Windows Authentication Timeout - asp.net

How can you suspend access to a user session after a specified interval of inactivity when using Windows Integrated Security for an ASP.NET MVC Website?

When using Kerberos for authentication Internet Explorer (IE) will continue sending the same credentials for each subsequent request to the server until one of two things happens:
   a) The user closes their browser.
   b) The server refuses the credentials with a 401 status code.
This behavior is KB 264921.
If we want to simulate a session than we have to implement the following steps:
Create a sliding expiration cookie for the duration of the session.
Check for that cookie for every request: begin_request or global filters. If the cookie is missing return a 401 status code for that specific request.
Next request will trigger the authentication prompt.
I was hoping someone else having a better ideea, this one feels kind of hacky.

Related

MVC manage session

I am using an MVC app to manage authentication. The issue I have is with chrome because it never actually kills the session because it runs in the background after it closes by default. I do not want to enforce all the end users to change this setting because then it will kill hangouts etc.. So I am wondering if I can use any standard web.config setting to handle this or do I need to make an ajax polling interval to keep updating the cookie expiration?
The ASP.NET session consists of 2 components the client-side http session cookie and the server's session storage provider. Suppose user has SessionId 1. If you delete session 1 from the server, the user returns and a new session is created with SessionId 1. If the user deletes the session cookie, the server keeps running session 1.
What you're asking for is generally not possible. There's no way you can force a user to send a request to your server when they are exiting your site or the browser. There is the javascript beforeUnload event which in some situations would allow you to send a request to /sign-off in some situations. The obvious limiter is no network access = no message.
The standard resolution for orphaned sessions is for session scavenging policy to clean them up. Some developers choose to use persistent storage to eliminate scavenging altogether such that a shopping cart would never disappear.
The only reasonable solution (which is still overkill) that would reach your goals. You use SingalR for a persistent connection of the user to the server and you ping them from the server. If the connection fails to respond you abandon the session. This will be a fragile process and if you don't make very very sure the user is disconnected you will have lots of support calls from users wondering why they are continuously logged out while browsing your site on cell phone.

Worklight keeps HTTP request active when user is logged out

I have an issue with Worklight 6.1. I will describe the scenario below:
User logs in the app and a new session is created for him. Then he stays inactive for some time until the session times out. When clicking on a button, an HTTP request is performed towards an HTTP adapter. However the Worklight server (Liberty) sees that there is no active session for this user and returns the appropriate response that the user is logged out and the user is redirected to the login page. This is correct up to here.
When the user logs in again and is redirected to the landing page, the previous request seems to have been cached and is performed resulting in an error as the necessary information is not yet available. How can I prevent this request from occruring when the user re logs in?
Thank you.
it's not possible to prevent the original request from re-sending after authentication.
The logic of the authentication and the logic of the application are separated and the result of a successful login will be the invocation of the original failed invocation.
What you can do is add to the adapter procedure implementation the logic that makes sure all the information is available, and if not - send an empty response to the client and in the client do whatever you want to do when the data is missing.
This should be done for all the procedures that rely on the session state.

are cookies getting generated every time we visit website?

I am developing session management for our Web-server. Below are steps I am following.
Very first time user comes to our server, We authenticate him based on username:password
provided and generate/set secure-cookie.
For subsequent request web-client will send same cookies back to us and we will validate
it.
If cookie is valid then we serve the response. If cookie is invalid then we check
if authorization credentials are present and try to authenticate user and again
generate/set secure-cookie
If cookie is not valid and no authorization credentials are present then send 401.
With cookie we are also setting expiry time. This mainly for inactivity timeout.
I want to know if I should regenerate cookie for subsequent request or not.
what will be a good design to generate or not to generate.
If we don't generate then how we can keep user logged in ?
You need to provide sliding expiration. For example you define an idle timeout of 5 min, then when the user performs a request in the last two minutes, you deploy the same cookie with a extended expiration.
ASP.NET uses this technique.

How does ASP.NET WebAPI using IIS store my users authentication state?

