.txt:............51 
   C.8 Changes made to draft-ietf-ldapbis-protocol-06.txt:............52 
   C.9 Changes made to draft-ietf-ldapbis-protocol-07.txt:............55 
   C.10 Changes made to draft-ietf-ldapbis-protocol-08.txt:...........55 
   C.11 Changes made to draft-ietf-ldapbis-protocol-09.txt:...........55 
   C.12 Changes made to draft-ietf-ldapbis-protocol-10.txt:...........55 
   C.13 Changes made to draft-ietf-ldapbis-protocol-11.txt:...........56 
   C.14 Changes made to draft-ietf-ldapbis-protocol-12.txt:...........56 
   Appendix D - Outstanding Work Items................................56 
    
 
1. Introduction 
    
  
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   The Directory is "a collection of open systems cooperating to provide 
   directory services" [X.500]. A Directory user, which may be a human 
   or other entity, accesses the Directory through a client (or 
   Directory User Agent (DUA)). The client, on behalf of the directory 
   user, interacts with one or more servers (or Directory System Agents 
   (DSA)). Clients interact with servers using a directory access 
   protocol.  
    
   This document details the protocol elements of Lightweight Directory 
   Access Protocol, along with their semantics. Following the 
   description of protocol elements, it describes the way in which the 
   protocol is encoded and transferred. 
    
   This document is an integral part of the LDAP Technical Specification 
   [Roadmap]. 
    
   This document replaces RFC 2251. Appendix C holds a detailed log of 
   changes to RFC 2251. Prior to Working Group Last Call, this appendix 
   will be distilled to a summary of changes to RFC 2251. 
    
    
2. Conventions 
    
   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 
   "SHOULD", "SHOULD NOT", "RECOMMENDED", and "MAY" in this document are 
   to be interpreted as described in [RFC2119]. 
 
 
3. Protocol Model 
 
   The general model adopted by this protocol is one of clients 
   performing protocol operations against servers. In this model, a 
   client transmits a protocol request describing the operation to be 
   performed to a server. The server is then responsible for performing 
   the necessary operation(s) in the directory. Upon completion of the 
   operation(s), the server returns a response containing any results or 
   errors to the requesting client. 
    
   Note that although servers are required to return responses whenever 
   such responses are defined in the protocol, there is no requirement 
   for synchronous behavior on the part of either clients or servers. 
   Requests and responses for multiple operations may be exchanged 
   between a client and server in any order, provided the client 
   eventually receives a response for every request that requires one. 
 
   Note that the core protocol operations defined in this document can 
   be mapped to a subset of the X.500(1997) directory abstract service. 
   However there is not a one-to-one mapping between LDAP protocol 
   operations and DAP operations. Server implementations acting as a 
   gateway to X.500 directories may need to make multiple DAP requests. 
 
    
4. Elements of Protocol 
    
  
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   The LDAP protocol is described using Abstract Syntax Notation 1 
   (ASN.1) [X.680], and is transferred using a subset of ASN.1 Basic 
   Encoding Rules [X.690]. Section 5.1 specifies how the protocol is 
   encoded and transferred. 
 
   In order to support future Standards Track extensions to this 
   protocol, extensibility is implied where it is allowed (per ASN.1). 
   In addition, ellipses (...) have been supplied in ASN.1 types that 
   are explicitly extensible as discussed in [LDAPIANA]. Because of the 
   implied extensibility, clients and servers MUST ignore trailing 
   SEQUENCE elements whose tags they do not recognize.  
    
   Changes to the LDAP protocol other than through the extension 
   mechanisms described here require a different version number. A 
   client indicates the version it is using as part of the bind request, 
   described in section 4.2. If a client has not sent a bind, the server 
   MUST assume the client is using version 3 or later. 
    
   Clients may determine the protocol versions a server supports by 
   reading the supportedLDAPVersion attribute from the root DSE 
   [Models]. Servers which implement version 3 or later MUST provide 
   this attribute. 
    
    
4.1. Common Elements 
    
   This section describes the LDAPMessage envelope PDU (Protocol Data 
   Unit) format, as well as data type definitions, which are used in the 
   protocol operations. 
    
    
4.1.1. Message Envelope 
    
   For the purposes of protocol exchanges, all protocol operations are 
   encapsulated in a common envelope, the LDAPMessage, which is defined 
   as follows: 
    
        LDAPMessage ::= SEQUENCE { 
                messageID       MessageID, 
                protocolOp      CHOICE { 
                        bindRequest     BindRequest, 
                        bindResponse    BindResponse, 
                        unbindRequest   UnbindRequest, 
                        searchRequest   SearchRequest, 
                        searchResEntry  SearchResultEntry, 
                        searchResDone   SearchResultDone, 
                        searchResRef    SearchResultReference, 
                        modifyRequest   ModifyRequest, 
                        modifyResponse  ModifyResponse, 
                        addRequest      AddRequest, 
                        addResponse     AddResponse, 
                        delRequest      DelRequest, 
                        delResponse     DelResponse, 
                        modDNRequest    ModifyDNRequest, 
  
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                        modDNResponse   ModifyDNResponse, 
                        compareRequest  CompareRequest, 
                        compareResponse CompareResponse, 
                        abandonRequest  AbandonRequest, 
                        extendedReq     ExtendedRequest, 
                        extendedResp    ExtendedResponse, 
                        ... }, 
                controls        [0] Controls OPTIONAL } 
    
        MessageID ::= INTEGER (0 .. maxInt) 
    
        maxInt INTEGER ::= 2147483647 -- (2^^31 - 1) -- 
    
   The function of the LDAPMessage is to provide an envelope containing 
   common fields required in all protocol exchanges. At this time the 
   only common fields are the message ID and the controls. 
    
   If the server receives a PDU from the client in which the LDAPMessage 
   SEQUENCE tag cannot be recognized, the messageID cannot be parsed, 
   the tag of the protocolOp is not recognized as a request, or the 
   encoding structures or lengths of data fields are found to be 
   incorrect, then the server MAY return the Notice of Disconnection 
   described in section 4.4.1, with resultCode protocolError, and MUST 
   immediately close the connection.  
    
   In other cases where the client or server cannot parse a PDU, it 
   SHOULD abruptly close the connection where further communication 
   (including providing notice) would be pernicious. Otherwise, server 
   implementations MUST return an appropriate response to the request, 
   with the resultCode set to protocolError. 
    
   The ASN.1 type Controls is defined in section 4.1.11. 
    
    
4.1.1.1. Message ID 
    
   All LDAPMessage envelopes encapsulating responses contain the 
   messageID value of the corresponding request LDAPMessage. 
    
   The message ID of a request MUST have a non-zero value different from 
   the values of any other requests outstanding in the LDAP session of 
   which this message is a part. The zero value is reserved for the 
   unsolicited notification message. 
    
   Typical clients increment a counter for each request. 
    
   A client MUST NOT send a request with the same message ID as an 
   earlier request on the same connection unless it can be determined 
   that the server is no longer servicing the earlier request. Otherwise 
   the behavior is undefined. For operations that do not return 
   responses (unbind, abandon, and abandoned operations), the client 
   SHOULD assume the operation is in progress until a subsequent bind 
   request completes. 
 
  
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4.1.2. String Types 
    
   The LDAPString is a notational convenience to indicate that, although 
   strings of LDAPString type encode as OCTET STRING types, the 
   [ISO10646] character set (a superset of Unicode) is used, encoded 
   following the UTF-8 algorithm [RFC2279]. Note that in the UTF-8 
   algorithm characters which are the same as ASCII (0x0000 through 
   0x007F) are represented as that same ASCII character in a single 
   byte. The other byte values are used to form a variable-length 
   encoding of an arbitrary character. 
    
        LDAPString ::= OCTET STRING -- UTF-8 encoded, 
                                    -- ISO 10646 characters 
    
   The LDAPOID is a notational convenience to indicate that the 
   permitted value of this string is a (UTF-8 encoded) dotted-decimal 
   representation of an OBJECT IDENTIFIER. Although an LDAPOID is 
   encoded as an OCTET STRING, values are limited to the definition of 
   numericoid given in Section 1.3 of [Models]. 
    
        LDAPOID ::= OCTET STRING -- Constrained to numericoid [Models] 
         
   For example, 
    
        1.3.6.1.4.1.1466.1.2.3 
    
    
4.1.3. Distinguished Name and Relative Distinguished Name 
    
   An LDAPDN and a RelativeLDAPDN are respectively defined to be the 
   representation of a distinguished-name and a relative-distinguished-
   name after encoding according to the specification in [LDAPDN]. 
    
        LDAPDN ::= LDAPString  
                   -- Constrained to distinguishedName [LDAPDN] 
    
        RelativeLDAPDN ::= LDAPString  
                           -- Constrained to name-component [LDAPDN] 
    
    
4.1.4. Attribute Descriptions 
    
   The definition and encoding rules for attribute descriptions are 
   defined in Section 2.5 of [Models]. Briefly, an attribute description 
   is an attribute type and zero or more options. 
    
        AttributeDescription ::= LDAPString 
                                 -- Constrained to attributedescription 
                                 -- [Models] 
         
   An AttributeDescriptionList describes a list of 0 or more attribute 
   descriptions. (A list of zero elements has special significance in 
   the Search request.) 
  
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        AttributeDescriptionList ::= SEQUENCE OF 
                AttributeDescription 
    
 
4.1.5. Attribute Value 
    
   A field of type AttributeValue is an OCTET STRING containing an 
   encoded attribute value data type. The value is encoded according to 
   its LDAP-specific encoding definition. The LDAP-specific encoding 
   definitions for different syntaxes and attribute types may be found 
   in other documents, and in particular [Syntaxes]. 
 
        AttributeValue ::= OCTET STRING 
    
   Note that there is no defined limit on the size of this encoding; 
   thus protocol values may include multi-megabyte attributes (e.g. 
   photographs). 
    
   Attributes may be defined which have arbitrary and non-printable 
   syntax. Implementations MUST NOT display nor attempt to decode as 
   ASN.1, a value if its syntax is not known. The implementation may 
   attempt to discover the subschema of the source entry, and retrieve 
   the values of attributeTypes from it. 
    
   Clients MUST NOT send attribute values in a request that are not 
   valid according to the syntax defined for the attributes. 
    
    
4.1.6. Attribute Value Assertion 
    
   The AttributeValueAssertion type definition is similar to the one in 
   the X.500 directory standards. It contains an attribute description 
   and a matching rule assertion value suitable for that type. 
    
        AttributeValueAssertion ::= SEQUENCE { 
                attributeDesc   AttributeDescription, 
                assertionValue  AssertionValue } 
    
        AssertionValue ::= OCTET STRING 
    
   The syntax of the AssertionValue depends on the context of the LDAP 
   operation being performed. For example, the syntax of the EQUALITY 
   matching rule for an attribute is used when performing a Compare 
   operation. Often this is the same syntax used for values of the 
   attribute type, but in some cases the assertion syntax differs from 
   the value syntax. See objectIdentiferFirstComponentMatch in 
   [Syntaxes] for an example. 
    
    
4.1.7. Attribute 
    
   An attribute consists of an attribute description and one or more 
   values of that attribute description. (Though attributes MUST have at 
  
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   least one value when stored, due to access control restrictions the 
   set may be empty when transferred from the server to the client. This 
   is described in section 4.5.2, concerning the PartialAttributeList 
   type.) 
    
        Attribute ::= SEQUENCE { 
                type    AttributeDescription, 
                vals    SET OF AttributeValue } 
    
   Each attribute value is distinct in the set (no duplicates). The set 
   of attribute values is unordered. Implementations MUST NOT reply upon 
   any apparent ordering being repeatable. 
    
    
4.1.8. Matching Rule Identifier 
    
   Matching rules are defined in 4.1.3 of [Models]. A matching rule is 
   identified in the LDAP protocol by the printable representation of 
   either its numericoid, or one of its short name descriptors, e.g. 
   "caseIgnoreIA5Match" or "1.3.6.1.4.1.453.33.33". 
    
        MatchingRuleId ::= LDAPString 
    
   Servers which support matching rules for use in the extensibleMatch 
   search filter MUST list the matching rules they implement in 
   subschema entries, using the matchingRules attributes. The server 
   SHOULD also list there, using the matchingRuleUse attribute, the 
   attribute types with which each matching rule can be used. More 
   information is given in section 4.5 of [Syntaxes]. 
    
    
4.1.9. Result Message 
    
   The LDAPResult is the construct used in this protocol to return 
   success or failure indications from servers to clients. To various 
   requests, servers will return responses of LDAPResult or responses 
   containing the components of LDAPResult to indicate the final status 
   of a protocol operation request. 
    
