diff --git a/xCAT-UI/lib/systemcmd.php b/xCAT-UI/lib/systemcmd.php
index 6fc9be412..8925822a2 100644
--- a/xCAT-UI/lib/systemcmd.php
+++ b/xCAT-UI/lib/systemcmd.php
@@ -12,6 +12,10 @@ require_once "$TOPDIR/lib/jsonwrapper.php";
  * @param 	$cmd	The system command
  * @return 	The system response.  Replies are in the form of JSON
  */
+if (!isAuthenticated()){
+	echo ("<b>Please log in from the main page first!</b>");
+	exit;
+}
 
 if (isset($_GET["cmd"])) {
     // HTTP GET requests