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.
Users can still browse your website because cookies are not cleared when you call FormsAuthentication.SignOut() and they are authenticated on every new request. In MS documentation is says that cookie will be cleared but they don't, bug?
Its exactly the same with Session.Abandon(), cookie is still there.
You should change your code to this:
FormsAuthentication.SignOut();
Session.Abandon();
// clear authentication cookie
HttpCookie cookie1 = new HttpCookie(FormsAuthentication.FormsCookieName, "");
cookie1.Expires = DateTime.Now.AddYears(-1);
Response.Cookies.Add(cookie1);
// clear session cookie (not necessary for your current problem but i would recommend you do it anyway)
SessionStateSection sessionStateSection = (SessionStateSection)WebConfigurationManager.GetSection("system.web/sessionState");
HttpCookie cookie2 = new HttpCookie(sessionStateSection.CookieName, "");
cookie2.Expires = DateTime.Now.AddYears(-1);
Response.Cookies.Add(cookie2);
FormsAuthentication.RedirectToLoginPage();
HttpCookie is in the System.Web namespace. MSDN Reference.
Using two of the above postings by x64igor and Phil Haselden solved this:
1. x64igor gave the example to do the Logout:
You first need to Clear the Authentication Cookie and Session Cookie by passing back empty cookies in the Response to the Logout.
public ActionResult LogOff()
{
FormsAuthentication.SignOut();
Session.Clear(); // This may not be needed -- but can't hurt
Session.Abandon();
// Clear authentication cookie
HttpCookie rFormsCookie = new HttpCookie( FormsAuthentication.FormsCookieName, "" );
rFormsCookie.Expires = DateTime.Now.AddYears( -1 );
Response.Cookies.Add( rFormsCookie );
// Clear session cookie
HttpCookie rSessionCookie = new HttpCookie( "ASP.NET_SessionId", "" );
rSessionCookie.Expires = DateTime.Now.AddYears( -1 );
Response.Cookies.Add( rSessionCookie );
2. Phil Haselden gave the example above of how to prevent caching after logout:
You need to Invalidate the Cache on the Client Side via the Response.
// Invalidate the Cache on the Client Side
Response.Cache.SetCacheability( HttpCacheability.NoCache );
Response.Cache.SetNoStore();
// Redirect to the Home Page (that should be intercepted and redirected to the Login Page first)
return RedirectToAction( "Index", "Home" );
}
Sounds to me like you don't have your web.config authorization section set up properly within . See below for an example.
<authentication mode="Forms">
<forms name="MyCookie" loginUrl="Login.aspx" protection="All" timeout="90" slidingExpiration="true"></forms>
</authentication>
<authorization>
<deny users="?" />
</authorization>
The key here is that you say "If I type in a URL directly...".
By default under forms authentication the browser caches pages for the user. So, selecting a URL directly from the browsers address box dropdown, or typing it in, MAY get the page from the browser's cache, and never go back to the server to check authentication/authorization. The solution to this is to prevent client-side caching in the Page_Load event of each page, or in the OnLoad() of your base page:
Response.Cache.SetCacheability(HttpCacheability.NoCache);
You might also like to call:
Response.Cache.SetNoStore();
I've struggled with this before too.
Here's an analogy for what seems to be going on... A new visitor, Joe, comes to the site and logs in via the login page using FormsAuthentication. ASP.NET generates a new identity for Joe, and gives him a cookie. That cookie is like the key to the house, and as long as Joe returns with that key, he can open the lock. Each visitor is given a new key and a new lock to use.
When FormsAuthentication.SignOut() is called, the system tells Joe to lose the key. Normally, this works, since Joe no longer has the key, he cannot get in.
However, if Joe ever comes back, and does have that lost key, he is let back in!
From what I can tell, there is no way to tell ASP.NET to change the lock on the door!
The way I can live with this is to remember Joe's name in a Session variable. When he logs out, I abandon the Session so I don't have his name anymore. Later, to check if he is allowed in, I simply compare his Identity.Name to what the current session has, and if they don't match, he is not a valid visitor.
In short, for a web site, do NOT rely on User.Identity.IsAuthenticated without also checking your Session variables!
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>
This works for me
public virtual ActionResult LogOff()
{
FormsAuthentication.SignOut();
foreach (var cookie in Request.Cookies.AllKeys)
{
Request.Cookies.Remove(cookie);
}
foreach (var cookie in Response.Cookies.AllKeys)
{
Response.Cookies.Remove(cookie);
}
return RedirectToAction(MVC.Home.Index());
}
This Answer is technically identical to Khosro.Pakmanesh. I'm posting it to clarify how his answer differs from other answers on this thread, and in which use case it can be used.
