title: After logout the user should not be able to re enter into the site by typing the url of the internal pages in the address bar
body: <p>i m relatively new to C# and ASP.NET and I am having trouble designing an authentication system.</p>
  
  <p>I have created a website where the user has to login, after which he can access various pages in this site.  When the user clicks a logout link, he returns to the login page and is given the message "you have successfully logout."  Now how do I prevent the user from typing the URL of one of the internal pages, bypassing my authentication?  While working with PHP, I used <code>session_start()</code> and <code>ob_end_flush()</code> at the beginning and the end of each page to control authentication.  What is a similar model in ASP.NET?</p>
  
  <p>Also how do I include a <code>.cs</code> file from app_code folder to a <code>aspx.cs</code>?</p>