FormsAuthentication.SignOut() does not log the use

Question

Smashed my head against this a bit too long. How do I prevent a user from browsing a site's pages after they have been logged out using FormsAuthentication.SignOut? I would expect this to do it:

FormsAuthentication.SignOut();
Session.Abandon();
FormsAuthentication.RedirectToLoginPage();

But it doesn't. If I type in a URL directly, I can still browse to the page. I haven't used roll-your-own security in a while so I forget why this doesn't work.

Answer 1

After lots of search finally this worked for me . I hope it helps.

public ActionResult LogOff()
{
    AuthenticationManager.SignOut();
    HttpContext.User = new GenericPrincipal(new GenericIdentity(string.Empty), null);
    return RedirectToAction("Index", "Home");
}

<li class="page-scroll">@Html.ActionLink("Log off", "LogOff", "Account")</li>

Answer 2

It could be that you are logging in from one subdomain (sub1.domain.com) and then trying to logout from a different subdomain (www.domain.com).

Answer 3

I am having a similar issue now and I believe the problem in my case as well as the original poster is because of the redirect. By default a Response.Redirect causes an exception which immediately bubbles up until it is caught and the redirect is immediately executed, I am guessing that this is preventing the modified cookie collection from being passed down to the client. If you modify your code to use:

Response.Redirect("url", false);

This prevents the exception and seems to allow the cookie to be properly sent back to the client.

Answer 4

I have been writing a base class for all of my Pages and I came to the same issue. I had code like the following and It didn't work. By tracing, control passes from RedirectToLoginPage() statement to the next line without to be redirected.

if (_requiresAuthentication)
{
    if (!User.Identity.IsAuthenticated)
        FormsAuthentication.RedirectToLoginPage();

    // check authorization for restricted pages only
    if (_isRestrictedPage) AuthorizePageAndButtons();
}

I found out that there are two solutions. Either to modify FormsAuthentication.RedirectToLoginPage(); to be

if (!User.Identity.IsAuthenticated)
    Response.Redirect(FormsAuthentication.LoginUrl);

OR to modify the web.config by adding

<authorization>
  <deny users="?" />
</authorization>

In the second case, while tracing, control didn't reach the requested page. It has been redirected immediately to the login url before hitting the break point. Hence, The SignOut() method isn't the issue, the redirect method is the one.

I hope that may help someone

Regards

Answer 5

Doing Session.abandon() and destroying the cookie works pretty good. I'm using mvc3 and it looks like the problem occurs if you go to a protected page, log out, and go via your browser history. Not a big deal but still kinda of annoying.

Trying to go through links on my web app works the right way though.

Setting it to not do browser caching may be the way to go.

Answer 6

Are you testing/seeing this behaviour using IE? It's possible that IE is serving up those pages from the cache. It is notoriously hard to get IE to flush it's cache, and so on many occasions, even after you log out, typing the url of one of the "secured" pages would show the cached content from before.

(I've seen this behaviour even when you log as a different user, and IE shows the "Welcome " bar at the top of your page, with the old user's username. Nowadays, usually a reload will update it, but if it's persistant, it could still be a caching issue.)