In computing, an Object Identifier or OID or LDAPOID is an identifier used to name an object (compare URN). Structurally, an OID consists of a node in a hierarchically-assigned namespace, formally defined using the ITU-T's ASN.1 standard. Successive numbers of the nodes, starting at the root of the tree, identify each node in the tree. Designers set up new nodes by registering them under the node's registration authority. The root of the tree contains the following three arcs:


LDAP Object Identifier#

LDAP Object Identifier are specifically defined at: LDAP Object Identifier Descriptors

X.500 Object IDentifiers (OIDs)#

The LDAP "Data model", mentions every objectClass must be uniquely identified by an OID. But what is an OID?

Every objectClass that is part of a LDAP Schema receives a dotted decimal hierarchical identifier. These OIDs can be organized in a tree structure, very similar to the X.500 DIT , called Object Identifier Tree (OIT). They were defined by the X.208 standard, and they have been revised and updated by the X.680 standard. Immediately below the root of this tree, there are only three values currently defined as shown above.

Each LDAP Schema element is identified by a globally unique Object Identifier (OID). OIDs are also used to identify other objects. They are commonly found in protocols described by ASN.1. In particular, they are heavily used by the Simple Network Management Protocol (SNMP). As OIDs are hierarchical, your organization can obtain one OID and branch it as needed.

You can design a hierarchy suitable to your organizational needs under your organization's OID. No matter what hierarchy you choose, you should maintain a registry of assignments you make. This can be a simple flat file or a something more sophisticated such as the OpenLDAP OID Registry. For more information about Object Identifiers (and a listing service) see http://www.alvestrand.no/harald/objectid/.

Under no circumstances should you use a fictitious OID!#

To obtain a fully registered OID at no cost, apply for an OID under Internet Assigned Numbers Authority (IANA) maintained Private Enterprise arch. Any private enterprise (organization) may request an OID to be assigned under this arch. Just fill out the IANA form and your official OID will be sent to you usually within a few days. Your base OID will be something like were X is an integer.

Microsoft has an OID for Microsft Base OID for Customer Usage[1] and even a script to help generate them[2]

LDAP Schema Usage#

An object identifier, OID, is a string that is comprised of a series of integers separated by periods. It is used as a unique identifier for various types of elements in the Directory Server, including:

How To Get Your Own OID#

We show you How To Get Your Own OID, free!
Don't let the "MIB/SNMP" statement on the IANA page confuse you. OIDs obtained using this form may be used for any purpose including identifying LDAP Schema elements. Name Prefixes

External Links for More Information#

More Information#

There might be more information for this subject on one of the following: