User gets automatically logged out 1-2 mins after being logged in ASP.NET

Question

I've implemented the Login button as following:

                FormsAuthenticationTicket ticket = new FormsAuthenticationTicket(u.UserID.ToString(), true, 2880);
                string encTicket = FormsAuthentication.Encrypt(ticket);

                HttpCookie cookie = new HttpCookie(FormsAuthentication.FormsCookieName, encTicket);
                cookie.Expires = DateTime.Now.AddMinutes(2880);
                Response.Cookies.Add(cookie);
Response.Redirect("/index.aspx");

And this is my web config:

   <authentication mode="Forms">
      <forms loginUrl="Login.aspx" defaultUrl="Index.aspx" slidingExpiration="true" timeout="2880" />
    </authentication>

My question is: when I deploy my web application to the hosting, once I'm logged in, I scrool around few pages in users directory, and almost immediately after 30 secs - 1 min I get logged out and redirected to the login page so that I can relog again. Why is this happening ??? I've tested it on my local machine and it works just fine?!?!

Can someone help me out with this ??

Answer 1

Are you hosting on a web farm?

If so, you are logging into one server and when you are redirected to a different server it can't decrypt your authentication ticket. All of the machine keys have to be the same across each of your web servers. See How To: Configure MachineKey in ASP.NET 2.0