destroying session??

[mailtome]

Hi
I have a simple login & logout script:

login.php
<?php
session_start();
$SESSION["username"]=$POST["username"];
?>

logout.php

<?php
session_start();
session_unset();
session_destroy();
?>

Now the problem:
When the user clicks the back button on the browser after the logout script, he appears to be logged in again.I think the browser caches the info. How can this be overcomed?? Please help.

[mihkel100]

You should have something like this

login.php

<?php
unset($ses);
session_start();
session_register('ses');
$ses['username']=$_POST['username'];
?>

logout.php

<?php
echo '<a href="?logout=1">Log out</a>';
 if(!$ses['username'] || $logout == 1){
        session_destroy(exit(header('Location: login.php')));
        }
?>