I need a type of code to where if you type in the Url of a page in the Search bar, when you get to the page it doesn't allow you to see the content. But if you click a link on a website it will allow you to see the content!

Ex: instead of going to my forum by adress bar up top on browser it says: No, you must come to our main site first.

But if you click a link on my site you will get to go to the forum without the ...