// login

<?php
$adminUsername = "username";
$adminPassword = "hash della password";
$usernameAdmin = htmlspecialchars($_POST['usernameAdmin']);
$passwordAdmin = htmlspecialchars(hash("sha256", $_POST['passwordAdmin']));
if(isset($usernameAdmin) && ($passwordAdmin) && ($usernameAdmin === $adminUsername) && ($passwordAdmin === $adminPassword))
{
	session_start();
	$_SESSION['login'] = "yes";
	header("Location: index.php");
}
else
{
	$counter = "0";
	session_start();
	$_SESSION['counter'] = $counter++;
	if($counter >= "4")
	{
		print"VAI VIA LAMER!!!";
	}
}
?>

// fine login

// il codice che va nelle pagine da proteggere

<?php
if(!isset($_SESSION['login']) && ($_SESSION['login'] != "yes"))
{
	die(header("Location: login.php"));
}
?>

//fine