Question

By requiring users to have a session set and if it is not redirecting them using php header, am I securely keeping search engine crawlers from seeing my page content?

I don’t see how they would but I want to be positive.

Answer 1

Good crawlers will follow the redirect and not see the page content. Bad bots will still crawl the page. That is why you should always end execution of the script using exit() after sending out your redirect headers.

header('Location: /login.php');
exit();