ASPX auth cookie expiration time is always 30 minutes

Question

I have set the the cookie expiration time to 1 month but when I look the expiration timeout of .ASPXAUTH cookie in browser it says 30 minutes ahead from now.

var ticket = new FormsAuthenticationTicket(1, "myname", DateTime.Now,
                                                        DateTime.Now.AddMonths(1), true, "test");
string ticketString = FormsAuthentication.Encrypt(ticket);
var cookie = new HttpCookie(FormsAuthentication.FormsCookieName, ticketString)
                 {
                     Expires = DateTime.Now.AddMonths(1),
                     Path = FormsAuthentication.FormsCookiePath
                 };
HttpContext.Current.Response.Cookies.Add(cookie);

Can you let me know why the above code is behaving so, I want to change the expiration time but it is always coming 30 minutes.

Answer 1

With the advice from the other answers I got to this link.

Apparently, in ASP.NET it checks the expiration in the Web.config and doesn't take the expiration from the cookie. So you need to add to the config file inside <system.web>:

<authentication mode="Forms">
  <forms
 name=".ASPXAUTH"
 loginUrl="Login.cshtml" //your login page
 defaultUrl="Default.cshtml" //your default page
 protection="All" //type of encryption
 timeout="43200" //a month in minutes
 path="/"
 requireSSL="false"
 slidingExpiration="true" //Every refresh the expiration time will reset
 cookieless="UseDeviceProfile" //Use cookies if the browser supports cookies
 domain=""
 enableCrossAppRedirects="false">
    <credentials passwordFormat="SHA1" />
  </forms>
</authentication>