In general to clear a user-session, doing
HttpContext.Session.Abandon();
FormsAuthentication.SignOut();
will effectively log out the user. However, if in the same Request you need to check Request.isAuthenticated (as may often happen in an Authorization Filter, for example), then you will find that
Request.isAuthenticated == true
even _after you did HttpContext.Session.Abandon() and FormsAuthentication.SignOut().
The only thing that worked was doing
AuthenticationManager.SignOut();
HttpContext.User = new GenericPrincipal(new GenericIdentity(string.Empty), null);
That effectively sets Request.isAuthenticated = false.
The code you posted looks like it should correctly remove the forms authentication token, so it is possible that the folders/pages in question are not actually protected.
Have you confirmed that the pages cannot be accessed before a login has occured?
Can you post the web.config settings and login code that you are using?
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
I just tried some of the suggestions here and while I was able to use the browser back button, when I clicked on a menu selection the [Authorize] token for that [ActionResult] sent me right back to the login screen.
Here is my logout code:
FormsAuthentication.SignOut();
Response.Cookies.Remove(FormsAuthentication.FormsCookieName);
Response.Cache.SetExpires(DateTime.Now.AddSeconds(-1));
HttpCookie cookie = HttpContext.Request.Cookies[FormsAuthentication.FormsCookieName];
if (cookie != null)
{
cookie.Expires = DateTime.Now.AddDays(-1);
Response.Cookies.Add(cookie);
}
Although the back function on the browser took me back and displayed the secured menu (I am still working on that) I was not able to do anything that was secured in the app.
Hope this helps
I've tried most answers in this thread, no luck. Ended up with this:
protected void btnLogout_Click(object sender, EventArgs e)
{
FormsAuthentication.Initialize();
var fat = new FormsAuthenticationTicket(1, "", DateTime.Now, DateTime.Now.AddMinutes(-30), false, string.Empty, FormsAuthentication.FormsCookiePath);
Response.Cookies.Add(new HttpCookie(FormsAuthentication.FormsCookieName, FormsAuthentication.Encrypt(fat)));
FormsAuthentication.RedirectToLoginPage();
}
Found it here: http://forums.asp.net/t/1306526.aspx/1
This started happening to me when I set the authentication > forms > Path property in Web.config. Removing that fixed the problem, and a simple FormsAuthentication.SignOut(); again removed the cookie.
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).
I just had the same problem, where SignOut() seemingly failed to properly remove the ticket. But only in a specific case, where some other logic caused a redirect. After I removed this second redirect (replaced it with an error message), the problem went away.
The problem must have been that the page redirected at the wrong time, hence not triggering authentication.
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.
Just try to send a session variable when you press log in.
And on the welcome page, first check whether that session is empty like this in the page load or in the Init Event:
if(Session["UserID"] == null || Session["UserID"] == "")
{
Response.Redirect("Login.aspx");
}
I wanted to add some information to help understand the problem. Forms Authentication allows for storing user data either in a cookie, or in the query string of the URL. The method your site supports can be configured in the web.config file.
According to Microsoft:
The SignOut method removes the forms-authentication ticket information
from the cookie or the URL if CookiesSupported is false.
At the same time, they say:
One of the HttpCookieMode values that indicates whether the
application is configured for cookieless forms authentication. The
default is UseDeviceProfile.
Lastly, regarding UseDeviceProfile, they say:
If the CookieMode property is set to UseDeviceProfile, the
CookiesSupported property will return true if the Browser for the
current Request supports both cookies and redirecting with cookies;
otherwise, the CookiesSupported property will return false.
Piecing this all together, depending on the user's browser, the default configuration may result in CookiesSupported being true, which means the SignOut method doesn't clear the ticket from the cookie. This seems counter-intuitive and I don't know why it works this way -- I would expect SignOut to actually sign the user out under any circumstances.
One way to make the SignOut work by itself is to change the cookie mode to "UseCookies" (i.e. cookies are required) in the web.config file:
<authentication mode="Forms">
<forms loginUrl="~/Account/SignIn" cookieless="UseCookies"/>
</authentication>
According to my tests, doing this makes SignOut work by itself at the cost of your site now requiring cookies to function properly.