        LDAPResult ::= SEQUENCE { 
                resultCode              ENUMERATED { 
                        success                      (0), 
                        operationsError              (1), 
                        protocolError                (2), 
                        timeLimitExceeded            (3), 
                        sizeLimitExceeded            (4), 
                        compareFalse                 (5), 
                        compareTrue                  (6), 
                        authMethodNotSupported       (7), 
                        strongAuthRequired           (8), 
                                        -- 9 reserved -- 
                        referral                     (10), 
                        adminLimitExceeded           (11), 
                        unavailableCriticalExtension (12), 
  
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                        confidentialityRequired      (13), 
                        saslBindInProgress           (14), 
                        noSuchAttribute              (16), 
                        undefinedAttributeType       (17), 
                        inappropriateMatching        (18), 
                        constraintViolation          (19), 
                        attributeOrValueExists       (20), 
                        invalidAttributeSyntax       (21), 
                                        -- 22-31 unused -- 
                        noSuchObject                 (32), 
                        aliasProblem                 (33), 
                        invalidDNSyntax              (34), 
                        -- 35 reserved for undefined isLeaf -- 
                        aliasDereferencingProblem    (36), 
                                        -- 37-47 unused -- 
                        inappropriateAuthentication  (48), 
                        invalidCredentials           (49), 
                        insufficientAccessRights     (50), 
                        busy                         (51), 
                        unavailable                  (52), 
                        unwillingToPerform           (53), 
                        loopDetect                   (54), 
                                        -- 55-63 unused -- 
                        namingViolation              (64), 
                        objectClassViolation         (65), 
                        notAllowedOnNonLeaf          (66), 
                        notAllowedOnRDN              (67), 
                        entryAlreadyExists           (68), 
                        objectClassModsProhibited    (69), 
                                -- 70 reserved for CLDAP -- 
                        affectsMultipleDSAs          (71), 
                                        -- 72-79 unused -- 
                        other                        (80), 
                        ... }, 
                        -- 81-90 reserved for APIs -- 
                matchedDN               LDAPDN, 
                diagnosticMessage       LDAPString, 
                referral                [3] Referral OPTIONAL } 
    
   The result codes enumeration is extensible as defined in Section 3.5 
   of [LDAPIANA]. The meanings of the result codes are given in Appendix 
   A. 
    
   The diagnosticMessage field of this construct may, at the server's 
   option, be used to return a string containing a textual, human-
   readable (terminal control and page formatting characters should be 
   avoided) diagnostic message. As this diagnostic message is not 
   standardized, implementations MUST NOT rely on the values returned. 
   If the server chooses not to return a textual diagnostic, the 
   diagnosticMessage field of the LDAPResult type MUST contain a zero 
   length string. 
    
   For certain result codes (typically, but not restricted to 
   noSuchObject, aliasProblem, invalidDNSyntax and 
  
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   aliasDereferencingProblem), the matchedDN field is set to the name of 
   the lowest entry (object or alias) in the directory that was matched. 
   If no aliases were dereferenced while attempting to locate the entry, 
   this will be a truncated form of the name provided, or if aliases 
   were dereferenced, of the resulting name, as defined in section 12.5 
   of [X.511]. The matchedDN field contains a zero length string with 
   all other result codes. 
    
    
4.1.10. Referral 
    
   The referral result code indicates that the contacted server does not 
   hold the target entry of the request. The referral field is present 
   in an LDAPResult if the LDAPResult.resultCode field value is 
   referral, and absent with all other result codes. It contains one or 
   more references to one or more servers or services that may be 
   accessed via LDAP or other protocols. Referrals can be returned in 
   response to any operation request (except unbind and abandon which do 
   not have responses). At least one URL MUST be present in the 
   Referral. 
    
   During a search operation, after the baseObject is located, and 
   entries are being evaluated, the referral is not returned. Instead, 
   continuation references, described in section 4.5.3, are returned 
   when the search scope spans multiple naming contexts, and several 
   different servers would need to be contacted to complete the 
   operation. 
    
        Referral ::= SEQUENCE OF LDAPURL  -- one or more 
    
        LDAPURL ::= LDAPString -- limited to characters permitted in 
                               -- URLs 
    
   If the client wishes to progress the operation, it MUST follow the 
   referral by contacting one of the servers. If multiple URLs are 
   present, the client assumes that any URL may be used to progress the 
   operation. 
    
   URLs for servers implementing the LDAP protocol are written according 
   to [LDAPURL]. If an alias was dereferenced, the <dn> part of the URL 
   MUST be present, with the new target object name. If the <dn> part is 
   present, the client MUST use this name in its next request to 
   progress the operation, and if it is not present the client will use 
   the same name as in the original request. Some servers (e.g. 
   participating in distributed indexing) may provide a different filter 
   in a referral for a search operation. If the filter part of the URL 
   is present in an LDAPURL, the client MUST use this filter in its next 
   request to progress this search, and if it is not present the client 
   MUST use the same filter as it used for that search. Other aspects of 
   the new request may be the same or different as the request which 
   generated the referral. 
    


  
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   Note that UTF-8 characters appearing in a DN or search filter may not 
   be legal for URLs (e.g. spaces) and MUST be escaped using the % 
   method in [RFC2396]. 
    
   Other kinds of URLs may be returned, so long as the operation could 
   be performed using that protocol. 
    
    
4.1.11. Controls 
    
   A control is a way to specify extension information for an LDAP 
   message. A control only alters the semantics of the message it is 
   attached to. 
    
        Controls ::= SEQUENCE OF Control 
    
        Control ::= SEQUENCE { 
                controlType             LDAPOID, 
                criticality             BOOLEAN DEFAULT FALSE, 
                controlValue            OCTET STRING OPTIONAL } 
    
   The controlType field MUST be a UTF-8 encoded dotted-decimal 
   representation of an OBJECT IDENTIFIER which uniquely identifies the 
   control. This prevents conflicts between control names. 
    
   The criticality field is either TRUE or FALSE and only applies to 
   request messages that have a corresponding response message. For all 
   other messages (such as abandonRequest, unbindRequest and all 
   response messages), the criticality field is treated as FALSE. 
    
   If the server recognizes the control type and it is appropriate for 
   the operation, the server will make use of the control when 
   performing the operation. 
    
   If the server does not recognize the control type or it is not 
   appropriate for the operation, and the criticality field is TRUE, the 
   server MUST NOT perform the operation, and MUST instead return the 
   resultCode unavailableCriticalExtension. 
    
   If the control is unrecognized or inappropriate but the criticality 
   field is FALSE, the server MUST ignore the control. 
    
   The controlValue contains any information associated with the 
   control, and its format is defined for the control. Implementations 
   MUST be prepared to handle arbitrary contents of the controlValue 
   octet string, including zero bytes. It is absent only if there is no 
   value information which is associated with a control of its type. 
    
   This document does not specify any controls. Controls may be 
   specified in other documents. The specification of a control consists 
   of: 
    
   - the OBJECT IDENTIFIER assigned to the control, 
    
  
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   - whether the control is always noncritical, always critical, or 
     critical at the client's option, 
    
   - the format of the controlValue contents of the control, 
    
   - the semantics of the control, 
    
   - and optionally, semantics regarding the combination of the control 
     with other controls. 
    
   Servers list the controlType of all request controls they recognize 
   in the supportedControl attribute [Models] in the root DSE. 
    
   Controls should not be combined unless the semantics of the 
   combination has been specified. The semantics of control 
   combinations, if specified, are generally found in the control 
   specification most recently published. In the absence of combination 
   semantics, the behavior of the operation is undefined.  
   Additionally, the order of a combination of controls in the SEQUENCE 
   is ignored unless the control specification(s) describe(s) 
   combination semantics. 
    
    
4.2. Bind Operation 
    
   The function of the Bind Operation is to allow authentication 
   information to be exchanged between the client and server. Prior to 
   the first BindRequest, the implied identity is anonymous. Refer to 
   [AuthMeth] for the authentication-related semantics of this 
   operation.  
    
   The Bind Request is defined as follows: 
    
        BindRequest ::= [APPLICATION 0] SEQUENCE { 
                version                 INTEGER (1 .. 127), 
                name                    LDAPDN, 
                authentication          AuthenticationChoice } 
    
        AuthenticationChoice ::= CHOICE { 
                simple                  [0] OCTET STRING, 
                                         -- 1 and 2 reserved 
                sasl                    [3] SaslCredentials, 
                ... } 
    
        SaslCredentials ::= SEQUENCE { 
                mechanism               LDAPString, 
                credentials             OCTET STRING OPTIONAL } 
    
   Parameters of the Bind Request are: 
    
   - version: A version number indicating the version of the protocol 
     to be used in this protocol session. This document describes 
     version 3 of the LDAP protocol. Note that there is no version 
     negotiation, and the client just sets this parameter to the 
  
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     version it desires. If the server does not support the specified 
     version, it responds with protocolError in the resultCode field of 
     the BindResponse. 
    
   - name: The name of the directory object that the client wishes to 
     bind as. This field may take on a null value (a zero length 
     string) for the purposes of anonymous binds ([AuthMeth] section 7) 
     or when using SASL authentication ([AuthMeth] section 4.3). Server 
     behavior is undefined when the name is a null value, simple 
     authentication is used, and a password is specified. The server 
     SHOULD NOT perform any alias dereferencing in determining the 
     object to bind as. 
    
   - authentication: information used to authenticate the name, if any, 
     provided in the Bind Request. This type is extensible as defined 
     in Section 3.6 of [LDAPIANA]. Servers that do not support a choice 
     supplied by a client will return authMethodNotSupported in the 
     result code of the BindResponse. 
    
   Authorization is the use of this authentication information when 
   performing operations. Authorization MAY be affected by factors 
   outside of the LDAP Bind Request, such as lower layer security 
   services. 
    
    
4.2.1. Processing of the Bind Request 
    
   Upon receipt of a BindRequest, the server MUST ensure there are no 
   outstanding operations in progress on the connection (This simplifies 
   server implementation). The server then proceeds to authenticate the 
   client in either a single-step, or multi-step bind process. Each step 
   requires the server to return a BindResponse to indicate the status 
   of authentication.  
    
   If the client did not bind before sending a request and receives an 
   operationsError, it may then send a Bind Request. If this also fails 
   or the client chooses not to bind on the existing connection, it may 
   close the connection, reopen it and begin again by first sending a 
   PDU with a Bind Request. This will aid in interoperating with servers 
   implementing other versions of LDAP. 
    
   Clients MAY send multiple Bind Requests on a connection to change 
   their credentials. Authentication from earlier binds is subsequently 
   ignored. A failed or abandoned Bind Operation has the effect of 
   leaving the connection in an anonymous state. To arrive at a known 
   authentication state after abandoning a bind operation, clients may 
   unbind, rebind, or make use of the BindResponse. If a SASL transfer 
   encryption or integrity mechanism has been negotiated, and that 
   mechanism does not support the changing of credentials from one 
   identity to another, then the client MUST instead establish a new 
   connection. 
    
   For some SASL authentication mechanisms, it may be necessary for the 
   client to invoke the BindRequest multiple times. This is indicated by 
  
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   the server sending a BindResponse with the resultCode set to 
   saslBindInProgress. This indicates that the server requires the 
   client to send a new bind request, with the same sasl mechanism, to 
   continue the authentication process. If at any stage the client 
   wishes to abort the bind process it MAY unbind and then drop the 
   underlying connection. Clients MUST NOT invoke operations between two 
   Bind Requests made as part of a multi-stage bind. 
    
   A client may abort a SASL bind negotiation by sending a BindRequest 
   with a different value in the mechanism field of SaslCredentials, or 
   an AuthenticationChoice other than sasl. 
    
   If the client sends a BindRequest with the sasl mechanism field as an 
   empty string, the server MUST return a BindResponse with 
   authMethodNotSupported as the resultCode. This will allow clients to 
   abort a negotiation if it wishes to try again with the same SASL 
   mechanism. 
    
    
4.2.2. Bind Response 
    
   The Bind Response is defined as follows. 
    
        BindResponse ::= [APPLICATION 1] SEQUENCE { 
             COMPONENTS OF LDAPResult, 
             serverSaslCreds    [7] OCTET STRING OPTIONAL } 
    
   BindResponse consists simply of an indication from the server of the 
   status of the client's request for authentication. 
    
   A successful bind operation is indicated by a BindResponse with a 
   resultCode set to success (0). Otherwise, an appropriate resultCode 
   is set in the BindResponse. For bind, the protocolError (2) 
   resultCode may be used to indicate that the version number supplied 
   by the client is unsupported. 
    
   If the server does not support the client's requested protocol 
   version, it MUST set the resultCode to protocolError. 
    
   If the client receives a BindResponse response where the resultCode 
   was protocolError, it MUST close the connection as the server will be 
   unwilling to accept further operations. (This is for compatibility 
   with earlier versions of LDAP, in which the bind was always the first 
   operation, and there was no negotiation.) 
    
   The serverSaslCreds are used as part of a SASL-defined bind mechanism 
   to allow the client to authenticate the server to which it is 
   communicating, or to perform "challenge-response" authentication. If 
   the client bound with the simple choice, or the SASL mechanism does 
   not require the server to return information to the client, then this 
   field is not to be included in the result. 
    
    
4.3. Unbind Operation 
  
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   The function of the Unbind Operation is to terminate a protocol 
   session. The Unbind Operation is defined as follows: 
    
        UnbindRequest ::= [APPLICATION 2] NULL 
    
   The Unbind Operation has no response defined. Upon transmission of an 
   UnbindRequest, a protocol client MUST assume that the protocol 
   session is terminated. Upon receipt of an UnbindRequest, a protocol 
   server MUST assume that the requesting client has terminated the 
   session and that all outstanding requests may be discarded, and MUST 
   close the connection. 
    
    
4.4. Unsolicited Notification 
    
   An unsolicited notification is an LDAPMessage sent from the server to 
   the client which is not in response to any LDAPMessage received by 
   the server. It is used to signal an extraordinary condition in the 
   server or in the connection between the client and the server. The 
   notification is of an advisory nature, and the server will not expect 
   any response to be returned from the client. 
    
   The unsolicited notification is structured as an LDAPMessage in which 
   the messageID is 0 and protocolOp is of the extendedResp form. The 
   responseName field of the ExtendedResponse is present. The LDAPOID 
   value MUST be unique for this notification, and not be used in any 
   other situation. 
    
   One unsolicited notification (Notice of Disconnection) is defined in 
   this document. 
    
    
4.4.1. Notice of Disconnection 
    
   This notification may be used by the server to advise the client that 
   the server is about to close the connection due to an error 
   condition. Note that this notification is NOT a response to an unbind 
   requested by the client: the server MUST follow the procedures of 
   section 4.3. This notification is intended to assist clients in 
   distinguishing between an error condition and a transient network 
   failure. As with a connection close due to network failure, the 
   client MUST NOT assume that any outstanding requests which modified 
   the directory have succeeded or failed. 
    
