<?php

session_start();

if (isset($_SESSION['HTTP_USER_AGENT']))
{
    if ($_SESSION['HTTP_USER_AGENT'] !=
    md5($_SERVER['HTTP_USER_AGENT']))
    {
        /* Prompt for password */
        exit;
    }
}
else
{
    $_SESSION['HTTP_USER_AGENT'] =
    md5($_SERVER['HTTP_USER_AGENT']);
}

?>