For me, the following approach works. I think if there is any error after the "FormsAuthentication.SignOut()" statement, SingOut doesn't work.
public ActionResult SignOut()
{
if (Request.IsAuthenticated)
{
FormsAuthentication.SignOut();
return Redirect("~/");
}
return View();
}
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.)
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.
For MVC this works for me:
public ActionResult LogOff()
{
FormsAuthentication.SignOut();
return Redirect(FormsAuthentication.GetRedirectUrl(User.Identity.Name, true));
}
Be aware that WIF refuses to tell the browser to cleanup the cookies if the wsignoutcleanup message from STS doesn't match the url with the name of the application from IIS, and I mean CASE SENSITIVE. WIF responds with the green OK check, but will not send the command to delete cookies to browser.
So, you need to pay attention to the case sensitivity of your url's.
For example, ThinkTecture Identity Server saves the urls of the visiting RPs in one cookie, but it makes all of them lower case. WIF will receive the wsignoutcleanup message in lower case and will compare it with the application name in IIS. If it doesn't match, it deletes no cookies, but will report OK to the browser. So, for this Identity Server I needed to write all urls in web.config and all application names in IIS in lower case, in order to avoid such problems.
Also don't forget to allow third party cookies in the browser if you have the applications outside of the subdomain of STS, otherwise the browser will not delete the cookies even if WIF tells him so.
I have a page where I need to check for the presence of a cookie and then perform a redirect.
I have the code written (ASP.NET) to detect the cookie and perform a redirect. Pseudo-code:
HttpCookie myCookie = Request.Cookies.Get("theCookie");
if(myCookie == null)
{
myCookie = new HttpCookie("theCookie","myValue")
response.Redirect("page.aspx"); //Redirect to check for the presence of the cookie
}
More code...
When the user has cookies enabled, this approach works fine. When they have cookies disabled, however, they wind up stuck in an infinite loop (the page attempts to create the cookie, redirects, sees no cookie, then redirects again, ad infinitum). Most human users are probably going to be OK, but this will probably do a number on the site's SEO ratings.
I've wracked my brain for solutions, and since cookies are out of the question, that leaves viewstate and querystrings.
Because I've got to do a redirect, I think I'm stuck with querystrings. The problem is in order to detect whether a page has already been hit, I need to append a querystring to prevent the redirect from kicking in again.
Can anyone think of a way to accomplish this (preventing a redirect) without using cookies, viewstate, or querystrings? I think the answer is probably no...
Using a querystring in the manner you have described is the correct solution.
EDIT: looks like bad idea - query string is the approach. Keeping for reference: local storage as well as script can be disabled, so it needs to be considered when designing any client side detection logic.
You can also try to use local storage in browser to prevent infinite redirects. It will allow you to keep url clean from "?isCookie=true" query string. Note that you need JavaScript enabled for that. If you worried about cookies you should be worried about JavaScript disabled too.
What I wound up doing (in case someone else tries this) was using a couple of tricks:
Set up an ASP.NET hidden field control with its value set to false (default - cookies are disabled)
Used client-side script to check whether cookies are enabled
If the cookie gets set, cookies are enabled. In this case I use a jQuery call to change the value of the hidden field from false to true
Server-side, if the value of the hidden field is true, the page does the redirect. Otherwise, it just continues processing the page.
If the user has Javascript disabled, the value of the hidden field remains false, so the page is still rendered only once.
Thanks for letting me talk through it and getting me thinking!
I have a page that when you press 'log out' it will redirect to the login.aspx page which has a Page_Load method which calls FormsAuthentication.SignOut().
The master page displays the 'log out' link in the top right of the screen and it displays it on the condition that Page.User.Identity.IsAuthenticated is true. After stepping through the code however, this signout method doesn't automatically set IsAuthenticated to false which is quite annoying, any ideas?
Page.User.Identity.IsAuthenticated gets its value from Page.User (obviously) which is unfortunately read-only and is not updated when you call FormsAuthentication.SignOut().
Luckily Page.User pulls its value from Context.User which can be modified:
// HttpContext.Current.User.Identity.IsAuthenticated == true;
FormsAuthentication.SignOut();
HttpContext.Current.User =
new GenericPrincipal(new GenericIdentity(string.Empty), null);
// now HttpContext.Current.User.Identity.IsAuthenticated == false
// and Page.User.Identity.IsAuthenticated == false
This is useful when you sign out the current user and wish to respond with the actual page without doing a redirect. You can check IsAuthenticated where you need it within the same page request.
