I would like to control any URL manipulations and Authorization Bypass to my asp.net website by altering the URL. 

Right now user can access admin pages if he is able to guess the URL link.

For example - Admin link is (www.aspnet.in/admin)

user is able to manipulate and enter the admin link to change application level permissions. 

How to control that?

Hope you are able to understand.

Need a proper solution since my application has over 100 pages with dedicated admin page to control all users.

How can i best manage it?

Thanks.