add ftp and smb to readme, list dependencies

README.md

@@ -1,12 +1,65 @@
 External user authentication
 ============================
-
 Authenticate user login against FTP, IMAP or SMB.
 
+Passwords are not stored locally; authentication always happens against
+the remote server.
 
-## Configuration
+It stores users and their display name in its own database table
+`users_external`.
+When modifying the `user_backends` configuration, you need to
+update the database table's `backend` field, or your users will lose
+their configured display name.
 
-### IMAP
+If something does not work, check the log file at `owncloud/data/owncloud.log`.
+
+
+FTP
+---
+Authenticate owncloud users against a FTP server.
+
+
+### Configuration
+You only need to supply the FTP host name or IP.
+
+The second - optional - parameter determines if SSL should be used or not.
+
+Add the following to `config.php`:
+
+    'user_backends' => array(
+        array(
+            'class' => 'OC_User_FTP',
+            'arguments' => array('127.0.0.1'),
+        ),
+    ),
+
+To enable SSL connections via `ftps`, append a second parameter `true`:
+
+    'user_backends' => array(
+        array(
+            'class' => 'OC_User_FTP',
+            'arguments' => array('127.0.0.1', true),
+        ),
+    ),
+
+
+### Dependencies
+PHP automatically contains basic FTP support.
+
+For SSL-secured FTP connections via ftps, the PHP [openssl extension][0]
+needs to be activated.
+
+[0]: http://php.net/openssl
+
+
+
+IMAP
+----
+Authenticate owncloud users against an IMAP server.
+IMAP user and password need to be given for the owncloud login
+
+
+### Configuration
 Add the following to your `config.php`:
 
     'user_backends' => array(
@@ -18,9 +71,39 @@ Add the following to your `config.php`:
         ),
     ),
 
-This connects to the IMAP server on `localhost`.
+This connects to the IMAP server on IP `127.0.0.1`, in readonly mode.
 
 Read the [imap_open][0] PHP manual page to learn more about the allowed
 parameters.
 
 [0]: http://php.net/imap_open#refsect1-function.imap-open-parameters
+
+
+### Dependencies
+The PHP [IMAP extension][1] has to be activated.
+
+[1]: http://php.net/imap
+
+
+
+Samba
+-----
+Utilizes the `smbclient` executable to authenticate against a windows
+network machine via SMB.
+
+
+### Configuration
+The only supported parameter is the hostname of the remote machine.
+
+Add the following to your `config.php`:
+
+    'user_backends' => array(
+        array(
+            'class' => 'OC_User_SMB',
+            'arguments' => array('127.0.0.1'),
+        ),
+    ),
+
+
+### Dependencies
+The `smbclient` executable needs to be installed and accessible within `$PATH`.