   The responseName is 1.3.6.1.4.1.1466.20036, the response field is 
   absent, and the resultCode is used to indicate the reason for the 
   disconnection. 
    
   The following resultCode values are to be used in this notification: 
    
   - protocolError: The server has received data from the client in 
     which the LDAPMessage structure could not be parsed. 
    
  
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   - strongAuthRequired: The server has detected that an established 
     underlying security association protecting communication between 
     the client and server has unexpectedly failed or been compromised. 
    
   - unavailable: This server will stop accepting new connections and 
     operations on all existing connections, and be unavailable for an 
     extended period of time. The client may make use of an alternative 
     server. 
    
   After sending this notice, the server MUST close the connection. 
   After receiving this notice, the client MUST NOT transmit any further 
   on the connection, and may abruptly close the connection. 
    
    
4.5. Search Operation 
    
   The Search Operation allows a client to request that a search be 
   performed on its behalf by a server. This can be used to read 
   attributes from a single entry, from entries immediately below a 
   particular entry, or a whole subtree of entries. 
    
    
4.5.1. Search Request 
    
   The Search Request is defined as follows: 
    
        SearchRequest ::= [APPLICATION 3] SEQUENCE { 
                baseObject      LDAPDN, 
                scope           ENUMERATED { 
                        baseObject              (0), 
                        singleLevel             (1), 
                        wholeSubtree            (2) }, 
                derefAliases    ENUMERATED { 
                        neverDerefAliases       (0), 
                        derefInSearching        (1), 
                        derefFindingBaseObj     (2), 
                        derefAlways             (3) }, 
                sizeLimit       INTEGER (0 .. maxInt), 
                timeLimit       INTEGER (0 .. maxInt), 
                typesOnly       BOOLEAN, 
                filter          Filter, 
                attributes      AttributeDescriptionList } 
    
        Filter ::= CHOICE { 
                and             [0] SET SIZE (1..MAX) OF Filter, 
                or              [1] SET SIZE (1..MAX) OF Filter, 
                not             [2] Filter, 
                equalityMatch   [3] AttributeValueAssertion, 
                substrings      [4] SubstringFilter, 
                greaterOrEqual  [5] AttributeValueAssertion, 
                lessOrEqual     [6] AttributeValueAssertion, 
                present         [7] AttributeDescription, 
                approxMatch     [8] AttributeValueAssertion, 
                extensibleMatch [9] MatchingRuleAssertion } 
  
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        SubstringFilter ::= SEQUENCE { 
                type            AttributeDescription, 
                -- at least one must be present, 
                -- initial and final can occur at most once 
                substrings      SEQUENCE OF CHOICE { 
                        initial [0] AssertionValue, 
                        any     [1] AssertionValue, 
                        final   [2] AssertionValue } } 
    
        MatchingRuleAssertion ::= SEQUENCE { 
                matchingRule    [1] MatchingRuleId OPTIONAL, 
                type            [2] AttributeDescription OPTIONAL, 
                matchValue      [3] AssertionValue, 
                dnAttributes    [4] BOOLEAN DEFAULT FALSE } 
    
   Parameters of the Search Request are: 
    
   - baseObject: An LDAPDN that is the base object entry relative to 
     which the search is to be performed. 
    
   - scope: An indicator of the scope of the search to be performed. 
     The semantics of the possible values of this field are identical 
     to the semantics of the scope field in the X.511 Search Operation. 
    
   - derefAliases: An indicator as to how alias objects (as defined in 
     X.501) are to be handled in searching. The semantics of the 
     possible values of this field are: 
    
             neverDerefAliases: do not dereference aliases in searching 
             or in locating the base object of the search; 
    
             derefInSearching: dereference aliases in subordinates of 
             the base object in searching, but not in locating the base 
             object of the search; 
    
             derefFindingBaseObj: dereference aliases in locating the 
             base object of the search, but not when searching 
             subordinates of the base object; 
    
             derefAlways: dereference aliases both in searching and in 
             locating the base object of the search. 
    
   - sizeLimit: A size limit that restricts the maximum number of 
     entries to be returned as a result of the search. A value of 0 in 
     this field indicates that no client-requested size limit 
     restrictions are in effect for the search. Servers may enforce a 
     maximum number of entries to return. 
    
   - timeLimit: A time limit that restricts the maximum time (in 
     seconds) allowed for a search. A value of 0 in this field 
     indicates that no client-requested time limit restrictions are in 
     effect for the search. 
    
  
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   - typesOnly: An indicator as to whether search results will contain 
     both attribute descriptions and values, or just attribute 
     descriptions. Setting this field to TRUE causes only attribute 
     descriptions (no values) to be returned. Setting this field to 
     FALSE causes both attribute descriptions and values to be 
     returned. 
    
   - filter: A filter that defines the conditions that must be 
     fulfilled in order for the search to match a given entry. 
      
     The 'and', 'or' and 'not' choices can be used to form combinations 
     of filters. At least one filter element MUST be present in an 
     'and' or 'or' choice. The others match against individual 
     attribute values of entries in the scope of the search. 
     (Implementor's note: the 'not' filter is an example of a tagged 
     choice in an implicitly-tagged module. In BER this is treated as 
     if the tag was explicit.) 
    
     A server MUST evaluate filters according to the three-valued logic 
     of X.511 (1993) section 7.8.1. In summary, a filter is evaluated 
     to either "TRUE", "FALSE" or "Undefined". If the filter evaluates 
     to TRUE for a particular entry, then the attributes of that entry 
     are returned as part of the search result (subject to any 
     applicable access control restrictions). If the filter evaluates 
     to FALSE or Undefined, then the entry is ignored for the search. 
      
     A filter of the "and" choice is TRUE if all the filters in the SET 
     OF evaluate to TRUE, FALSE if at least one filter is FALSE, and 
     otherwise Undefined. A filter of the "or" choice is FALSE if all 
     of the filters in the SET OF evaluate to FALSE, TRUE if at least 
     one filter is TRUE, and Undefined otherwise. A filter of the "not" 
     choice is TRUE if the filter being negated is FALSE, FALSE if it 
     is TRUE, and Undefined if it is Undefined. 
      
     The present match evaluates to TRUE where there is an attribute or 
     subtype of the specified attribute description present in an 
     entry, and FALSE otherwise (including a presence test with an 
     unrecognized attribute description.) 
      
     The matching rule for equalityMatch filter items is defined by the 
     EQUALITY matching rule for the attribute type. 
    
     The matching rule and assertion syntax for AssertionValues in a 
     substrings filter item is defined by the SUBSTR matching rule for 
     the attribute type. 
    
     The matching rule for greaterOrEqual and lessOrEqual filter items 
     is defined by the ORDERING matching rule for the attribute type. 
    
     The matching rule for approxMatch filter items is implementation-
     defined. If approximate matching is not supported by the server, 
     the filter item should be treated as an equalityMatch. 
      
     The extensibleMatch is new in this version of LDAP. If the 
  
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     matchingRule field is absent, the type field MUST be present, and 
     the equality match is performed for that type. If the type field 
     is absent and matchingRule is present, the matchValue is compared 
     against all attributes in an entry which support that 
     matchingRule, and the matchingRule determines the syntax for the 
     assertion value (the filter item evaluates to TRUE if it matches 
     with at least one attribute in the entry, FALSE if it does not 
     match any attribute in the entry, and Undefined if the 
     matchingRule is not recognized or the assertionValue cannot be 
     parsed.) If the type field is present and matchingRule is present, 
     the matchingRule MUST be one permitted for use with that type, 
     otherwise the filter item is undefined. If the dnAttributes field 
     is set to TRUE, the match is applied against all the 
     AttributeValueAssertions in an entry's distinguished name as well, 
     and also evaluates to TRUE if there is at least one attribute in 
     the distinguished name for which the filter item evaluates to 
     TRUE. (Editors note: The dnAttributes field is present so that 
     there does not need to be multiple versions of generic matching 
     rules such as for word matching, one to apply to entries and 
     another to apply to entries and dn attributes as well). 
      
     A filter item evaluates to Undefined when the server would not be 
     able to determine whether the assertion value matches an entry. If 
     an attribute description in an equalityMatch, substrings, 
     greaterOrEqual, lessOrEqual, approxMatch or extensibleMatch filter 
     is not recognized by the server, a matching rule id in the 
     extensibleMatch is not recognized by the server, the assertion 
     value cannot be parsed, or the type of filtering requested is not 
     implemented, then the filter is Undefined. Thus for example if a 
     server did not recognize the attribute type shoeSize, a filter of 
     (shoeSize=*) would evaluate to FALSE, and the filters 
     (shoeSize=12), (shoeSize>=12) and (shoeSize<=12) would evaluate to 
     Undefined. 
      
     Servers MUST NOT return errors if attribute descriptions or 
     matching rule ids are not recognized, or assertion values cannot 
     be parsed. More details of filter processing are given in section 
     7.8 of [X.511]. 
    
   - attributes: A list of the attributes to be returned from each 
     entry which matches the search filter. There are two special 
     values which may be used: an empty list with no attributes, and 
     the attribute description string "*". Both of these signify that 
     all user attributes are to be returned. (The "*" allows the client 
     to request all user attributes in addition to any specified 
     operational attributes). 
      
     Attributes MUST be named at most once in the list, and are 
     returned at most once in an entry. If there are attribute 
     descriptions in the list which are not recognized, they are 
     ignored by the server. 
      
     If the client does not want any attributes returned, it can 
     specify a list containing only the attribute with OID "1.1". This 
  
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     OID was chosen arbitrarily and does not correspond to any 
     attribute in use. 
      
     Client implementors should note that even if all user attributes 
     are requested, some attributes of the entry may not be included in 
     search results due to access controls or other restrictions. 
     Furthermore, servers will not return operational attributes, such 
     as objectClasses or attributeTypes, unless they are listed by 
     name, since there may be extremely large number of values for 
     certain operational attributes. (A list of operational attributes 
     for use in LDAP is given in [Syntaxes].) 
    
   Note that an X.500 "list"-like operation can be emulated by the 
   client requesting a one-level LDAP search operation with a filter 
   checking for the presence of the objectClass attribute, and that an 
   X.500 "read"-like operation can be emulated by a base object LDAP 
   search operation with the same filter. A server which provides a 
   gateway to X.500 is not required to use the Read or List operations, 
   although it may choose to do so, and if it does, it must provide the 
   same semantics as the X.500 search operation. 
    
    
4.5.2. Search Result 
    
   The results of the search attempted by the server upon receipt of a 
   Search Request are returned in Search Responses, which are LDAP 
   messages containing either SearchResultEntry, SearchResultReference, 
   or SearchResultDone data types. 
    
        SearchResultEntry ::= [APPLICATION 4] SEQUENCE { 
                objectName      LDAPDN, 
                attributes      PartialAttributeList } 
    
        PartialAttributeList ::= SEQUENCE OF SEQUENCE { 
                type    AttributeDescription, 
                vals    SET OF AttributeValue } 
        -- implementors should note that the PartialAttributeList may 
        -- have zero elements (if none of the attributes of that entry 
        -- were requested, or could be returned), and that the vals set 
        -- may also have zero elements (if types only was requested, or 
        -- all values were excluded from the result.) 
    
        SearchResultReference ::= [APPLICATION 19] SEQUENCE OF LDAPURL 
        -- at least one LDAPURL element must be present 
    
        SearchResultDone ::= [APPLICATION 5] LDAPResult 
    
   Upon receipt of a Search Request, a server will perform the necessary 
   search of the DIT. 
    
   If the LDAP session is operating over a connection-oriented transport 
   such as TCP, the server will return to the client a sequence of 
   responses in separate LDAP messages. There may be zero or more 
   responses containing SearchResultEntry, one for each entry found 
  
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   during the search. There may also be zero or more responses 
   containing SearchResultReference, one for each area not explored by 
   this server during the search. The SearchResultEntry and 
   SearchResultReference PDUs may come in any order. Following all the 
   SearchResultReference responses and all SearchResultEntry responses 
   to be returned by the server, the server will return a response 
   containing the SearchResultDone, which contains an indication of 
   success, or detailing any errors that have occurred. 
    
   Each entry returned in a SearchResultEntry will contain all 
   appropriate attributes as specified in the attributes field of the 
   Search Request. Return of attributes is subject to access control and 
   other administrative policy. 
    
   Some attributes may be constructed by the server and appear in a 
   SearchResultEntry attribute list, although they are not stored 
   attributes of an entry. Clients SHOULD NOT assume that all attributes 
   can be modified, even if permitted by access control. 
    
   If the server's schema defines a textual name for an attribute type, 
   it MUST use a textual name for attributes of that attribute type by 
   specifying one of the textual names as the value of the attribute 
   type. Otherwise, the server uses the object identifier for the 
   attribute type by specifying the object identifier, in ldapOID form, 
   as the value of attribute type. 
    
    
4.5.3. Continuation References in the Search Result 
    
   If the server was able to locate the entry referred to by the 
   baseObject but was unable to search all the entries in the scope at 
   and under the baseObject, the server may return one or more 
   SearchResultReference entries, each containing a reference to another 
   set of servers for continuing the operation. A server MUST NOT return 
   any SearchResultReference if it has not located the baseObject and 
   thus has not searched any entries; in this case it would return a 
   SearchResultDone containing a referral resultCode. 
    
   If a server holds a copy or partial copy of the subordinate naming 
   context, it may use the search filter to determine whether or not to 
   return a SearchResultReference response. Otherwise 
   SearchResultReference responses are always returned when in scope. 
    
