4. Authorization State

Every LDAP session has an associated authorization state. This state is comprised of numerous factors such as what (if any) authentication state has been established, how it was established, and what security services are in place. Some factors may be determined and/or affected by protocol events (e.g., Bind, StartTLS, or TLS closure), and some factors may be determined by external events (e.g., time of day or server load).

While it is often convenient to view authorization state in simplistic terms (as we often do in this technical specification) such as "an anonymous state", it is noted that authorization systems in LDAP implementations commonly involve many factors that interrelate in complex manners.

Authorization in LDAP is a local matter. One of the key factors in making authorization decisions is authorization identity. The Bind operation (defined in Section 4.2 of [RFC4511] and discussed further in Section 5 below) allows information to be exchanged between the client and server to establish an authorization identity for the LDAP session. The Bind operation may also be used to move the LDAP session to an anonymous authorization state (see Section 5.1.1).

Upon initial establishment of the LDAP session, the session has an anonymous authorization identity. Among other things this implies that the client need not send a BindRequest in the first PDU of the LDAP message layer. The client may send any operation request prior to performing a Bind operation, and the server MUST treat it as if it had been performed after an anonymous Bind operation (Section 5.1.1).

Upon receipt of a Bind request, the server immediately moves the session to an anonymous authorization state. If the Bind request is successful, the session is moved to the requested authentication state with its associated authorization state. Otherwise, the session remains in an anonymous state.

It is noted that other events both internal and external to LDAP may result in the authentication and authorization states being moved to an anonymous one. For instance, the establishment, change, or closure of data security services may result in a move to an anonymous state, or the user's credential information (e.g., certificate) may have expired. The former is an example of an event internal to LDAP, whereas the latter is an example of an event external to LDAP.