I want to prevent users from accessing the main page of my website since they have no reason whatsoever unless they authenticate through steam. So I set up a PHP script that redirects you to the login page if you are not signed in. And redirects you away from the login page if you are already signed in.
However this is giving me SEO issues as webcrawlers see a 302 redirect and don't do anything.
What php variable checks if its a webcrawler?