   The SearchResultReference is of the same data type as the Referral. 
   URLs for servers implementing the LDAP protocol are written according 
   to [LDAPURL]. The <dn> part MUST be present in the URL, with the new 
   target object name. The client MUST use this name in its next 
   request. Some servers (e.g. part of a distributed index exchange 
   system) may provide a different filter in the URLs of the 
   SearchResultReference. If the filter part of the URL is present in an 
   LDAP URL, the client MUST use the new filter in its next request to 
   progress the search, and if the filter part is absent the client will 
   use again the same filter. If the originating search scope was 
   singleLevel, the scope part of the URL will be baseObject. Other 
  
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   aspects of the new search request may be the same or different as the 
   search which generated the continuation references. 
   Other kinds of URLs may be returned so long as the operation could be 
   performed using that protocol. 
    
   The name of an unexplored subtree in a SearchResultReference need not 
   be subordinate to the base object. 
    
   In order to complete the search, the client MUST issue a new search 
   operation for each SearchResultReference that is returned. Note that 
   the abandon operation described in section 4.11 applies only to a 
   particular operation sent on a connection between a client and 
   server, and if the client has multiple outstanding search operations, 
   it MUST abandon each operation individually. 
    
    
4.5.3.1. Example 
    
   For example, suppose the contacted server (hosta) holds the entry 
   "DC=Example,DC=NET" and the entry "CN=Manager,DC=Example,DC=NET". It 
   knows that either LDAP-capable servers (hostb) or (hostc) hold 
   "OU=People,DC=Example,DC=NET" (one is the master and the other server 
   a shadow), and that LDAP-capable server (hostd) holds the subtree 
   "OU=Roles,DC=Example,DC=NET". If a subtree search of 
   "DC=Example,DC=NET" is requested to the contacted server, it may 
   return the following: 
    
     SearchResultEntry for DC=Example,DC=NET 
     SearchResultEntry for CN=Manager,DC=Example,DC=NET 
     SearchResultReference { 
       ldap://hostb/OU=People,DC=Example,DC=NET 
       ldap://hostc/OU=People,DC=Example,DC=NET 
     } 
     SearchResultReference { 
       ldap://hostd/OU=Roles,DC=Example,DC=NET 
     } 
     SearchResultDone (success) 
    
   Client implementors should note that when following a 
   SearchResultReference, additional SearchResultReference may be 
   generated. Continuing the example, if the client contacted the server 
   (hostb) and issued the search for the subtree 
   "OU=People,DC=Example,DC=NET", the server might respond as follows: 
    
     SearchResultEntry for OU=People,DC=Example,DC=NET 
     SearchResultReference { 
       ldap://hoste/OU=Managers,OU=People,DC=Example,DC=NET 
     } 
     SearchResultReference { 
       ldap://hostf/OU=Consultants,OU=People,DC=Example,DC=NET 
     } 
     SearchResultDone (success) 
    

  
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   If the contacted server does not hold the base object for the search, 
   then it will return a referral to the client. For example, if the 
   client requests a subtree search of "DC=Example,DC=ORG" to hosta, the 
   server may return only a SearchResultDone containing a referral. 
    
     SearchResultDone (referral) { 
       ldap://hostg/DC=Example,DC=ORG??sub 
     } 
    
    
4.6. Modify Operation 
    
   The Modify Operation allows a client to request that a modification 
   of an entry be performed on its behalf by a server. The Modify 
   Request is defined as follows: 
    
        ModifyRequest ::= [APPLICATION 6] SEQUENCE { 
                object          LDAPDN, 
                modification    SEQUENCE OF SEQUENCE { 
                        operation       ENUMERATED { 
                                                add     (0), 
                                                delete  (1), 
                                                replace (2) }, 
                        modification    AttributeTypeAndValues } } 
    
        AttributeTypeAndValues ::= SEQUENCE { 
                type    AttributeDescription, 
                vals    SET OF AttributeValue } 
    
   Parameters of the Modify Request are: 
    
   - object: The object to be modified. The value of this field 
     contains the DN of the entry to be modified. The server will not 
     perform any alias dereferencing in determining the object to be 
     modified. 
    
   - modification: A list of modifications to be performed on the 
     entry. The entire list of entry modifications MUST be performed in 
     the order they are listed, as a single atomic operation. While 
     individual modifications may violate the directory schema, the 
     resulting entry after the entire list of modifications is 
     performed MUST conform to the requirements of the directory 
     schema. The values that may be taken on by the 'operation' field 
     in each modification construct have the following semantics 
     respectively: 
    
             add: add values listed to the given attribute, creating the 
             attribute if necessary; 
    
             delete: delete values listed from the given attribute, 
             removing the entire attribute if no values are listed, or 
             if all current values of the attribute are listed for 
             deletion; 
    
  
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             replace: replace all existing values of the given attribute 
             with the new values listed, creating the attribute if it 
             did not already exist. A replace with no value will delete 
             the entire attribute if it exists, and is ignored if the 
             attribute does not exist. 
    
   The result of the modification attempted by the server upon receipt 
   of a Modify Request is returned in a Modify Response, defined as 
   follows: 
    
        ModifyResponse ::= [APPLICATION 7] LDAPResult 
    
   Upon receipt of a Modify Request, a server will perform the necessary 
   modifications to the DIT. 
    
   The server will return to the client a single Modify Response 
   indicating either the successful completion of the DIT modification, 
   or the reason that the modification failed. Note that due to the 
   requirement for atomicity in applying the list of modifications in 
   the Modify Request, the client may expect that no modifications of 
   the DIT have been performed if the Modify Response received indicates 
   any sort of error, and that all requested modifications have been 
   performed if the Modify Response indicates successful completion of 
   the Modify Operation. If the connection fails, whether the 
   modification occurred or not is indeterminate. 
    
   The Modify Operation cannot be used to remove from an entry any of 
   its distinguished values, those values which form the entry's 
   relative distinguished name. An attempt to do so will result in the 
   server returning the error notAllowedOnRDN. The Modify DN Operation 
   described in section 4.9 is used to rename an entry. 
    
   Note that due to the simplifications made in LDAP, there is not a 
   direct mapping of the modifications in an LDAP ModifyRequest onto the 
   EntryModifications of a DAP ModifyEntry operation, and different 
   implementations of LDAP-DAP gateways may use different means of 
   representing the change. If successful, the final effect of the 
   operations on the entry MUST be identical. 
    
    
4.7. Add Operation 
    
   The Add Operation allows a client to request the addition of an entry 
   into the directory. The Add Request is defined as follows: 
    
        AddRequest ::= [APPLICATION 8] SEQUENCE { 
                entry           LDAPDN, 
                attributes      AttributeList } 
    
        AttributeList ::= SEQUENCE OF SEQUENCE { 
                type    AttributeDescription, 
                vals    SET OF AttributeValue } 
    
   Parameters of the Add Request are: 
  
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   - entry: the Distinguished Name of the entry to be added. Note that 
     the server will not dereference any aliases in locating the entry 
     to be added. 
    
   - attributes: the list of attributes that make up the content of the 
     entry being added. Clients MUST include distinguished values 
     (those forming the entry's own RDN) in this list, the objectClass 
     attribute, and values of any mandatory attributes of the listed 
     object classes. Clients MUST NOT supply NO-USER-MODIFICATION 
     attributes such as the createTimestamp or creatorsName attributes, 
     since the server maintains these automatically. 
    
   The entry named in the entry field of the AddRequest MUST NOT exist 
   for the AddRequest to succeed. The parent of the object and alias 
   entries to be added MUST exist. For example, if the client attempted 
   to add "CN=JS,DC=Example,DC=NET", the "DC=Example,DC=NET" entry did 
   not exist, and the "DC=NET" entry did exist, then the server would 
   return the error noSuchObject with the matchedDN field containing 
   "DC=NET". If the parent entry exists but is not in a naming context 
   held by the server, the server SHOULD return a referral to the server 
   holding the parent entry. 
    
   Server implementations SHOULD NOT restrict where entries can be 
   located in the directory unless DIT structure rules are in place. 
   Some servers MAY allow the administrator to restrict the classes of 
   entries which can be added to the directory. 
    
   Upon receipt of an Add Request, a server will attempt to add the 
   requested entry. The result of the add attempt will be returned to 
   the client in the Add Response, defined as follows: 
    
        AddResponse ::= [APPLICATION 9] LDAPResult 
    
   A response of success indicates that the new entry is present in the 
   directory. 
    
    
4.8. Delete Operation 
    
   The Delete Operation allows a client to request the removal of an 
   entry from the directory. The Delete Request is defined as follows: 
    
        DelRequest ::= [APPLICATION 10] LDAPDN 
    
   The Delete Request consists of the Distinguished Name of the entry to 
   be deleted. Note that the server will not dereference aliases while 
   resolving the name of the target entry to be removed, and that only 
   leaf entries (those with no subordinate entries) can be deleted with 
   this operation. 
    
   The result of the delete attempted by the server upon receipt of a 
   Delete Request is returned in the Delete Response, defined as 
   follows: 
  
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        DelResponse ::= [APPLICATION 11] LDAPResult 
    
   Upon receipt of a Delete Request, a server will attempt to perform 
   the entry removal requested. The result of the delete attempt will be 
   returned to the client in the Delete Response. 
    
    
4.9. Modify DN Operation 
    
   The Modify DN Operation allows a client to change the leftmost (least 
   significant) component of the name of an entry in the directory, 
   and/or to move a subtree of entries to a new location in the 
   directory. The Modify DN Request is defined as follows: 
    
        ModifyDNRequest ::= [APPLICATION 12] SEQUENCE { 
                entry           LDAPDN, 
                newrdn          RelativeLDAPDN, 
                deleteoldrdn    BOOLEAN, 
                newSuperior     [0] LDAPDN OPTIONAL } 
    
   Parameters of the Modify DN Request are: 
    
   - entry: the Distinguished Name of the entry to be changed. This 
     entry may or may not have subordinate entries. Note that the 
     server will not dereference any aliases in locating the entry to 
     be changed. 
    
   - newrdn: the RDN that will form the leftmost component of the new 
     name of the entry. 
    
   - deleteoldrdn: a boolean parameter that controls whether the old 
     RDN attribute values are to be retained as attributes of the 
     entry, or deleted from the entry. 
    
   - newSuperior: if present, this is the Distinguished Name of an 
     existing object entry which becomes the immediate superior of the 
     existing entry. 
    
   The result of the name change attempted by the server upon receipt of 
   a Modify DN Request is returned in the Modify DN Response, defined as 
   follows: 
    
        ModifyDNResponse ::= [APPLICATION 13] LDAPResult 
    
   Upon receipt of a ModifyDNRequest, a server will attempt to perform 
   the name change. The result of the name change attempt will be 
   returned to the client in the Modify DN Response. 
    
   For example, if the entry named in the "entry" parameter was "cn=John 
   Smith,c=US", the newrdn parameter was "cn=John Cougar Smith", and the 
   newSuperior parameter was absent, then this operation would attempt 
   to rename the entry to be "cn=John Cougar Smith,c=US". If there was 

  
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   already an entry with that name, the operation would fail with error 
   code entryAlreadyExists. 
    
   If the deleteoldrdn parameter is TRUE, the values forming the old RDN 
   are deleted from the entry. If the deleteoldrdn parameter is FALSE, 
   the values forming the old RDN will be retained as non-distinguished 
   attribute values of the entry. The server may not perform the 
   operation and return an error code if the setting of the deleteoldrdn 
   parameter would cause a schema inconsistency in the entry. 
    
   Note that X.500 restricts the ModifyDN operation to only affect 
   entries that are contained within a single server. If the LDAP server 
   is mapped onto DAP, then this restriction will apply, and the 
   resultCode affectsMultipleDSAs will be returned if this error 
   occurred. In general clients MUST NOT expect to be able to perform 
   arbitrary movements of entries and subtrees between servers. 
    
    
4.10. Compare Operation 
    
   The Compare Operation allows a client to compare an assertion 
   provided with an entry in the directory. The Compare Request is 
   defined as follows: 
    
        CompareRequest ::= [APPLICATION 14] SEQUENCE { 
                entry           LDAPDN, 
                ava             AttributeValueAssertion } 
    
   Parameters of the Compare Request are: 
    
   - entry: the name of the entry to be compared with. Note that the 
     server SHOULD NOT dereference any aliases in locating the entry to 
     be compared with. 
    
   - ava: the assertion with which an attribute in the entry is to be 
     compared. 
    
   The result of the compare attempted by the server upon receipt of a 
   Compare Request is returned in the Compare Response, defined as 
   follows: 
    
        CompareResponse ::= [APPLICATION 15] LDAPResult 
    
   Upon receipt of a Compare Request, a server will attempt to perform 
   the requested comparison using the EQUALITY matching rule for the 
   attribute type. The result of the comparison will be returned to the 
   client in the Compare Response. Note that errors and the result of 
   comparison are all returned in the same construct. 
    
   Note that some directory systems may establish access controls which 
   permit the values of certain attributes (such as userPassword) to be 
   compared but not interrogated by other means. 
    
    
  
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4.11. Abandon Operation 
    
   The function of the Abandon Operation is to allow a client to request 
   that the server abandon an outstanding operation. The Abandon Request 
   is defined as follows: 
    
        AbandonRequest ::= [APPLICATION 16] MessageID 
    
   The MessageID MUST be that of an operation which was requested 
   earlier in this connection. The abandon request itself has its own 
   message id. This is distinct from the id of the earlier operation 
   being abandoned. 
    
   There is no response defined in the Abandon Operation. Upon 
   transmission of an Abandon Operation, the server MAY abandon the 
   operation identified by the Message ID in the Abandon Request. 
   Operation responses are not sent for successfully abandoned 
   operations. Clients can determine that an operation has been 
   abandoned by performing a subsequent bind operation. 
    
