PHP Login Painel

<?php
        session_start();

    if(!isset($_SESSION["id"]) || !isset($_SESSION["username"])){
        header("Location: index.php");
    }else{

    }
?>

<html>
    <head>
    <title> Login Pluz VS</title>
    <meta charset="UTF-8">
    </head>

    <body>
        <a href="logout.php"> Logout </a>
    </body>


</html>