CODE EXAMPLE FOR PHP

localhost redirected you too many times. php

// On index.php

<?php
    session_start();
    include '../pages/YOURPHPFILE.php';
    if(!isset($_SESSION['username'])){header("location: login.php");}
?>

// If  you're using another file add this
<?php
    session_start();
    include '../pages/YOURPHPFILE.php';
    if(isset($_SESSION['username'])){header("location: index.php");}
?>