A person is only authenticated once per request. Once ASP.NET determines if they are authenticated or not, then it does not change for the remainder of that request.
For example, when someone logs in. When you set the forms auth cookie indicating that they are logged in, if you check to see if they are authenticated on that same request, it will return false, but on the next request, it will return true. The same is happening when you log someone out. They are still authenticated for the duration of that request, but on the next one, they will no longer be authenticated. So if a user clicks a link to log out, you should log them out then issue a redirect to the login page.
I remember having a similar problem and I think I resolved it by expiring the forms authentication cookie at logout time:
FormsAuthentication.SignOut();
Response.Cookies[FormsAuthentication.FormsCookieName].Expires = DateTime.Now.AddYears(-1);
Why are you executing logout code in the login.aspx?
Put this code in e.g. logout.aspx:
FormsAuthentication.SignOut()
Session.Abandon()
FormsAuthentication.RedirectToLoginPage()
HttpContext.Current.ApplicationInstance.CompleteRequest()
return
IsAuthenticated will be false in login.aspx.
Login and logout code are now separated: Single Responsibility.
In your login.aspx Page_Load method:
if (!this.IsPostBack)
{
if (HttpContext.Current.User.Identity.IsAuthenticated)
{
FormsAuthentication.SignOut();
Response.Redirect(Request.RawUrl);
}
}
In one of my application when I am signIn with credentials , navigating to different forms in an application then i have copied one of my navigated form url then logout form the application. in the search tab i have paste the url the browser is navigating to the specific form in my application without login.
while checking the form authentication as page.User.Identity.IsAuthenticated getting as true even when we logout.The causes for this is while clearing the session on logout i have added
Response.Cookies[FormsAuthentication.FormsCookieName].Expires = DateTime.Now.AddYears(-1);
with this I am not getting that issue again and the flag page.User.Identity.IsAuthenticated getting as false when we are navigating to the different forms in an application without login.
Update
I got comments that my answer didn't work with many folks. I wrote this answer back in 2011 after tearing my hear. So I am pretty sure it solved the problem.
I started to research this 6 years old problem and came to this solution which I believe might be the proper way of deleting the cookies which is by creating them again but with expired dates.
This works for me
public virtual ActionResult LogOff()
{
FormsAuthentication.SignOut();
foreach (var cookie in Response.Cookies.AllKeys)
{
Response.Cookies.Remove(cookie);
}
return RedirectToAction(MVC.Home.Index());
}
I have the following code:
if (HttpContext.Current.Request.IsAuthenticated == false)
{
// this isn't reached so i know user is Authenticated
return;
}
FormsIdentity fIdentity = HttpContext.Current.User.Identity as FormsIdentity;
string[] delimitedUserData = fIdentity.Ticket.UserData.Split('|');
// but at this point delimitedUserData.Length is 0
Any ideas on what would cause the authentication ticket to be valid yet the UserData is gone?
My program usually works just fine and all the UserData is readily accessible. But every once in awhile I get into this state where the UserData is not there.
The ticket is stored in a cookie. What happens in your code when you access a page just after the cookie has expired?
Also note that User.Identity.IsAuthenticated returns true out of the box, so that property is perhaps not the best thing to test on?
By itself, FormsAuthentication doesn't put anything into your UserData. It'd be worth putting a breakpoint near where you handle ticket creation (and the creation of your UserData) and tracing through the path it takes.
As your bug is intermittent, it'll probably be hard to force it to trigger. A place to start could be tracing through how it handles the cookie expiring, or when a cookie is invalid.
If you're using Firefox, I recommend using the "Add N Edit Cookies" plugin: https://addons.mozilla.org/en-US/firefox/addon/573
Not sure if this is the best approach as I'm still fairly new to asp.net, but the way that I do this on the login is to set a session value that I can check in later pages - that way, if the cookie is missing, I should not be able to get the value back so I can transfer to the login page.
So, directly after the login (in the _LoggedIn event), I do:
// write ClientID to the session
Session.Add("ClientID", lClientID);
then on the load of each page behind the login, I do:
if (User.Identity.IsAuthenticated == false || Convert.ToInt32(Session["ClientID"]) == 0)
{
Server.Transfer("Login.aspx");
}
So far, it's worked pretty well for me.
i am searching for the same issue and find the problem that, i used
"FormsAuthentication.RedirectFromLoginPage" to add cookie. i changed into "response.cookies.add". and its working.