   Abandon and Unbind operations cannot be abandoned. The ability to 
   abandon other (particularly update) operations is at the discretion 
   of the server. 
    
   In the event that a server receives an Abandon Request on a Search 
   Operation in the midst of transmitting responses to the search, that 
   server MUST cease transmitting entry responses to the abandoned 
   request immediately, and MUST NOT send the SearchResponseDone. Of 
   course, the server MUST ensure that only properly encoded LDAPMessage 
   PDUs are transmitted. 
    
   Clients MUST NOT send abandon requests for the same operation 
   multiple times, and MUST also be prepared to receive results from 
   operations it has abandoned (since these may have been in transit 
   when the abandon was requested, or are not able to be abandoned). 
    
   Servers MUST discard abandon requests for message IDs they do not 
   recognize, for operations which cannot be abandoned, and for 
   operations which have already been abandoned. 
    
    
4.12. Extended Operation 
    
   An extension mechanism has been added in this version of LDAP, in 
   order to allow additional operations to be defined for services not 
   available elsewhere in this protocol, for instance digitally signed 
   operations and results. 
    
   The extended operation allows clients to make requests and receive 
   responses with predefined syntaxes and semantics. These may be 
   defined in RFCs or be private to particular implementations. Each 
   request MUST have a unique OBJECT IDENTIFIER assigned to it. 
    
        ExtendedRequest ::= [APPLICATION 23] SEQUENCE { 
  
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                requestName      [0] LDAPOID, 
                requestValue     [1] OCTET STRING OPTIONAL } 
    
   The requestName is a dotted-decimal representation of the OBJECT 
   IDENTIFIER corresponding to the request. The requestValue is 
   information in a form defined by that request, encapsulated inside an 
   OCTET STRING. 
    
   The server will respond to this with an LDAPMessage containing the 
   ExtendedResponse. 
    
        ExtendedResponse ::= [APPLICATION 24] SEQUENCE { 
                COMPONENTS OF LDAPResult, 
                responseName     [10] LDAPOID OPTIONAL, 
                response         [11] OCTET STRING OPTIONAL } 
    
   If the server does not recognize the request name, it MUST return 
   only the response fields from LDAPResult, containing the 
   protocolError result code. 
    
4.13. Start TLS Operation 
 
   The Start Transport Layer Security (StartTLS) operation provides the 
   ability to establish Transport Layer Security [RFC2246] on an LDAP 
   connection. 
    
4.13.1. Start TLS Request 
 
   A client requests TLS establishment by transmitting a Start TLS 
   request PDU to the server. The Start TLS request is defined in terms 
   of an ExtendedRequest. The requestName is "1.3.6.1.4.1.1466.20037", 
   and the requestValue field is absent.   
    
   The client MUST NOT send any PDUs on this connection following this 
   request until it receives a Start TLS extended response. 
    
4.13.2. Start TLS Response 
 
   When a Start TLS request is made, servers supporting the operation 
   MUST return a Start TLS response PDU to the requestor.  The Start TLS 
   response responseName is also "1.3.6.1.4.1.1466.20037", and the 
   response field is absent.  
    
   The server MUST set the resultCode field to either success or one of 
   the other values outlined in section 4.13.2.2. 
    
4.13.2.1. "Success" Response 
 
   If the Start TLS Response contains a resultCode of success, this 
   indicates that the server is willing and able to negotiate TLS. Refer 
   to section 5.3 of [AuthMeth] for details. 
    
4.13.2.2. Response other than "success" 
  
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   If the ExtendedResponse contains a resultCode other than success, 
   this indicates that the server is unwilling or unable to negotiate 
   TLS. 
    
   If the Start TLS extended request was not successful, the resultCode 
   will be one of: 
    
   operationsError  (operations sequencing incorrect; e.g. TLS already 
                     established) 
    
   protocolError    (TLS not supported or incorrect PDU structure) 
    
   referral         (this server doesn't do TLS, try this one) 
    
   unavailable      (e.g. some major problem with TLS, or server is  
                     shutting down) 
    
   The server MUST return operationsError if the client violates any of 
   the Start TLS extended operation sequencing requirements described in 
   section 5.3 of [AuthMeth]. 
    
   If the server does not support TLS (whether by design or by current 
   configuration), it MUST set the resultCode to protocolError, or to 
   referral. The server MUST include an actual referral value in the 
   LDAP Result if it returns a resultCode of referral. The client's 
   current session is unaffected if the server does not support TLS. The 
   client MAY proceed with any LDAP operation, or it MAY close the 
   connection. 
    
   The server MUST return unavailable if it supports TLS but cannot 
   establish a TLS connection for some reason, e.g. the certificate 
   server not responding, it cannot contact its TLS implementation, or 
   if the server is in process of shutting down. The client MAY retry 
   the StartTLS operation, or it MAY proceed with any other LDAP 
   operation, or it MAY close the connection. 
 
4.13.3. Closing a TLS Connection 
 
   Two forms of TLS connection closure--graceful and abrupt--are 
   supported. 
    
4.13.3.1. Graceful Closure 
 
   Either the client or server MAY terminate the TLS connection and 
   leave the LDAP session intact by sending a TLS closure alert. 
    
   Before sending a TLS closure alert, the client MUST either wait for 
   any outstanding LDAP operations to complete, or explicitly abandon 
   them.  
    
   After the initiator of a close has sent a TLS closure alert, it MUST 
   discard any TLS messages until it has received a TLS closure alert 
  
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   from the other party.  It will cease to send TLS Record Protocol 
   PDUs, and following the receipt of the alert, MAY send and receive 
   LDAP PDUs. 
    
   The other party, if it receives a TLS closure alert, MUST immediately 
   transmit a TLS closure alert.  It will subsequently cease to send TLS 
   Record Protocol PDUs, and MAY send and receive LDAP PDUs. 
    
4.13.3.2. Abrupt Closure 
 
   Either the client or server MAY abruptly close the TLS connection by 
   dropping the underlying transfer protocol connection. In this 
   circumstance, a server MAY send the client a Notice of Disconnection 
   before dropping the underlying connection. 
    
    
5. Protocol Element Encodings and Transfer 
    
   One underlying service is defined here. Clients and servers SHOULD 
   implement the mapping of LDAP over TCP described in 5.2.1. 
    
    
5.1. Protocol Encoding 
    
   The protocol elements of LDAP are encoded for exchange using the 
   Basic Encoding Rules (BER) [X.690] of ASN.1 [X.680]. However, due to 
   the high overhead involved in using certain elements of the BER, the 
   following additional restrictions are placed on BER-encodings of LDAP 
   protocol elements: 
    
   (1) Only the definite form of length encoding will be used. 
    
   (2) OCTET STRING values will be encoded in the primitive form only. 
    
   (3) If the value of a BOOLEAN type is true, the encoding MUST have 
       its contents octets set to hex "FF". 
    
   (4) If a value of a type is its default value, it MUST be absent. 
       Only some BOOLEAN and INTEGER types have default values in this 
       protocol definition. 
    
   These restrictions do not apply to ASN.1 types encapsulated inside of 
   OCTET STRING values, such as attribute values, unless otherwise 
   noted. 
    
    
5.2. Transfer Protocols 
    
   This protocol is designed to run over connection-oriented, reliable 
   transports, with all 8 bits in an octet being significant in the data 
   stream. 
    
    
  
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5.2.1. Transmission Control Protocol (TCP) 
    
   The encoded LDAPMessage PDUs are mapped directly onto the TCP 
   bytestream using the BER-based encoding described in section 5.1. It 
   is recommended that server implementations running over the TCP 
   provide a protocol listener on the assigned port, 389. Servers may 
   instead provide a listener on a different port number. Clients MUST 
   support contacting servers on any valid TCP port. 
    
    
6. Implementation Guidelines 
    
    
6.1. Server Implementations 
    
   The server MUST be capable of recognizing all the mandatory attribute 
   type names and implement the syntaxes specified in [Syntaxes]. 
   Servers MAY also recognize additional attribute type names. 
    
    
6.2. Client Implementations 
    
   Clients that follow referrals or search continuation references MUST 
   ensure that they do not loop between servers. They MUST NOT 
   repeatedly contact the same server for the same request with the same 
   target entry name, scope and filter. Some clients use a counter that 
   is incremented each time referral handling occurs for an operation, 
   and these kinds of clients MUST be able to handle a DIT with at least 
   ten layers of naming contexts between the root and a leaf entry. 
    
   In the absence of prior agreements with servers, clients SHOULD NOT 
   assume that servers support any particular schemas beyond those 
   referenced in section 6.1. Different schemas can have different 
   attribute types with the same names. The client can retrieve the 
   subschema entries referenced by the subschemaSubentry attribute in 
   the entries held by the server. 
    
    
7. Security Considerations 
    
   When used with a connection-oriented transport, this version of the 
   protocol provides facilities for simple authentication using a 
   cleartext password, as well as any SASL mechanism [RFC2222]. SASL 
   allows for integrity and privacy services to be negotiated. 
    
   It is also permitted that the server can return its credentials to 
   the client, if it chooses to do so. 
    
   Use of cleartext password is strongly discouraged where the 
   underlying transport service cannot guarantee confidentiality and may 
   result in disclosure of the password to unauthorized parties. 
    
   When used with SASL, it should be noted that the name field of the 
   BindRequest is not protected against modification. Thus if the 
  
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   distinguished name of the client (an LDAPDN) is agreed through the 
   negotiation of the credentials, it takes precedence over any value in 
   the unprotected name field. 
    
   Implementations which cache attributes and entries obtained via LDAP 
   MUST ensure that access controls are maintained if that information 
   is to be provided to multiple clients, since servers may have access 
   control policies which prevent the return of entries or attributes in 
   search results except to particular authenticated clients. For 
   example, caches could serve result information only to the client 
   whose request caused it to be in the cache. 
    
   Protocol servers may return referrals which redirect protocol clients 
   to peer servers. It is possible for a rogue application to inject 
   such referrals into the data stream in an attempt to redirect a 
   client to a rogue server. Protocol clients are advised to be aware of 
   this, and possibly reject referrals when confidentiality measures are 
   in place. Protocol clients are advised to ignore referrals from the 
   Start TLS operation. 
    
    
8. Acknowledgements 
    
   This document is an update to RFC 2251, by Mark Wahl, Tim Howes, and 
   Steve Kille. Their work along with the input of individuals of the 
   IETF LDAPEXT, LDUP, LDAPBIS, and other Working Groups is gratefully 
   acknowledged. 
    
    
9. Normative References 
 
   [X.500]   ITU-T Rec. X.500, "The Directory: Overview of Concepts, 
             Models and Service", 1993.  
    
   [Roadmap] K. Zeilenga (editor), "LDAP: Technical Specification Road 
             Map", draft-ietf-ldapbis-roadmap-xx.txt (a work in 
             progress). 
    
   [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 
             Requirement Levels", RFC 2119, March 1997. 
     
   [X.680]   ITU-T Recommendation X.680 (1997) | ISO/IEC 8824-1:1998 
             Information Technology - Abstract Syntax Notation One 
             (ASN.1): Specification of basic notation 
    
   [X.690]   ITU-T Rec. X.690, "Specification of ASN.1 encoding rules: 
             Basic, Canonical, and Distinguished Encoding Rules", 1994. 
    
   [LDAPIANA] K. Zeilenga, "IANA Considerations for LDAP", draft-ietf-
             ldapbis-xx.txt (a work in progress). 
    
   [ISO10646] Universal Multiple-Octet Coded Character Set (UCS) - 
             Architecture and Basic Multilingual Plane, ISO/IEC 10646-1 
             : 1993. 
  
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   [RFC2279] Yergeau, F., "UTF-8, a transformation format of Unicode 
             and ISO 10646", RFC 2279, January 1998. 
    
   [Models]  K. Zeilenga, "LDAP: The Models", draft-ietf-ldapbis-
             models-xx.txt (a work in progress). 
    
   [LDAPDN]  K. Zeilenga (editor), "LDAP: String Representation of 
             Distinguished Names", draft-ietf-ldapbis-dn-xx.txt, (a 
             work in progress). 
    
   [Syntaxes] K. Dally (editor), "LDAP: Syntaxes", draft-ietf-ldapbis-
             syntaxes-xx.txt, (a work in progress). 
    
   [X.501]   ITU-T Rec. X.501, "The Directory: Models", 1993. 
    
   [X.511]   ITU-T Rec. X.511, "The Directory: Abstract Service 
             Definition", 1993. 
    
   [RFC2396] Berners-Lee, T., Fielding, R., and L. Masinter Uniform 
             Resource Identifiers (URI): Generic Syntax", RFC 2396, 
             August 1998. 
    
   [AuthMeth] R. Harrison (editor), "LDAP: Authentication Methods", 
             draft-ietf-ldapbis-authmeth-xx.txt, (a work in progress). 
    
   [RFC2222] Meyers, J., "Simple Authentication and Security Layer", 
             RFC 2222, October 1997. 
 
 
10. Editor's Address 
    
   Jim Sermersheim 
   Novell, Inc. 
   1800 South Novell Place 
   Provo, Utah 84606, USA 
   jimse@novell.com 
   +1 801 861-3088 
















  
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Appendix A - LDAP Result Codes 
 
   This normative appendix details additional considerations regarding 
   LDAP result codes and provides a brief, general description of each 
   LDAP result code enumerated in Section 4.1.10. 
    
   Additional result codes MAY be defined for use with extensions. 
   Client implementations SHALL treat any result code which they do not 
   recognize as an unknown error condition. 
    
A.1 Non-Error Result Codes 
   These result codes (called "non-error" result codes) do not indicate 
   an error condition: 
        success(0), 
        compareTrue(6), 
        compareFalse(7), 
        referral(10), and 
        saslBindInProgress(14). 
    
