title: How to correctly log out of form Authentication
body: <p>Currently my ASP.Net webform  uses <code>FormsAuthentication.SignOut();</code>
  Problem is this:</p>
  
  <p>User goes to loginpage and logs in and gets redirected to page A</p>
  
  <p>In page A he clicks on logout and gets redirected to </p>
  
  <p>loginpage. </p>
  
  <p>In login page load event I have FormsAuthentication.SignOut().</p>
  
  <p>I assume this will destroy the authentication cookie.  </p>
  
  <p>But user can a still use browser's back button to go to the A page!</p>
  
  <p>Is this accepted? and if not what the best way to fix </p>
  
  <p>===============
  I tried the following but still No luck:</p>
  
  <pre><code>Response.Cache.SetExpires(DateTime.UtcNow.AddMinutes(-1));
  Response.Cache.SetCacheability(HttpCacheability.NoCache);
  Response.Cache.SetNoStore();
  </code></pre>
  
  <p>Question itself is duplicate but none of the provided answers in the other question works.  So the is not a working answer.</p>
  
  <p>Also these do not work:</p>
  
  <pre><code>Response.Cache.SetExpires(DateTime.UtcNow.AddMinutes(-1));
          Response.Cache.SetCacheability(HttpCacheability.NoCache);
          Response.Cache.SetNoStore();
          FormsAuthentication.SignOut();
          Session.Abandon();
  </code></pre>
  
  <p>Also tried  FormAthentcation.RedirectToLoginPage </p>
  
  <p>Still back button works.</p>
  
  <p>Update: I found a workaround but it will only work if the browser backbutton cause ANY form/page event be fire. Do you know if backbutton fires any form event?</p>