<?php

session_cache_expire( 5 );
session_start(); 
$inactive = 300;
if(isset($_SESSION['start']) ) 
{	
	$session_life = time() - $_SESSION['start'];	
	if($session_life > $inactive)
	{		
		session_destroy();
		header("Location: index.php");		
	}
}
$_SESSION['start'] = time(); 
if($_SESSION['valid_user'] != true)
{
	session_destroy();
	header('Location: index.php');
}

?>