= Locating the user

No matter how the LDAP module is called (via its `authorize`, `authenticate`,
`accounting` methods or the `%ldap.memberof()` xlat) the first operation the
module performs it to populate `&control.LDAP-UserDN` with the location of
the authenticating user's object in LDAP.

Below is an example of configuring a user section for OpenLDAP, with callouts
explaining how the different configuration items are used. See
xref:modules/ldap/ldapsearch/index.adoc[ldapsearch] for how to determine the
appropriate values for your directory.

== Editing mods-available/ldap to specify how to search for user objects

[source,config]
----
ldap {
	user {
		# example - ou=people,${..base_dn}
		base_dn = "<user.base_dn>" <1>

		# example - (&(objectClass=posixAccount)(uid=%{&Stripped-User-Name || &User-Name}))
		filter = "(&(<user.filter>)(<user_uid_attribute>=%{&Stripped-User-Name || &User-Name}))"  <2>
	}
}
----

<1> Where in the directory to begin the search for the user object.
    This must be a point in the directory tree containing the objects for
    all users that might authenticate.
<2> The filter used to locate the user object belonging to the
    authenticating user.  The user filter is normally a combination of two
    subfilters.
    The first subfilter specifies the objectClass of user objects.
    The second filter selects a user object matching the username the
    user provided at login.

[WARNING]
====
It is important that the `user.base_dn` and `user.filter` values are restrictive
enough to return only a single entry when searching for users. If multiple entries
are returned the LDAP module will fail.

See xref:modules/ldap/authorization/user_disambiguation.adoc[User object
disambiguation] for strategies for limiting the number of user object entries
returned.
====
