forms authentication help

Hi All,
I secured my app with forms authentication. The issue is I have a folder(ALLAPPS) with different sub folders in it when the users click on the below link
http://MyTestServer/Default.aspx?req=/ALLAPPS/App_1
it is asking all users  for user id and password ( That's how it is supposed to work) .  but when I click on the below path I am able to access the app_1 folder with out Logging in how can I make sure that all the users will access APP_1 after  logging in only although they click on the below link.
http://MyTestServer/ALLAPPS/App_1/
...