Someone

<?php
session_start();
if(isset($_SESSION['username'])){
	echo "You are logged in.";
        echo '<script>window.location="login_success.php"</script>';
}else{
	echo "You're not logged in.";
	unset($_SESSION['username']);
	unset($_SESSION['length']);}
?>
<body bgcolor="black" alink="green" vlink="green" text="green">
<title>Nevercracker Server</title>
<h1>Nevercracker Server</h1><hr>
<BR><a href="main_login.php">Login</a>
<BR><a href="register.php">Register</a>