diff --git a/appinfo/app.php b/appinfo/app.php
index b7ae102..de6bb40 100644
--- a/appinfo/app.php
+++ b/appinfo/app.php
@@ -1,4 +1,5 @@
 <?php
+OC::$CLASSPATH['OC_User_External_Base']='user_external/lib/base.php';
 OC::$CLASSPATH['OC_User_IMAP']='user_external/lib/imap.php';
 OC::$CLASSPATH['OC_User_SMB']='user_external/lib/smb.php';
 OC::$CLASSPATH['OC_User_FTP']='user_external/lib/ftp.php';
diff --git a/appinfo/database.xml b/appinfo/database.xml
new file mode 100644
index 0000000..0c97b82
--- /dev/null
+++ b/appinfo/database.xml
@@ -0,0 +1,57 @@
+<?xml version="1.0" encoding="ISO-8859-1" ?>
+<database>
+
+ <name>*dbname*</name>
+ <create>true</create>
+ <overwrite>false</overwrite>
+
+ <charset>utf8</charset>
+
+ <table>
+
+  <name>*dbprefix*users_external</name>
+
+  <declaration>
+
+   <field>
+    <name>backend</name>
+    <type>text</type>
+    <default></default>
+    <notnull>true</notnull>
+    <length>255</length>
+   </field>
+
+   <field>
+    <name>uid</name>
+    <type>text</type>
+    <default></default>
+    <notnull>true</notnull>
+    <length>64</length>
+   </field>
+
+   <field>
+    <name>displayname</name>
+    <type>text</type>
+    <default></default>
+    <length>64</length>
+   </field>
+
+   <index>
+    <name>users_unique</name>
+    <primary>true</primary>
+    <unique>true</unique>
+    <field>
+     <name>uid</name>
+     <sorting>ascending</sorting>
+    </field>
+    <field>
+     <name>backend</name>
+     <sorting>ascending</sorting>
+    </field>
+   </index>
+
+  </declaration>
+
+ </table>
+
+</database>
diff --git a/appinfo/version b/appinfo/version
index ceab6e1..1d71ef9 100644
--- a/appinfo/version
+++ b/appinfo/version
@@ -1 +1 @@
-0.1
\ No newline at end of file
+0.3
\ No newline at end of file
diff --git a/lib/base.php b/lib/base.php
new file mode 100644
index 0000000..a8eb15b
--- /dev/null
+++ b/lib/base.php
@@ -0,0 +1,140 @@
+<?php
+/**
+ * Copyright (c) 2013 Christian Weiske <cweiske@cweiske.de>
+ * This file is licensed under the Affero General Public License version 3 or
+ * later.
+ * See the COPYING-README file.
+ */
+
+/**
+ * Base class for external auth implementations that stores users
+ * on their first login in a local table.
+ * This is required for making many of the user-related owncloud functions
+ * work, including sharing files with them.
+ */
+abstract class OC_User_External_Base extends OC_User_Backend{
+	protected $backend = '';
+
+	public function __construct($backend) {
+		$this->backend = $backend;
+	}
+
+	/**
+	 * @brief delete a user
+	 * @param string $uid The username of the user to delete
+	 * @return bool
+	 *
+	 * Deletes a user
+	 */
+	public function deleteUser($uid) {
+		$query = OC_DB::prepare('DELETE FROM `*PREFIX*users_external` WHERE `uid` = ? AND backend = ?');
+		$query->execute(array($uid, $this->backend));
+		return true;
+	}
+
+	/**
+	 * @brief get display name of the user
+	 * @param $uid user ID of the user
+	 * @return string display name
+	 */
+	public function getDisplayName($uid) {
+		$query = OC_DB::prepare('SELECT `displayname` FROM `*PREFIX*users_external` WHERE `uid` = ? AND backend = ?');
+		$result = $query->execute(array($uid, $this->backend))->fetchAll();
+		$displayName = trim($result[0]['displayname'], ' ');
+		if (!empty($displayName)) {
+			return $displayName;
+		} else {
+			return $uid;
+		}
+	}
+
+	/**
+	 * @brief Get a list of all display names
+	 * @returns array with  all displayNames (value) and the correspondig uids (key)
+	 *
+	 * Get a list of all display names and user ids.
+	 */
+	public function getDisplayNames($search = '', $limit = null, $offset = null) {
+		$displayNames = array();
+		$query = OC_DB::prepare('SELECT `uid`, `displayname` FROM `*PREFIX*users_external`'
+			. ' WHERE (LOWER(`displayname`) LIKE LOWER(?) OR '
+			. 'LOWER(`uid`) LIKE LOWER(?)) AND backend = ?', $limit, $offset);
+		$result = $query->execute(array($search . '%', $search . '%', $this->backend));
+		$users = array();
+		while ($row = $result->fetchRow()) {
+			$displayNames[$row['uid']] = $row['displayname'];
+		}
+
+		return $displayNames;
+	}
+
+	/**
+	* @brief Get a list of all users
+	* @returns array with all uids
+	*
+	* Get a list of all users.
+	*/
+	public function getUsers($search = '', $limit = null, $offset = null) {
+		$query = OC_DB::prepare('SELECT `uid` FROM `*PREFIX*users_external` WHERE LOWER(`uid`) LIKE LOWER(?) AND backend = ?', $limit, $offset);
+		$result = $query->execute(array($search . '%', $this->backend));
+		$users = array();
+		while ($row = $result->fetchRow()) {
+			$users[] = $row['uid'];
+		}
+		return $users;
+	}
+
+	/**
+	 * @return bool
+	 */
+	public function hasUserListings() {
+		return true;
+	}
+
+	/**
+	 * @brief Set display name
+	 * @param $uid The username
+	 * @param $displayName The new display name
+	 * @returns true/false
+	 *
+	 * Change the display name of a user
+	 */
+	public function setDisplayName($uid, $displayName) {
+		if ($this->userExists($uid)) {
+			$query = OC_DB::prepare('UPDATE `*PREFIX*users_external` SET `displayname` = ? WHERE LOWER(`uid`) = ? AND backend = ?');
+			$query->execute(array($displayName, $uid, $this->backend));
+			return true;
+		} else {
+			return false;
+		}
+	}
+
+	/**
+	 * @brief Create user record in database
+	 * @param $uid The username
+	 * @returns void
+	 */
+	protected function storeUser($uid)
+	{
+		if (!$this->userExists($uid)) {
+			$query = OC_DB::prepare('INSERT INTO `*PREFIX*users_external` ( `uid`, `backend` ) VALUES( ?, ? )');
+			$result = $query->execute(array($uid, $this->backend));
+		}
+	}
+
+	/**
+	 * @brief check if a user exists
+	 * @param string $uid the username
+	 * @return boolean
+	 */
+	public function userExists($uid) {
+		$query = OC_DB::prepare('SELECT COUNT(*) FROM `*PREFIX*users_external` WHERE LOWER(`uid`) = LOWER(?) AND backend = ?');
+		$result = $query->execute(array($uid, $this->backend));
+		if (OC_DB::isError($result)) {
+			OC_Log::write('user_external', OC_DB::getErrorMessage($result), OC_Log::ERROR);
+			return false;
+		}
+		return $result->fetchOne() > 0;
+	}
+}
+?>
diff --git a/lib/ftp.php b/lib/ftp.php
index b94d7fe..35d9aa4 100644
--- a/lib/ftp.php
+++ b/lib/ftp.php
@@ -6,7 +6,7 @@
  * See the COPYING-README file.
  */
 
