Restricting access of URL from Address bar

Hi,
I have an application where in the User Authentication is from the AD useing Directory services.
If i type in the address of a valid page from the application into the Address Bar, it throws me to the Login Page.
However if i am logged in and i type in the address of a valid webpage, the application takes me to the page. Is there any way that this can be restricted.
If i type in the URL into the address bar the application should throw me to the Home page of the application.
Can this be done without changing the code in each page?
 
Thanks in advance.
Hemangi
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