Zend auth checking

 public function authAction()  
   {  
     $request   = $this->getRequest();  
     $registry   = Zend_Registry::getInstance();  
     $auth    = Zend_Auth::getInstance();  
     $DB = Zend_Db_Table::getDefaultAdapter();  
     $authAdapter = new Zend_Auth_Adapter_DbTable($DB);  
     $authAdapter->setTableName('user')  
           ->setIdentityColumn('user_name')  
           ->setCredentialColumn('password');    
     // Set the input credential values  
     $uname = $request->getParam('user_name');  
     $paswd = $request->getParam('password');  
     $authAdapter->setIdentity($uname);  
     $authAdapter->setCredential(md5($paswd));  
     // Perform the authentication query, saving the result  
     $result = $auth->authenticate($authAdapter);  
     if($result->isValid())  
     {  
       $data = $authAdapter->getResultRowObject(null,'password');  
       $auth->getStorage()->write($data);  
       $this->_redirect('user/index/listuser');  
     }  
     else  
     {  
       $this->_flashMessenger->addMessage($this->view->translator('user_invalid_login'));  
       $this->_redirect('user/index/login');  
     }  
   }  

zend db connection

 resources.db.adapter = "PDO_MYSQL"  
 resources.db.isDefaultAdapter = true  
 resources.db.params.host = "localhost"  
 resources.db.params.username = ""  
 resources.db.params.password = ""  
 resources.db.params.dbname = "zend_learn"  
 ----------  
 {      
     $form = new User_Form_loginForm();  
     $this->view->form = $form;  
 }  
 -----------  
 class User_Form_loginForm extends Zend_Form  
 {  
   public function init()  
   {  
     $request = Zend_Controller_Front::getInstance()->getRequest();  
     $action = $request->getBaseUrl().'/'.$request->getModuleName().'/'.$request->getControllerName().'/auth';  
     $this->setMethod('post')  
        ->setName('frmlogin')  
        ->setAttrib('id', 'frmlogin')  
        ->setAction($action);  
     $username = $this->createElement('text', 'user_name');  
     $username->setAttrib('class', 'required')  
          ->setAttrib('minlength', 4)  
          ->setAttrib('maxlength', 15)  
          //->addFilter(array('StripTags', 'StringTrim'))  
          ->addFilter('StripTags')  
          ->addFilter('StringTrim')  
          ->setRequired(true);  
     $password = $this->createElement('password', 'password');  
     $password->setAttrib('class', 'required')  
          ->setRequired(true);  
     $submit = $this->createElement('submit', 'login');  
     $this->addElements(array($username, $password, $submit));  
   }  
 }