-class OC_User_FTP extends OC_User_Backend{
+class OC_User_FTP extends OC_User_External_Base{
 	private $host;
 	private $secure;
 	private $protocol;
@@ -18,6 +18,7 @@ class OC_User_FTP extends OC_User_Backend{
 		if($this->secure) {
 			$this->protocol.='s';
 		}
+		parent::__construct($this->protocol . '://' . $this->host);
 	}
 
 	/**
@@ -36,13 +37,10 @@ class OC_User_FTP extends OC_User_Backend{
 		$url = sprintf('%s://%s:%s@%s/', $this->protocol, $uid, $password, $this->host);
 		$result=@opendir($url);
 		if(is_resource($result)) {
+			$this->storeUser($uid);
 			return $uid;
 		}else{
 			return false;
 		}
 	}
-
-	public function userExists($uid) {
-		return true;
-	}
 }
diff --git a/lib/imap.php b/lib/imap.php
index d1c6263..6a6fe23 100644
--- a/lib/imap.php
+++ b/lib/imap.php
@@ -6,10 +6,11 @@
  * See the COPYING-README file.
  */
 
-class OC_User_IMAP extends OC_User_Backend{
+class OC_User_IMAP extends OC_User_External_Base {
 	private $mailbox;
 
 	public function __construct($mailbox) {
+		parent::__construct($mailbox);
 		$this->mailbox=$mailbox;
 	}
 
@@ -31,13 +32,10 @@ class OC_User_IMAP extends OC_User_Backend{
 		imap_alerts();
 		if($mbox) {
 			imap_close($mbox);
+			$this->storeUser($uid);
 			return $uid;
 		}else{
 			return false;
 		}
 	}
-
-	public function userExists($uid) {
-		return true;
-	}
 }
diff --git a/lib/smb.php b/lib/smb.php
index 8a95120..d2bd5af 100644
--- a/lib/smb.php
+++ b/lib/smb.php
@@ -13,6 +13,7 @@ class OC_User_SMB extends OC_User_Backend{
 	const loginError='NT_STATUS_LOGON_FAILURE';
 
 	public function __construct($host) {
+		parent::__construct($host);
 		$this->host=$host;
 	}
 
@@ -41,11 +42,8 @@ class OC_User_SMB extends OC_User_Backend{
 			OCP\Util::writeLog('user_external', 'ERROR: smbclient error: ' . trim($lastline), OCP\Util::ERROR);
 			return false;
 		} else {
+			$this->storeUser($uid);
 			return $uid;
 		}
 	}
-
-	public function userExists($uid) {
-		return true;
-	}
 }
\ No newline at end of file