diff --git a/auth/cas/config.html b/auth/cas/config.html
index ea603acc046..964946b8ee3 100644
--- a/auth/cas/config.html
+++ b/auth/cas/config.html
@@ -8,6 +8,7 @@
     optional_variable($config->cas_language,"");
     optional_variable($config->cas_use_cas,"");
     optional_variable($config->cas_create_user,"0");
+    optional_variable($config->cas_logout,"");
 ?>
 
 
@@ -95,6 +96,20 @@
     </td>
 </tr>
 
+<tr valign="top"  class="required">
+    <td align="right">cas_logout:</td>
+    <td>
+    <?php
+       unset($options);
+       $options[0] = get_string("no");
+       $options[1] = get_string("yes");
+
+       choose_from_menu ($options, "cas_logout", $config->cas_logout, "");?>
+    </td><td>
+    <?php  print_string("auth_cas_logout","auth") ?>
+    </td>
+</tr>
+
 <?php
     include($CFG->dirroot.'/auth/ldap/config.html');
 ?>
diff --git a/auth/cas/lib.php b/auth/cas/lib.php
index ff348ae0b68..fa7052e421f 100644
--- a/auth/cas/lib.php
+++ b/auth/cas/lib.php
@@ -99,12 +99,9 @@ function cas_authenticate_user_login ($username, $password) {
 
    global $CFG;
    $cas_validate=true;
-
    phpCAS::client($CFG->cas_version,$CFG->cas_hostname,(Integer)$CFG->cas_port,$CFG->cas_baseuri);
    phpCAS::setLang($CFG->cas_language);
-   if (!phpCAS::isAuthenticated()){
-      phpCAS::authenticateIfNeeded();
-   }
+   phpCAS::forceAuthentication();
    if ($CFG->cas_create_user=="0"){
       if (record_exists('user', 'username', phpCAS::getUser())) {
          $user = authenticate_user_login(phpCAS::getUser(), 'cas');
@@ -138,10 +135,11 @@ function cas_automatic_authenticate ($user="") {
         $cas_validate=true;
         phpCAS::client($CFG->cas_version,$CFG->cas_hostname,(Integer)$CFG->cas_port,$CFG->cas_baseuri);
         phpCAS::setLang($CFG->cas_language);
-        if (!phpCAS::isAuthenticated() && !$CFG->guestloginbutton){
-           phpCAS::authenticateIfNeeded();
+        $cas_user_exist=phpCAS::checkAuthentication();
+        if (!$cas_user_exist && !$CFG->guestloginbutton){
+           $cas_user_exist=phpCAS::forceAuthentication();
         }
-        if (phpCAS::isAuthenticated()){
+        if ($cas_user_exist){
            if ($CFG->cas_create_user=="0"){
               if (record_exists('user', 'username', phpCAS::getUser())) {
                  $user = authenticate_user_login(phpCAS::getUser(), 'cas');
@@ -167,4 +165,5 @@ function cas_automatic_authenticate ($user="") {
    }
 }
 
-?>
+
+?>
\ No newline at end of file
diff --git a/auth/cas/logout.php b/auth/cas/logout.php
index 210c19a35c5..6fba17ef0a8 100644
--- a/auth/cas/logout.php
+++ b/auth/cas/logout.php
@@ -1,11 +1,15 @@
-<?php 
+<?php
 // $Id$
 // logout the user from CAS server (destroy the ticket)
 defined('MOODLE_INTERNAL') or die('Direct access to this script is forbidden.');
 
-       include_once($CFG->dirroot.'/lib/cas/CAS.php');
-       phpCAS::client($CFG->cas_version,$CFG->cas_hostname,(Integer)$CFG->cas_port,$CFG->cas_baseuri);
-       $backurl = $CFG->wwwroot;
-       phpCAS::logout($backurl);
+       global $CFG;
+       if ($CFG->cas_logout){
+         require_once($CFG->dirroot.'/config.php');
+         include_once($CFG->dirroot.'/lib/cas/CAS.php');
+         phpCAS::client($CFG->cas_version,$CFG->cas_hostname,(Integer)$CFG->cas_port,$CFG->cas_baseuri);
+         $backurl = $CFG->wwwroot;
+         phpCAS::logout($backurl);
+       }
 
 ?>
\ No newline at end of file