Updated the LDAP auth module README.

modules/auth/ldap/README.md

@@ -4,17 +4,30 @@ Gogs LDAP Authentication Module
 ## About
 
 This authentication module attempts to authorize and authenticate a user
-against an LDAP server. Like most LDAP authentication systems, this module does
-this in two steps. First, it queries the LDAP server using a Bind DN and
+against an LDAP server. It provides two methods of authenitcation: LDAP via
+BindDN, and LDAP simple authentication.
+
+LDAP via BindDN functions like most LDAP authentication systems.
+First, it queries the LDAP server using a Bind DN and
 searches for the user that is attempting to sign in. If the user is found, the
 module attempts to bind to the server using the user's supplied credentials. If
 this succeeds, the user has been authenticated, and his account information is
 retrieved and passed to the Gogs login infrastructure.
 
+LDAP simple authentication does not utilize a Bind DN. Instead, it binds
+directly with the LDAP server using the user's supplied credentials. If the bind
+succeeds and no filter rules out the user, the user is authenticated.
+
+LDAP via BindDN is recommended for most users. By using a Bind DN, the server
+can perform authorization by restricting which entries the Bind DN account can
+read. Further, using a Bind DN with reduced permissions can reduce security risk
+in the face of application bugs.
+
 ## Usage
 
 To use this module, add an LDAP authentication source via the Authentications
-section in the admin panel. The fields should be set as follows:
+section in the admin panel. Both the LDAP via BindDN and the simple auth LDAP
+share the following fields:
 
 * Authorization Name **(required)**
     * A name to assign to the new method of authorization.
@@ -30,35 +43,58 @@ section in the admin panel. The fields should be set as follows:
 * Enable TLS Encryption (optional)
     * Whether to use TLS when connecting to the LDAP server.
 
+* Admin Filter (optional)
+    * An LDAP filter specifying if a user should be given administrator
+      privileges. If a user accounts passes the filter, the user will be
+      privileged as an administrator.
+    * Example: (objectClass=adminAccount)
+
+* First name attribute (optional)
+    * The attribute of the user's LDAP record containing the user's first name.
+      This will be used to populate their account information.
+    * Example: givenName
+
+* Surname attribute (optional)
+    * The attribute of the user's LDAP record containing the user's surname This
+      will be used to populate their account information.
+    * Example: sn
+
+* E-mail attribute **(required)**
+    * The attribute of the user's LDAP record containing the user's email
+      address. This will be used to populate their account information.
+    * Example: mail
+
+**LDAP via BindDN** adds the following fields:
+
 * Bind DN (optional)
-	* The DN to bind to the LDAP server with when searching for the user.
-	This may be left blank to perform an anonymous search.
+    * The DN to bind to the LDAP server with when searching for the user. This
+      may be left blank to perform an anonymous search.
     * Example: cn=Search,dc=mydomain,dc=com
 
 * Bind Password (optional)
-	* The password for the Bind DN specified above, if any.
+    * The password for the Bind DN specified above, if any. _Note: The password
+      is stored in plaintext at the server. As such, ensure that your Bind DN
+      has as few privileges as possible._
 
 * User Search Base **(required)**
     * The LDAP base at which user accounts will be searched for.
     * Example: ou=Users,dc=mydomain,dc=com
 
 * User Filter **(required)**
-	* An LDAP filter declaring how to find the user record that is attempting
-	to authenticate. The '%s' matching parameter will be substituted with
-	the user's username.
+    * An LDAP filter declaring how to find the user record that is attempting to
+      authenticate. The '%s' matching parameter will be substituted with the
+      user's username.
     * Example: (&(objectClass=posixAccount)(uid=%s))
 
-* First name attribute (optional)
-	* The attribute of the user's LDAP record containing the user's first
-	name. This will be used to populate their account information.
-	* Example: givenName
+**LDAP using simple auth** adds the following fields:
 
-* Surname name attribute (optional)
-	* The attribute of the user's LDAP record containing the user's surname
-	This will be used to populate their account information.
-	* Example: sn
+* User DN **(required)**
+    * A template to use as the user's DN. The `%s` matching parameter will be
+      substituted with the user's username.
+    * Example: cn=%s,ou=Users,dc=mydomain,dc=com
+    * Example: uid=%s,ou=Users,dc=mydomain,dc=com
 
-* E-mail attribute **(required)**
-	* The attribute of the user's LDAP record containing the user's email
-	address. This will be used to populate their account information.
-	* Example: mail
+* User Filter **(required)**
+    * An LDAP filter declaring when a user should be allowed to log in. The `%s`
+      matching parameter will be substituted with the user's username.
+    * Example: (&(objectClass=posixAccount)(uid=%s))