   The success(0), compareTrue(6), and compare(7) result codes indicate 
   successful completion (and, hence, are called to as "successful" 
   result codes). 
    
   The referral(10) and saslBindInProgress(14) indicate the client is 
   required to take additional action to complete the operation 
    
    
A.2 Error Result Codes 
    
A.3 Classes and Precedence of Error Result Codes 
    
   Result codes that indicate error conditions (and, hence, are called 
   "error" result codes) fall into 6 classes. The following list 
   specifies the precedence of error classes to be used when more than 
   one error is detected [X511]: 
        1) Name Errors (codes 32 - 34, 36)  
                - a problem related to a name (DN or RDN), 
        2) Update Errors (codes 64 - 69, 71) 
                - a problem related to an update operation, 
        3) Attribute Errors (codes 16 - 21) 
                - a problem related to a supplied attribute, 
        4) Security Errors (codes 8, 13, 48 - 50) 
                - a security related problem, 
        5) Service Problem (codes 3, 4, 7, 11, 12, 51 - 54, 80) 
                - a problem related to the provision of the service, and 
        6) Protocol Problem (codes 1, 2) 
                - a problem related to protocol structure or semantics. 
    
   If the server detects multiple errors simultaneously, the server 
   SHOULD report the error with the highest precedence. 
    
   Existing LDAP result codes are described as follows: 
 
        success (0) 
  
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           Indicates successful completion of an operation. 
    
           This result code is normally not returned by the compare 
           operation, see compareFalse (5) and compareTrue (6). It is 
           possible that a future extension mechanism would allow this 
           to be returned by a compare operation. 
    
    
        operationsError (1) 
    
           Indicates that the operation is not properly sequenced with 
           relation to other operations (of same or different type). 
 
           For example, this code is returned if the client attempts to 
           Start TLS [RFC2246] while there are other operations 
           outstanding or if TLS was already established. 
            
 
 
        protocolError (2) 
 
           Indicates the server received data which has incorrect 
           structure. 
            
           For bind operation only, the code may be resulted to indicate 
           the server does not support the requested protocol version. 
            
 
        timeLimitExceeded (3) 
         
           Indicates that the time limit specified by the client was 
           exceeded before the operation could be completed. 
         
         
        sizeLimitExceeded (4) 
         
           Indicates that the size limit specified by the client was 
           exceeded before the operation could be completed. 
         
         
        compareFalse (5) 
         
           Indicates that the operation successfully completes and the 
           assertion has evaluated to FALSE. 
         
           This result code is normally only returned by the compare 
           operation. 
         
         
        compareTrue (6) 
         
           Indicates that the operation successfully completes and the 
           assertion has evaluated to TRUE. 
  
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           This result code is normally only returned by the compare 
           operation. 
         
         
        authMethodNotSupported (7) 
         
           Indicates that the authentication method or mechanism is not 
           supported. 
         
         
        strongAuthRequired (8) 
         
           Except when returned in a Notice of Disconnect (see section 
           4.4.1), this indicates that the server requires the client to 
           authentication using a strong(er) mechanism. 
         
         
        referral (10) 
         
           Indicates that a referral needs to be chased to complete the 
           operation (see section 4.1.11). 
         
         
        adminLimitExceeded (11) 
         
           Indicates that an administrative limit has been exceeded. 
         
         
        unavailableCriticalExtension (12) 
         
           Indicates that server cannot perform a critical extension 
           (see section 4.1.12). 
         
         
        confidentialityRequired (13) 
         
           Indicates that data confidentiality protections are required. 
         
         
        saslBindInProgress (14) 
         
           Indicates the server requires the client to send a new bind 
           request, with the same SASL mechanism, to continue the 
           authentication process (see section 4.2). 
         
         
        noSuchAttribute (16) 
         
           Indicates that the named entry does not contain the specified 
           attribute or attribute value. 
         
         
        undefinedAttributeType (17) 
  
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           Indicates that a request field contains an undefined 
           attribute type. 
         
         
        inappropriateMatching (18) 
         
           Indicates that a request cannot be completed due to an 
           inappropriate matching. 
         
         
        constraintViolation (19) 
         
           Indicates that the client supplied an attribute value which 
           does not conform to constraints placed upon it by the data 
           model. 
         
           For example, this code is returned when the multiple values 
           are supplied to an attribute which has a SINGLE-VALUE 
           constraint. 
         
         
        attributeOrValueExists (20) 
         
           Indicates that the client supplied an attribute or value to 
           be added to an entry already exists. 
         
         
        invalidAttributeSyntax (21) 
         
           Indicates that a purported attribute value does not conform 
           to the syntax of the attribute. 
         
         
        noSuchObject (32) 
         
           Indicates that the object does not exist in the DIT. 
         
         
        aliasProblem (33) 
         
           Indicates that an alias problem has occurred. Typically an 
           alias has been dereferenced which names no object. 
         
         
        invalidDNSyntax (34) 
         
           Indicates that a LDAPDN or RelativeLDAPDN field (e.g. search 
           base, target entry, ModifyDN newrdn, etc.) of a request does 
           not conform to the required syntax or contains attribute 
           values which do not conform to the syntax of the attribute's 
           type. 
         
         
  
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        aliasDereferencingProblem (36) 
         
           Indicates that a problem occurred while dereferencing an 
           alias. Typically an alias was encountered in a situation 
           where it was not allowed or where access was denied. 
         
         
        inappropriateAuthentication (48) 
         
           Indicates the server requires the client which had attempted 
           to bind anonymously or without supplying credentials to 
           provide some form of credentials, 
         
         
        invalidCredentials (49) 
         
           Indicates the supplied password or SASL credentials are 
           invalid. 
         
         
        insufficientAccessRights (50) 
         
           Indicates that the client does not have sufficient access 
           rights to perform the operation. 
         
         
        busy (51) 
         
           Indicates that the server is busy. 
         
         
        unavailable (52) 
         
           Indicates that the server is shutting down or a subsystem 
           necessary to complete the operation is offline. 
         
         
        unwillingToPerform (53) 
         
           Indicates that the server is unwilling to perform the 
           operation. 
         
         
        loopDetect (54) 
         
           Indicates that the server has detected an internal loop. 
         
         
        namingViolation (64) 
         
           Indicates that the entry name violates naming restrictions. 
         
        objectClassViolation (65) 
         
  
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           Indicates that the entry violates object class restrictions. 
         
         
        notAllowedOnNonLeaf (66) 
         
           Indicates that operation is inappropriately acting upon a 
           non-leaf entry. 
         
         
        notAllowedOnRDN (67) 
         
           Indicates that the operation is inappropriately attempting to 
           remove a value which forms the entry's relative distinguished 
           name. 
         
         
        entryAlreadyExists (68) 
         
           Indicates that the request cannot be added fulfilled as the 
           entry already exists. 
         
         
        objectClassModsProhibited (69) 
         
           Indicates that the attempt to modify the object class(es) of 
           an entry objectClass attribute is prohibited. 
         
           For example, this code is returned when a when a client 
           attempts to modify the structural object class of an entry. 
         
         
        affectsMultipleDSAs (71) 
         
           Indicates that the operation cannot be completed as it 
           affects multiple servers (DSAs). 
         
         
        other (80) 
         
           Indicates the server has encountered an internal error. 














  
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   Appendix B - Complete ASN.1 Definition 
    
        This appendix is normative. 
    
        Lightweight-Directory-Access-Protocol-V3 DEFINITIONS 
        IMPLICIT TAGS 
        EXTENSIBILITY IMPLIED ::= 
    
        BEGIN 
    
        LDAPMessage ::= SEQUENCE { 
                messageID       MessageID, 
                protocolOp      CHOICE { 
                        bindRequest     BindRequest, 
                        bindResponse    BindResponse, 
                        unbindRequest   UnbindRequest, 
                        searchRequest   SearchRequest, 
                        searchResEntry  SearchResultEntry, 
                        searchResDone   SearchResultDone, 
                        searchResRef    SearchResultReference, 
                        modifyRequest   ModifyRequest, 
                        modifyResponse  ModifyResponse, 
                        addRequest      AddRequest, 
                        addResponse     AddResponse, 
                        delRequest      DelRequest, 
                        delResponse     DelResponse, 
                        modDNRequest    ModifyDNRequest, 
                        modDNResponse   ModifyDNResponse, 
                        compareRequest  CompareRequest, 
                        compareResponse CompareResponse, 
                        abandonRequest  AbandonRequest, 
                        extendedReq     ExtendedRequest, 
                        extendedResp    ExtendedResponse, 
                        ... }, 
                 controls       [0] Controls OPTIONAL } 
    
        MessageID ::= INTEGER (0 .. maxInt) 
    
        maxInt INTEGER ::= 2147483647 -- (2^^31 - 1) -- 
    
        LDAPString ::= OCTET STRING -- UTF-8 encoded, 
                                    -- [ISO10646] characters 
    
        LDAPOID ::= OCTET STRING -- Constrained to numericoid [Models] 
    
        LDAPDN ::= LDAPString 
    
        RelativeLDAPDN ::= LDAPString 
    
        AttributeDescription ::= LDAPString 
                                 -- Constrained to attributedescription 
                                 -- [Models] 
    
        AttributeDescriptionList ::= SEQUENCE OF 
  
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                AttributeDescription 
    
        AttributeValue ::= OCTET STRING 
    
        AttributeValueAssertion ::= SEQUENCE { 
                attributeDesc   AttributeDescription, 
                assertionValue  AssertionValue } 
    
        AssertionValue ::= OCTET STRING 
    
        Attribute ::= SEQUENCE { 
                type    AttributeDescription, 
                vals    SET OF AttributeValue } 
    
        MatchingRuleId ::= LDAPString 
    
        LDAPResult ::= SEQUENCE { 
                resultCode         ENUMERATED { 
                             success                      (0), 
                             operationsError              (1), 
                             protocolError                (2), 
                             timeLimitExceeded            (3), 
                             sizeLimitExceeded            (4), 
                             compareFalse                 (5), 
                             compareTrue                  (6), 
                             authMethodNotSupported       (7), 
                             strongAuthRequired           (8), 
                                        -- 9 reserved -- 
                             referral                     (10), 
                             adminLimitExceeded           (11), 
                             unavailableCriticalExtension (12), 
                             confidentialityRequired      (13), 
                             saslBindInProgress           (14), 
                             noSuchAttribute              (16), 
                             undefinedAttributeType       (17), 
                             inappropriateMatching        (18), 
                             constraintViolation          (19), 
                             attributeOrValueExists       (20), 
                             invalidAttributeSyntax       (21), 
                                        -- 22-31 unused -- 
                             noSuchObject                 (32), 
                             aliasProblem                 (33), 
                             invalidDNSyntax              (34), 
                             -- 35 reserved for undefined isLeaf -- 
                             aliasDereferencingProblem    (36), 
                                        -- 37-47 unused -- 
                             inappropriateAuthentication  (48), 
                             invalidCredentials           (49), 
                             insufficientAccessRights     (50), 
                             busy                         (51), 
                             unavailable                  (52), 
                             unwillingToPerform           (53), 
                             loopDetect                   (54), 
                                        -- 55-63 unused -- 
  
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                             namingViolation              (64), 
                             objectClassViolation         (65), 
                             notAllowedOnNonLeaf          (66), 
                             notAllowedOnRDN              (67), 
                             entryAlreadyExists           (68), 
                             objectClassModsProhibited    (69), 
                                        -- 70 reserved for CLDAP -- 
                             affectsMultipleDSAs          (71), 
                                        -- 72-79 unused -- 
                             other                        (80), 
                             ... }, 
                             -- 81-90 reserved for APIs -- 
                matchedDN          LDAPDN, 
                diagnosticMessage  LDAPString, 
                referral           [3] Referral OPTIONAL } 
    
        Referral ::= SEQUENCE OF LDAPURL 
    
        LDAPURL ::= LDAPString -- limited to characters permitted in 
                               -- URLs 
    
        Controls ::= SEQUENCE OF Control 
    
        Control ::= SEQUENCE { 
                controlType             LDAPOID, 
                criticality             BOOLEAN DEFAULT FALSE, 
                controlValue            OCTET STRING OPTIONAL } 
    
        BindRequest ::= [APPLICATION 0] SEQUENCE { 
                version                 INTEGER (1 .. 127), 
                name                    LDAPDN, 
                authentication          AuthenticationChoice } 
    
        AuthenticationChoice ::= CHOICE { 
                simple                  [0] OCTET STRING, 
                                         -- 1 and 2 reserved 
                sasl                    [3] SaslCredentials, 
                ... } 
    
        SaslCredentials ::= SEQUENCE { 
                mechanism               LDAPString, 
                credentials             OCTET STRING OPTIONAL } 
    
        BindResponse ::= [APPLICATION 1] SEQUENCE { 
             COMPONENTS OF LDAPResult, 
             serverSaslCreds    [7] OCTET STRING OPTIONAL } 
    
        UnbindRequest ::= [APPLICATION 2] NULL 
    
        SearchRequest ::= [APPLICATION 3] SEQUENCE { 
                baseObject      LDAPDN, 
                scope           ENUMERATED { 
                        baseObject              (0), 
                        singleLevel             (1), 
  
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                        wholeSubtree            (2) }, 
                derefAliases    ENUMERATED { 
                        neverDerefAliases       (0), 
                        derefInSearching        (1), 
                        derefFindingBaseObj     (2), 
                        derefAlways             (3) }, 
                sizeLimit       INTEGER (0 .. maxInt), 
                timeLimit       INTEGER (0 .. maxInt), 
                typesOnly       BOOLEAN, 
                filter          Filter, 
                attributes      AttributeDescriptionList } 
    
