The Directory Server provides a set of operational attributes that restricts the proxied authorization capabilities of a client application and its proxyable target entry. When present in an entry, the Directory Server evaluates each operational attribute together to form a whitelist of potential users that can be proxied. If none of those attributes is present, then the user may potentially proxy as anyone.

The Directory Server supports a two-tier provision system that, when configured, can restrict specific users for proxied authorization. The first tier is a set of ds-auth-may-proxy-as-* operational attributes on the client entry that will bind to the server and carry out operations under the identity of another user. The second tier is a set of ds-auth-is-proxyable-* operational attributes on the user entry that defines whether access is allowed, prohibited, or required by means of proxied authorization. If allowed or required, the attributes define which client entries can proxy as the user.

Proxying Operational Attributes Example
For example, if a client application, such as uid=clientApp, is requesting to search the ou=People,dc=example,dc=com branch as the user uid=admin, the command would look like this:
ldapsearch --bindDN uid=clientApp,dc=example,dc=com \
--bindPassword password \
--proxyAs uid=admin,dc=example,dc=com \
--baseDN ou=People,dc=example,dc=com \

At bind, the Directory Server evaluates the list of users in the uid=clientApp entry based on the presence of any ds-auth-may-proxy-as-* attributes. In the figure below, the uid=clientApp entry has a ds-auth-may-proxy-as attribute with a value, uid=admin, which means that the client app user may proxy only as the uid=admin account. Next, the server confirms that uid=admin is in the list of proxyable users and then evaluates the ds-auth-is-proxyable-* attributes present in the uid=admin entry. These attributes determine the list of restricted users that either are allowed, prohibited, or required to proxy as the uid=admin entry. In this case, the uid=admin entry has the ds-auth-is-proxyable attribute with a value of "required", which indicates that the entry can only be accessed by means of proxied authorization. The uid=admin entry also has the ds-auth-is-proxyable-by attribute with a value of uid=clientApp, which indicates it can only be requested by the uid=clientApp entry. Once both sets of attributes have been confirmed, the uid=clientApp can bind to the server as the authenticated user. From this point, the Directory Server performs ACI evaluation on the branch to determine if the requested user has access rights to the branch. If the branch is accessible by the uid=clientApp entry, and then the search request is processed.