Unable to get idsrv cookie to timeout instead of be persistent - identityserver3

Question

I have a problem where my idsrv cookie never seems to have a physical expiry time. So users on shared computers are logging in as each other because nobody appears to close their browser to kill this cookie.
Can someone please shed some light on what I should be doing?

Answer 1

You need to use persistent cookies to set the expiration, this will persist the cookie over browser sessions but also allow you to set the expiry. You don't mention which version of ASP.NET you're using but here's an example using aspnet core (the third parameter here must be true to persist the cookie):
var result =
await _signInManager.PasswordSignInAsync(model.Email, model.Password, true, true);
There are other ways to sign in but one way or another you'll have an overload that will allow you to set the persistent flag.
Then elsewhere you need to set the expiry when setting up cookie options you can specify the expiry time, e.g. if using Asp.Net Identity:
services.AddIdentity<ApplicationUser, IdentityRole>(
o => o.Cookies.ApplicationCookie.ExpireTimeSpan = TimeSpan.FromMinutes(30));
(Bear in mind that if you are on core and you upgrade to or use v2.0 you'll need to use services.ConfigureApplicationCookie instead, see here).
Of course this might not eliminate your users swapping machines within the expiration period but you can make the expiry small. What you can also do is use the SlidingExpiration flag alongside the expiry:
The SlidingExpiration is set to true to instruct the middleware to re-issue a new cookie with a new expiration time any time it processes a request which is more than halfway through the expiration window.
Meaning you can decrease the expiration time and so long as the user is still active they'll get new cookies. So the above code could be adjusted to:
services.AddIdentity<ApplicationUser, IdentityRole>(o =>
{
o.Cookies.ApplicationCookie.ExpireTimeSpan = TimeSpan.FromMinutes(10);
o.Cookies.ApplicationCookie.SlidingExpiration = true;
});