        Filter ::= CHOICE { 
                and             [0] SET SIZE (1..MAX) OF Filter, 
                or              [1] SET SIZE (1..MAX) OF Filter, 
                not             [2] Filter, 
                equalityMatch   [3] AttributeValueAssertion, 
                substrings      [4] SubstringFilter, 
                greaterOrEqual  [5] AttributeValueAssertion, 
                lessOrEqual     [6] AttributeValueAssertion, 
                present         [7] AttributeDescription, 
                approxMatch     [8] AttributeValueAssertion, 
                extensibleMatch [9] MatchingRuleAssertion } 
    
        SubstringFilter ::= SEQUENCE { 
                type            AttributeDescription, 
                -- at least one must be present, 
                -- initial and final can occur at most once 
                substrings      SEQUENCE OF CHOICE { 
                        initial [0] AssertionValue, 
                        any     [1] AssertionValue, 
                        final   [2] AssertionValue } } 
    
        MatchingRuleAssertion ::= SEQUENCE { 
                matchingRule    [1] MatchingRuleId OPTIONAL, 
                type            [2] AttributeDescription OPTIONAL, 
                matchValue      [3] AssertionValue, 
                dnAttributes    [4] BOOLEAN DEFAULT FALSE } 
    
        SearchResultEntry ::= [APPLICATION 4] SEQUENCE { 
                objectName      LDAPDN, 
                attributes      PartialAttributeList } 
    
        PartialAttributeList ::= SEQUENCE OF SEQUENCE { 
                type    AttributeDescription, 
                vals    SET OF AttributeValue } 
    
        SearchResultReference ::= [APPLICATION 19] SEQUENCE OF LDAPURL 
    
        SearchResultDone ::= [APPLICATION 5] LDAPResult 
    
        ModifyRequest ::= [APPLICATION 6] SEQUENCE { 
                object          LDAPDN, 
                modification    SEQUENCE OF SEQUENCE { 
  
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                        operation       ENUMERATED { 
                                                add     (0), 
                                                delete  (1), 
                                                replace (2) }, 
                        modification    AttributeTypeAndValues } } 
    
        AttributeTypeAndValues ::= SEQUENCE { 
                type    AttributeDescription, 
                vals    SET OF AttributeValue } 
    
        ModifyResponse ::= [APPLICATION 7] LDAPResult 
    
        AddRequest ::= [APPLICATION 8] SEQUENCE { 
                entry           LDAPDN, 
                attributes      AttributeList } 
    
        AttributeList ::= SEQUENCE OF SEQUENCE { 
                type    AttributeDescription, 
                vals    SET OF AttributeValue } 
    
        AddResponse ::= [APPLICATION 9] LDAPResult 
    
        DelRequest ::= [APPLICATION 10] LDAPDN 
    
        DelResponse ::= [APPLICATION 11] LDAPResult 
    
        ModifyDNRequest ::= [APPLICATION 12] SEQUENCE { 
                entry           LDAPDN, 
                newrdn          RelativeLDAPDN, 
                deleteoldrdn    BOOLEAN, 
                newSuperior     [0] LDAPDN OPTIONAL } 
    
        ModifyDNResponse ::= [APPLICATION 13] LDAPResult 
    
        CompareRequest ::= [APPLICATION 14] SEQUENCE { 
                entry           LDAPDN, 
                ava             AttributeValueAssertion } 
    
        CompareResponse ::= [APPLICATION 15] LDAPResult 
    
        AbandonRequest ::= [APPLICATION 16] MessageID 
    
        ExtendedRequest ::= [APPLICATION 23] SEQUENCE { 
                requestName      [0] LDAPOID, 
                requestValue     [1] OCTET STRING OPTIONAL } 
    
        ExtendedResponse ::= [APPLICATION 24] SEQUENCE { 
                COMPONENTS OF LDAPResult, 
                responseName     [10] LDAPOID OPTIONAL, 
                response         [11] OCTET STRING OPTIONAL } 
    
        END 


  
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Appendix C - Change History 
   <Note to RFC editor: This section is to be removed prior to RFC 
   publication> 
    
C.1 Changes made to RFC 2251: 
 
C.1.1 Editorial 
    
   - Bibliography References: Changed all bibliography references to 
     use a long name form for readability. 
   - Changed occurrences of "unsupportedCriticalExtension" 
     "unavailableCriticalExtension" 
   - Fixed a small number of misspellings (mostly dropped letters). 
    
C.1.2 Section 1 
    
   - Removed IESG note. 
    
C.1.3 Section 9 
    
   - Added references to RFCs 1823, 2234, 2829 and 2830. 
    
 
C.2 Changes made to draft-ietf-ldapbis-protocol-00.txt: 
    
C.2.1 Section 4.1.6 
    
   - In the first paragraph, clarified what the contents of an 
     AttributeValue are. There was confusion regarding whether or not 
     an AttributeValue that is BER encoded (due to the "binary" option) 
     is to be wrapped in an extra OCTET STRING. 
   - To the first paragraph, added wording that doesn't restrict other 
     transfer encoding specifiers from being used. The previous wording 
     only allowed for the string encoding and the ;binary encoding. 
   - To the first paragraph, added a statement restricting multiple 
     options that specify transfer encoding from being present. This 
     was never specified in the previous version and was seen as a 
     potential interoperability problem. 
   - Added a third paragraph stating that the ;binary option is 
     currently the only option defined that specifies the transfer 
     encoding. This is for completeness. 
    
C.2.2 Section 4.1.7 
    
   - Generalized the second paragraph to read "If an option specifying 
     the transfer encoding is present in attributeDesc, the 
     AssertionValue is encoded as specified by the option...". 
     Previously, only the ;binary option was mentioned. 
    
C.2.3 Sections 4.2, 4.9, 4.10 
    
   - Added alias dereferencing specifications. In the case of modDN, 
     followed precedent set on other update operations (... alias is 
     not dereferenced...) In the case of bind and compare stated that 
  
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     servers SHOULD NOT dereference aliases. Specifications were added 
     because they were missing from the previous version and caused 
     interoperability problems. Concessions were made for bind and 
     compare (neither should have ever allowed alias dereferencing) by 
     using SHOULD NOT language, due to the behavior of some existing 
     implementations. 
    
C.2.4 Sections 4.5 and Appendix A 
    
   - Changed SubstringFilter.substrings.initial, any, and all from 
     LDAPString to AssertionValue. This was causing an incompatibility 
     with X.500 and confusion among other TS RFCs.  
    
 
C.3 Changes made to draft-ietf-ldapbis-protocol-01.txt: 
 
C.3.1 Section 3.4 
    
   - Reworded text surrounding subschemaSubentry to reflect that it is 
     a single-valued attribute that holds the schema for the root DSE. 
     Also noted that if the server masters entries that use differing 
     schema, each entry's subschemaSubentry attribute must be 
     interrogated. This may change as further fine-tuning is done to 
     the data model. 
    
C.3.2 Section 4.1.12 
    
   - Specified that the criticality field is only used for requests and 
     not for unbind or abandon. Noted that it is ignored for all other 
     operations. 
    
C.3.3 Section 4.2 
    
   - Noted that Server behavior is undefined when the name is a null 
     value, simple authentication is used, and a password is specified. 
    
C.3.4 Section 4.2.(various) 
    
   - Changed "unauthenticated" to "anonymous" and "DN" and "LDAPDN" to 
     "name" 
    
C.3.5 Section 4.2.2 
    
   - Changed "there is no authentication or encryption being performed 
     by a lower layer" to "the underlying transport service cannot 
     guarantee confidentiality" 
    
C.3.6 Section 4.5.2 
    
   - Removed all mention of ExtendedResponse due to lack of 
     implementation. 
    
C.4 Changes made to draft-ietf-ldapbis-protocol-02.txt: 
 
  
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C.4.1 Section 4 
    
   - Removed "typically" from "and is typically transferred" in the 
     first paragraph. We know of no (and can conceive of no) case where 
     this isn't true. 
   - Added "Section 5.1 specifies how the LDAP protocol is encoded." To 
     the first paragraph. Added this cross reference for readability. 
   - Changed "version 3 " to "version 3 or later" in the second 
     paragraph. This was added to clarify the original intent. 
   - Changed "protocol version" to "protocol versions" in the third 
     paragraph. This attribute is multi-valued with the intent of 
     holding all supported versions, not just one. 
 
C.4.2 Section 4.1.8 
    
   - Changed "when transferred in protocol" to "when transferred from 
     the server to the client" in the first paragraph. This is to 
     clarify that this behavior only happens when attributes are being 
     sent from the server. 
    
C.4.3 Section 4.1.10 
 
   - Changed "servers will return responses containing fields of type 
     LDAPResult" to "servers will return responses of LDAPResult or 
     responses containing the components of LDAPResponse". This 
     statement was incorrect and at odds with the ASN.1. The fix here 
     reflects the original intent. 
   - Dropped '--new' from result codes ASN.1. This simplification in 
     comments just reduces unneeded verbiage. 
 
C.4.4 Section 4.1.11 
    
   - Changed "It contains a reference to another server (or set of 
     servers)" to "It contains one or more references to one or more 
     servers or services" in the first paragraph. This reflects the 
     original intent and clarifies that the URL may point to non-LDAP 
     services. 
    
C.4.5 Section 4.1.12 
    
   - Changed "The server MUST be prepared" to "Implementations MUST be 
     prepared" in the eighth paragraph to reflect that both client and 
     server implementations must be able to handle this (as both parse 
     controls). 
    
C.4.6 Section 4.4 
    
   - Changed "One unsolicited notification is defined" to "One 
     unsolicited notification (Notice of Disconnection) is defined" in 
     the third paragraph. For clarity and readability. 
 
C.4.7 Section 4.5.1 
    

  
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   - Changed "checking for the existence of the objectClass attribute" 
     to "checking for the presence of the objectClass attribute" in the 
     last paragraph. This was done as a measure of consistency (we use 
     the terms present and presence rather than exists and existence in 
     search filters). 
 
C.4.8 Section 4.5.3 
    
   - Changed "outstanding search operations to different servers," to 
     "outstanding search operations" in the fifth paragraph as they may 
     be to the same server. This is a point of clarification. 
 
C.4.9 Section 4.6 
    
   - Changed "clients MUST NOT attempt to delete" to "clients MUST NOT 
     attempt to add or delete" in the second to last paragraph. 
   - Change "using the "delete" form" to "using the "add" or "delete" 
     form" in the second to last paragraph. 
 
C.4.10 Section 4.7 
    
   - Changed "Clients MUST NOT supply the createTimestamp or 
     creatorsName attributes, since these will be generated 
     automatically by the server." to "Clients MUST NOT supply NO-USER-
     MODIFICATION attributes such as createTimestamp or creatorsName 
     attributes, since these are provided by the server." in the 
     definition of the attributes field. This tightens the language to 
     reflect the original intent and to not leave a hole in which one 
     could interpret the two attributes mentioned as the only non-
     writable attributes. 
 
C.4.11 Section 4.11 
    
   - Changed "has been" to "will be" in the fourth paragraph. This 
     clarifies that the server will (not has) abandon the operation. 
    
 
C.5 Changes made to draft-ietf-ldapbis-protocol-03.txt: 
    
C.5.1 Section 3.2.1 
    
   - Changed "An attribute is a type with one or more associated 
     values. The attribute type is identified by a short descriptive 
     name and an OID (object identifier). The attribute type governs 
     whether there can be more than one value of an attribute of that 
     type in an entry, the syntax to which the values must conform, the 
     kinds of matching which can be performed on values of that 
     attribute, and other functions." to " An attribute is a 
     description (a type and zero or more options) with one or more 
     associated values. The attribute type governs whether the 
     attribute can have multiple values, the syntax and matching rules 
     used to construct and compare values of that attribute, and other 
     functions. Options indicate modes of transfer and other 

  
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     functions.". This points out that an attribute consists of both 
     the type and options. 
    
C.5.2 Section 4 
    
   -  Changed "Section 5.1 specifies the encoding rules for the LDAP 
     protocol" to "Section 5.1 specifies how the protocol is encoded 
     and transferred." 
 
C.5.3 Section 4.1.2 
    
   - Added ABNF for the textual representation of LDAPOID. Previously, 
     there was no formal BNF for this construct. 
    
C.5.4 Section 4.1.4 
 
   - Changed "This identifier may be written as decimal digits with 
     components separated by periods, e.g. "2.5.4.10"" to "may be 
     written as defined by ldapOID in section 4.1.2" in the second 
     paragraph. This was done because we now have a formal BNF 
     definition of an oid. 
    
C.5.5 Section 4.1.5 
    
   - Changed the BNF for AttributeDescription to ABNF. This was done 
     for readability and consistency (no functional changes involved). 
   - Changed "Options present in an AttributeDescription are never 
     mutually exclusive." to "Options MAY be mutually exclusive. An 
     AttributeDescription with mutually exclusive options is treated as 
     an undefined attribute type." for clarity. It is generally 
     understood that this is the original intent, but the wording could 
     be easily misinterpreted. 
   - Changed "Any option could be associated with any AttributeType, 
     although not all combinations may be supported by a server." to 
     "Though any option or set of options could be associated with any 
     AttributeType, the server support for certain combinations may be 
     restricted by attribute type, syntaxes, or other factors.". This 
     is to clarify the meaning of 'combination' (it applies both to 
     combination of attribute type and options, and combination of 
     options). It also gives examples of *why* they might be 
     unsupported. 
    
C.5.6 Section 4.1.11 
    
   - Changed the wording regarding 'equally capable' referrals to "If 
     multiple URLs are present, the client assumes that any URL may be 
     used to progress the operation.". The previous language implied 
     that the server MUST enforce rules that it was practically 
     incapable of. The new language highlights the original intent--
     that is, that any of the referrals may be used to progress the 
     operation, there is no inherent 'weighting' mechanism.  
    
