用户登录后如何防止浏览器返回登录表单页面？

Question

一旦用户登录，如何防止浏览器返回登录表单页面？？？

    public function fileITR()
{
$this->load->helper('captcha'); 
$this->form_validation->set_rules('pancard','pancard','required');
$this->form_validation->set_rules('password','password','required|min_length[5]');
$this->form_validation->set_rules('captcha','captcha','required');

  if($this->form_validation->run() ==  TRUE )
  {
      $pancard = $_POST['pancard'];
      $password = md5($_POST['password']);

      $this->db->select('*')
               ->from('users')
               ->where(array('pancard' =>$pancard,'pass'=>$password));
      $query = $this->db->get();

      $user = $query->row();

      if($user)
      {
          $this->session->set_flashdata("success","you are logged in");

          $_SESSION['user_logged'] = TRUE;
          $_SESSION['pancard'] = $user->pancard;
          $this->session->userdata('filename');
          redirect("home/UserPage");

      }
      else
      {
      $this->session->set_flashdata("error","No such account exists in database");
      redirect("Home/fileITR" , "refresh");     
      } 
      $this->load->view('fileITR');

  } 

    $file =  $this->session->userdata('filename');
    if($file && file_exists('./captcha/'.$file)) 
    {
       unlink('./captcha/' .$this->session->userdata('filename')); 

    }


    $args = array(
    'img_path' => './captcha/',
    'img_url' => base_url('captcha'), 
    'img_width' => 120,
    'word_length' => 5,
    'font_size' => 10,
    'pool' =>'ABCDEFGHIJKLMNOPQRSTUVWXYZ',
    'colors' => array(
    'background' =>array(255,255,255),
    'border'  =>array(0,0,0),
    'text'   =>array(0,0,0),
    'grid'   =>array(0,0,0)   
    )    
    );

    $cap = create_captcha($args);
    $this->session->set_userdata('captcha_key',$cap['word']);
    $this->session->set_userdata('filename',$cap['filename']);
    $this->load->view('fileITR' , array('captcha' => $cap)); 


}

Answer 1

>请勿将MD5用于密码

>>请勿将MD5用于密码

>>>请勿将MD5用于密码

http://php.net/manual/en/function.password-hash.php

https://security.stackexchange.com/questions/19906/is-md5-considered-insecure

---

关于您的问题：您不能阻止用户重新登录。但是，一旦用户进入登录页面，您就可以检查他/她是否已经登录，然后重定向到仪表板。