private function checkIdentity(){
        if(isset($_SESSION['REMOTE_ADDR']) && isset($_SESSION['HTTP_USER_AGENT'])){            
            if($_SESSION['REMOTE_ADDR'] != $this->serverVars['REMOTE_ADDR'] || $_SESSION['HTTP_USER_AGENT'] != $this->serverVars['HTTP_USER_AGENT']) {
                Error::general_error('Session - Identity', 'There are a problem with the Sesion identity');
                exit;
            }
        }
        else{
            $_SESSION['REMOTE_ADDR'] = $this->serverVars['REMOTE_ADDR'];
            $_SESSION['HTTP_USER_AGENT'] = $this->serverVars['HTTP_USER_AGENT'];            
        }
    }