C.5.7 Section 4.5.1 and Appendix A 
    
  
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   - Added the comment "-- initial and final can occur at most once", 
     to clarify this restriction. 
    
C.5.8 Section 5.1 
    
   - Changed heading from "Mapping Onto BER-based Transport Services" 
     to "Protocol Encoding". 
    
C.5.9 Section 5.2.1 
    
   - Changed "The LDAPMessage PDUs" to "The encoded LDAPMessage PDUs" 
     to point out that the PDUs are encoded before being streamed to 
     TCP. 
    
C.6 Changes made to draft-ietf-ldapbis-protocol-04.txt: 
    
C.6.1 Section 4.5.1 and Appendix A 
 
   - Changed the ASN.1 for the and and or choices of Filter to have a 
     lower range of 1. This was an omission in the original ASN.1  
    
C.6.2 Various 
    
   - Fixed various typo's 
 
C.7 Changes made to draft-ietf-ldapbis-protocol-05.txt: 
    
C.7.1 Section 3.2.1 
 
   - Added "(as defined in Section 12.4.1 of [X.501])" to the fifth 
     paragraph when talking about "operational attributes". This is 
     because the term "operational attributes" is never defined. 
     Alternately, we could drag a definition into the spec, for now, 
     I'm just pointing to the reference in X.501. 
    
C.7.2 Section 4.1.5 
    
   - Changed "And is also case insensitive" to "The entire 
     AttributeDescription is case insensitive". This is to clarify 
     whether we're talking about the entire attribute description, or 
     just the options. 
    
   - Expounded on the definition of attribute description options. This 
     doc now specifies a difference between transfer and tagging 
     options and describes the semantics of each, and how and when 
     subtyping rules apply. Now allow options to be transmitted in any 
     order but disallow any ordering semantics to be implied. These 
     changes are the result of ongoing input from an engineering team 
     designed to deal with ambiguity issues surrounding attribute 
     options. 
    
C.7.3 Sections 4.1.5.1 and 4.1.6 
    

  
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   - Refer to non "binary" transfer encodings as "native encoding" 
     rather than "string" encoding to clarify and avoid confusion. 
    
C.8 Changes made to draft-ietf-ldapbis-protocol-06.txt: 
    
C.8.1 Title 
    
   - Changed to "LDAP: The Protocol" to be consisted with other working 
     group documents 
    
C.8.2 Abstract 
    
   - Moved above TOC to conform to new guidelines 
    
   - Reworded to make consistent with other WG documents. 
    
   - Moved 2119 conventions to "Conventions" section 
    
C.8.3 Introduction 
    
   - Created to conform to new guidelines 
    
C.8.4 Models 
    
   - Removed section. There is only one model in this document 
     (Protocol Model)  
    
C.8.5 Protocol Model 
    
   - Removed antiquated paragraph: "In keeping with the goal of easing 
     the costs associated with use of the directory, it is an objective 
     of this protocol to minimize the complexity of clients so as to 
     facilitate widespread deployment of applications capable of using 
     the directory." 
    
   - Removed antiquated paragraph concerning LDAP v1 and v2 and 
     referrals. 
    
C.8.6 Data Model 
    
   - Removed Section 3.2 and subsections. These have been moved to 
     [Models] 
    
C.8.7 Relationship to X.500 
    
   - Removed section. It has been moved to [Roadmap] 
    
C.8.8 Server Specific Data Requirements 
    
   - Removed section. It has been moved to [Models] 
    
C.8.9 Elements of Protocol 
    

  
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   - Added "Section 5.1 specifies how the protocol is encoded and 
     transferred." to the end of the first paragraph for reference. 
    
   - Reworded notes about extensibility, and now talk about implied 
     extensibility and the use of ellipses in the ASN.1 
    
   - Removed references to LDAPv2 in third and fourth paragraphs. 
    
C.8.10 Message ID 
    
   - Reworded second paragraph to "The message ID of a request MUST 
     have a non-zero value different from the values of any other 
     requests outstanding in the LDAP session of which this message is 
     a part. The zero value is reserved for the unsolicited 
     notification message." (Added notes about non-zero and the zero 
     value). 
    
C.8.11 String Types 
    
   - Removed ABNF for LDAPOID and added "Although an LDAPOID is encoded 
     as an OCTET STRING, values are limited to the definition of 
     numericoid given in Section 1.3 of [Models]." 
    
C.8.12 Distinguished Name and Relative Distinguished Name 
    
   - Removed ABNF and referred to [Models] and [LDAPDN] where this is 
     defined. 
    
C.8.13 Attribute Type 
    
   - Removed sections. It's now in the [Models] doc. 
    
C.8.14 Attribute Description 
    
   - Removed ABNF and aligned section with [Models] 
    
   - Moved AttributeDescriptionList here. 
    
C.8.15 Transfer Options 
    
   - Added section and consumed much of old options language (while 
     aligning with [Models] 
    
C.8.16 Binary Transfer Option 
    
   - Clarified intent regarding exactly what is to be BER encoded. 
    
   - Clarified that clients must not expect ;binary when not asking for 
     it (;binary, as opposed to ber encoded data). 
    
    
C.8.17 Attribute 
    
   - Use the term "attribute description" in lieu of "type" 
  
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   - Clarified the fact that clients cannot rely on any apparent 
     ordering of attribute values. 
    
C.8.18 LDAPResult 
    
   - To resultCode, added ellipses "..." to the enumeration to indicate 
     extensibility. and added a note, pointing to [LDAPIANA] 
    
   - Removed error groupings ad refer to Appendix A. 
    
C.8.19 Bind Operation 
    
   - Added "Prior to the BindRequest, the implied identity is 
     anonymous. Refer to [AuthMeth] for the authentication-related 
     semantics of this operation." to the first paragraph. 
    
   - Added ellipses "..." to AuthenticationChoice and added a note 
     "This type is extensible as defined in Section 3.6 of [LDAPIANA]. 
     Servers that do not support a choice supplied by a client will 
     return authMethodNotSupported in the result code of the 
     BindResponse." 
    
   - Simplified text regarding how the server handles unknown versions. 
     Removed references to LDAPv2 
    
C.8.20 Sequencing of the Bind Request 
    
   - Aligned with [AuthMeth] In particular, paragraphs 4 and 6 were 
     removed, while a portion of 4 was retained (see C.8.9) 
    
C.8.21 Authentication and other Security Service 
    
   - Section was removed. Now in [AuthMeth] 
    
C.8.22 Continuation References in the Search Result 
    
   - Added "If the originating search scope was singleLevel, the scope 
     part of the URL will be baseObject." 
    
C.8.23 Security Considerations 
    
   - Removed reference to LDAPv2 
    
C.8.24 Result Codes 
    
   - Added as normative appendix A 
    
C.8.25 ASN.1 
    
   - Added EXTENSIBILITY IMPLIED 
    
   - Added a number of comments holding referenced to [Models] and 
     [ISO10646]. 
  
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   - Removed AttributeType. It is not used. 
    
    
C.9 Changes made to draft-ietf-ldapbis-protocol-07.txt: 
    
   - Removed all mention of transfer encodings and the binary attribute 
     option 
    
   - Further alignment with [Models]. 
    
   - Added extensibility ellipsis to protocol op choice 
      
   - In 4.1.1, clarified when connections may be dropped due to 
     malformed PDUs 
    
   - Specified which matching rules and syntaxes are used for various 
     filter items 
 
C.10 Changes made to draft-ietf-ldapbis-protocol-08.txt: 
 
C.10.1 Section 4.1.1.1: 
    
   - Clarified when it is and isn't appropriate to return an already 
     used message id. 
 
C.10.2 Section 4.1.11: 
    
   - Clarified that a control only applies to the message it's attached 
     to. 
    
   - Explained that the criticality field is only applicable to certain 
     request messages. 
    
   - Added language regarding the combination of controls. 
 
C.10.3 Section 4.11: 
    
   - Explained that Abandon and Unbind cannot be abandoned, and 
     illustrated how to determine whether an operation has been 
     abandoned. 
 
 
C.11 Changes made to draft-ietf-ldapbis-protocol-09.txt: 
    
   - Fixed formatting 
    
 
C.12 Changes made to draft-ietf-ldapbis-protocol-10.txt: 
    
C.12.1 Section 4.1.4: 
    
   - Removed second paragraph as this language exists in MODELS 
 
  
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C.12.2 Section 4.2.1: 
    
   - Replaced fourth paragraph. It was accidentally removed in an 
     earlier edit. 
 
C.12.2 Section 4.13: 
    
   - Added section describing the StartTLS operation (moved from 
     authmeth) 
 
C.13 Changes made to draft-ietf-ldapbis-protocol-11.txt: 
    
C.13.1 Section 4.1.9 
 
   - Changed "errorMessage" to "diagnosticMessage". Simply to indicate 
     that the field may be non-empty even if a non-error resultCode is 
     present. 
 
C.13.2 Section 4.2: 
    
   - Reconciled language in "name" definition with [AuthMeth] 
    
C.13.3 Section 4.2.1 
    
   - Renamed to "Processing of the Bind Request", and moved some text 
     from 4.2 into this section. 
    
   - Rearranged paragraphs to flow better. 
    
   - Specified that (as well as failed) an abandoned bind operation 
     will leave the connection in an anonymous state. 
    
C.13.4 Section 4.5.3 
    
   - Generalized the second paragraph which cited indexing and 
     searchreferralreferences. 
 
C.14 Changes made to draft-ietf-ldapbis-protocol-12.txt: 
    
   - Reworked bind errors. 
   - General clarifications and edits 
    
Appendix D - Outstanding Work Items 
 
D.0 General 
   - Integrate notational consistency agreements WG will discuss 
     notation consistency. Once agreement happens, reconcile draft. 
    
   - Reconcile problems with [Models]. Section 3.2 was wholly removed. 
     There were some protocol semantics in that section that need to be 
     brought back. Specifically, there was the notion of the server 
     implicitly adding objectclass superclasses when a value is added. 
    
D.1 Make result code usage consistent. 
  
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   - While there is a result code appendix, ensure it speaks of result 
     codes in a general sense, and only highlight specific result codes 
     in  the context of an operation when that operation ties more 
     specific meanings to that result code. 
    
    
D.2 Verify references. 
    
   - Many referenced documents have changed. Ensure references and 
     section numbers are correct. 
    
D.3 Usage of Naming Context 
 
   - Make sure occurrences of "namingcontext" and "naming context" are 
     consistent with [Models]. Use in section 6.2 should be reworked.   
     It's layers of indirection that matter, not number of contexts.  
     (That is, referrals can be returned for a number of reasons (cross 
     reference, superior, subordinate, busy, not master, etc.) 
    
     Other uses are fine. 
 
D.4 Review 2119 usage 
    
    
D.5 Reconcile with I-D Nits 
    
 
D.23 Section 4.5.3 
    
   - A server MUST NOT return any SearchResultReference if it has not 
     located the baseObject and thus has not searched any entries; in 
     this case it would return a SearchResultDone containing a referral 
     resultCode. 
    
   - Add "Similarly, a server MUST NOT return a SearchResultReference 
     when the scope of the search is baseObject. If a client receives 
     such a SearchResultReference it MUST interpret is as a protocol 
     error and MUST NOT follow it." to the first paragraph. 
     The technical specification doesn't have to describe how a 
     protocol peer should react when its partner violates an absolute. 
 
     OR return noSuchObject. 
    
   - Add "If the scope part of the LDAP URL is present, the client MUST 
     use the new scope in its next request to progress the search. If 
     the scope part is absent the client MUST use subtree scope to 
     complete subtree searches and base scope to complete one level 
     searches." to the third paragraph. 
    
D.25 Section 4.6 
    

  
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   - Resolve the meaning of "and is ignored if the attribute does not 
     exist". See "modify: "non-existent attribute"" on the list. Not 
     sure if there's really an issue here. Will look at archive 
    
D.27 Section 4.10 
    
   - Specify what happens when the attr is missing vs. attr isn't in 
     schema. Also what happens if there's no equality matching rule. 
     noSuchAttribute, undefinedAttributeType, inappropriateMatching 
    
D.30 Section 5.1 
    
   - Add "control and extended operation values" to last paragraph. See 
     "LBER (BER Restrictions)" on list. 
    
D.32 Section 6.1 
    
   - Add "that are used by those attributes" to the first paragraph. 
   - Add "Servers which support update operations MUST, and other 
     servers SHOULD, support strong authentication mechanisms described 
     in [RFC2829]." as a second paragraph. Likely should just say 
     Requirements of authentication methods, SASL mechanisms, and TLS 
     are described in [AUTHMETH]." (also apply to next two below) 
   - Add "Servers which provide access to sensitive information MUST, 
     and other servers SHOULD support privacy protections such as those 
     described in [RFC2829] and [RFC2830]." as a third paragraph. 
    
D.33 Section 7 
    
   - Add "Servers which support update operations MUST, and other 
     servers SHOULD, support strong authentication mechanisms described 
     in [RFC2829]." as a fourth paragraph. 
   - Add "In order to automatically follow referrals, clients may need 
     to hold authentication secrets. This poses significant privacy and 
     security concerns and SHOULD be avoided." as a sixth paragraph. 
     There are concerns with "automatic" chasing regardless of which, 
     if any, authentication method/mechanism is used. 
    
   - Add notes regarding DoS attack found by CERT advisories. 
    
D.34 Appendix C 
 
   - C.9. Explain why we removed ;binary, and what clients can do to 
     get around potential problems (likely refer to an I-D) 
    
    








  
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