RFC 5020

The Lightweight Directory Access Protocol (LDAP) entryDN Operational Attribute

📅 published August 2007, from ietf

The Lightweight Directory Access Protocol (LDAP) entryDN Operational Attribute ✨

Okay bestie, this is RFC 5020 🎀 It's from the Network Working Group, written by Kurt D. Zeilenga of Isode Limited, and dated August 2007. It's on the Standards Track, and its header doesn't list any RFCs it obsoletes or updates, so it's standing on its own 💅

Status of This Memo 📌

This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "Internet Official Protocol Standards" (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited.

Copyright Notice ©️

Abstract 🦋

This document describes the Lightweight Directory Access Protocol (LDAP) / X.500 'entryDN' operational attribute. The attribute provides a copy of the entry's distinguished name for use in attribute value assertions.

1. Background and Intended Use 🌸

So in X.500 Directory Services [X.501], like the ones you can reach with the Lightweight Directory Access Protocol (LDAP) [RFC4510], an entry is identified by its distinguished name (DN) [RFC4512]. The problem is that an entry's DN isn't an attribute of the entry, so you can't run attribute value assertions [RFC4511] against it. Rude 🙄

This document describes the 'entryDN' operational attribute, which holds a copy of the entry's distinguished name. This attribute may be used in search filters. For example, searching the subtree <dc=example,dc=com> with this filter:

(entryDN:componentFilterMatch:=or:{
    item:{ component "3", rule rdnMatch, value "ou=A" },
    item:{ component "3", rule rdnMatch, value "ou=B" } })

would return entries in the subtree <ou=A,dc=example,dc=com> and entries in the subtree <ou=B,dc=example,dc=com>, but would not return any other entries in the subtree <dc=example,dc=com>. It's giving precision 🎯

In the paragraph above, DNs are presented using the string representation defined in [RFC4514], and the example search filter is presented using the string representation defined in [RFC4515], with whitespace (line breaks and indentation) added to make it easier to read. The 'componentFilterMatch' and 'rdnMatch' rules are specified in [RFC3687].

Schema definitions are provided using LDAP description formats [RFC4512]. The definitions in this document are line wrapped for readability, so don't panic when you see the breaks 🫶

2. 'entryDN' Operational Attribute 💜

The 'entryDN' operational attribute provides a copy of the entry's current DN.

Here's the LDAP attribute type description, which is suitable for publishing in subschema subentries:

( 1.3.6.1.1.20 NAME 'entryDN'
    DESC 'DN of the entry'
    EQUALITY distinguishedNameMatch
    SYNTAX 1.3.6.1.4.1.1466.115.121.1.12
    SINGLE-VALUE
    NO-USER-MODIFICATION
    USAGE directoryOperation )

Note that the DN of the entry cannot be modified through this attribute. Hard limit, no edits allowed 🔒

3. Security Considerations 🔐

As this attribute only provides an additional mechanism to access an entry's DN, the introduction of this attribute is not believed to introduce new security considerations.

4. IANA Considerations 🧚

4.1. Object Identifier Registration 🍓

IANA has registered (upon Standards Action) an LDAP Object Identifier [RFC4520] for use in this document. The registration request looks like this:

Subject: Request for LDAP OID Registration
Person & email address to contact for further information:
    Kurt Zeilenga <Kurt.Zeilenga@Isode.COM>
Specification: RFC 5020
Author/Change Controller: IESG
Comments:
    Identifies the 'entryDN' attribute type

4.2. 'entryDN' Descriptor Registration 🌈

IANA has registered (upon Standards Action) the LDAP 'entryDN' descriptor [RFC4520]. The registration request looks like this:

Subject: Request for LDAP Descriptor Registration
Descriptor (short name): entryDN
Object Identifier: 1.3.6.1.1.20
Person & email address to contact for further information:
    Kurt Zeilenga <Kurt.Zeilenga@Isode.COM>
Usage: Attribute Type
Specification: RFC 5020
Author/Change Controller: IESG

5. References 📚

5.1. Normative References 👑

[RFC4510]   Zeilenga, K., Ed., "Lightweight Directory Access Protocol
            (LDAP): Technical Specification Road Map", RFC 4510, June
            2006.

[RFC4512]   Zeilenga, K., Ed., "Lightweight Directory Access Protocol
            (LDAP): Directory Information Models", RFC 4512, June
            2006.

[X.501]     International Telecommunication Union - Telecommunication
            Standardization Sector, "The Directory -- Models,"
            X.501(1993) (also ISO/IEC 9594-2:1994).

5.2. Informative References ⭐

[RFC3687]   Legg, S., "Lightweight Directory Access Protocol (LDAP)
            and X.500 Component Matching Rules", RFC 3687, February
            2004.

[RFC4511]   Sermersheim, J., Ed., "Lightweight Directory Access
            Protocol (LDAP): The Protocol", RFC 4511, June 2006.

[RFC4514]   Zeilenga, K., Ed., "Lightweight Directory Access Protocol
            (LDAP): String Representation of Distinguished Names",
            RFC 4514, June 2006.

[RFC4515]   Smith, M., Ed., and T. Howes, "Lightweight Directory
            Access Protocol (LDAP): String Representation of Search
            Filters", RFC 4515, June 2006.

[RFC4520]   Zeilenga, K., "Internet Assigned Numbers Authority (IANA)
            Considerations for the Lightweight Directory Access
            Protocol (LDAP)", BCP 64, RFC 4520, June 2006.

Author's Address 💌

Kurt D. Zeilenga Isode Limited

EMail: Kurt.Zeilenga@Isode.COM

Full Copyright Statement 📝

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Acknowledgement 💖

Funding for the RFC Editor function is currently provided by the Internet Society.

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