Use PHP to check if page was accessed with SSL

Be careful. On my IIS server, $_SERVER['HTTPS'] is not empty but has the value 'off'.

So i had to do

if (!isset($_SERVER['HTTPS']) || $_SERVER['HTTPS'] != 'on') {
    // no SSL request
}

You should be able to check that $_SERVER['HTTPS'] is set, e.g.:

if (empty($_SERVER['HTTPS'])) {
    header('Location: https://mywebserver.com/login.php');
    exit;
}