I have an asp.net Web Api 2 / Identity 2 application that requires a user to be authenticated. The authentication works but I notice that when I restart my local development machine and try to access a method that requires authentication then I get a failure.
As my application is unchanged from the asp.net sample then I think it uses cookies to store user data on the client. Where and how does the Server or IIS store information on which users have authenticated? Does it do this just the once or on every HTTP? Is there a difference between my using Token or cookie authentication in the way that the authentication and also authorization is checked on the server?
I think you are misunderstanding how authentication works with ASP.Net. As an example, let me show you some cookie details for a site of mine that uses Identity (note the token is actually in the cookie, the two are not mutually exclusive concepts):
Name __RequestVerificationToken
Value afeILhaIvRr56jXXXXXXXXXXX
Host site.azurewebsites.net
Path /
Expires At end of session
Note that the cookie, by default, expires at the end of your session. That means when you restart your development machine, your cookie is expired and your token is no longer valid.
In particular I have read that with token authentication then there is no need for continual re-authentication every time a request is made to the server
You need to understand that HTTP is a stateless protocol. Each request happens in a vacuum, and therefore you need to pass some data back to the server so that it can tell that the person who authenticated with Request A is really the initiator of Request B. Almost always, that piece of data is from a cookie. So, every request does indeed re-authenticate, and typically with a token in a cookie.
The only piece of data about your session that is stored on the client is the cookie (unless you are doing something atypical). The rest is on the server. How it is stored can vary:
Inproc: Easiest to setup, sessions are stored in process. So when your server or app pool is restarted, that data disappears
State Server Mode: Sessions are stored in process, but outside of the ASP.Net worker process, so the application can be restarted without losing session data
SQL Server: Unsurprisingly, this stores data in a database. Very resilient, but more work to setup. Also your best option if you are on a web farm.
ref: http://msdn.microsoft.com/en-us/library/vstudio/ms178586(v=vs.100).aspx
Expanding on the great answer by Chris, I would like to add that there are two possible models here. In forms authentication (which is the default membership type for asp.net) the cookie can either store authentication information and then it's called a ticket or the information can be stored in session, with the cookie being a simple identifier for "reconnecting" the authenticated session with the requesting client on each subsequent request.
This "reconnecting" happens in the Application_AuthenticateRequest method of the global.asax. If you are using the default forms authentication storage, i.e. an SQL DB created for you by the framework, the reconnection will be done automatically. If you are using a custom authentication store (like accessing active directory yourself or a custom users table structure) you can override the the method and reconnect the authenticated session using your own implementation. In any case, the authentication data is populated in the User.Identity object's different properties. From that point, if you use the [Authorize] attribute, the framework accesses the object to check if the user is indeed authenticated and authorized.
I any case, the authentication information is tied to both the cookie and the session. Assuming your session is InProc, like Chris said, when the session is lost (through timeout, app pool recycle or restart of the dev machine) the server-side of the session is lost and your authentication / session cookie is replaced by a new one on the next request.
EDIT: Ohh... and one more side comment. Make sure you distinguish between authentication and authorization. The client is not re-authenticated on each request. Authentication is the process of providing your credentials and being identified by the server. Authorization is, now that the server has verified who you are, on each request it checks if you are authorized to access the resource you are requesting.
The server doesn't store information about who's authenticated and who isn't. Depending on your authentication mechanism (forms, tokens?), typically, when a user logs in, the server will return some form of authentication token that the client should pass back to the server on each API call.
Without knowing more about your configuration, it's difficult to explain why when you restart your server you have to re-authenticate, it sounds like the authentication token generated by the server is invalidated on restart.
Where and how does the Server or IIS store information on which users have authenticated?
IIS does not store state based on cookie authentication. Everything is determined based on the request. Either a request has the correct encrypted information, or it doesn't. If you look at a default Forms authentication in ASP.NET, you will find a cookie called .ADUAUTH ... this cookie has all the information to authenticate the request. If the cookie is half expired, it will be reset, but that's all IIS does.
Does it do this just the once or on every HTTP?
Every HTTP request is unique, so yes, per HTTP request.
Is there a difference between my using Token or cookie authentication in the way that the authentication and also authorization is checked on the server?
It's always checked on the server: To find out more, check out: How ASP.NET Security Works: http://msdn.microsoft.com/en-us/library/ks310b8y.ASPX
I think my answer could be a little contradicting to all of the above.. But I think If I understand right..
IIS stores inside the memory space of the ASP.NET worker process, i.e the session data in the RAM.
The storing of authentication state depends on the authentication model you are using. For example: if you are using the Federated authentication, through ADFS, then when a user loads your web page he is required to sign in providing his credentials. The ADFS then sets the authentication token which is stored in the session data, the session id is stored as cookies in user's browser. The server has the mapping of Session Id to its session data.
Now the user is authenticated. The ADFS looks for authentication token to mark a user as authenticated.
When you restart the server, the session data is lost as the data is stored in RAM.
There are ways to handle this, there are 3 types of session storage:
1. InProc (Stored in memory space of ASP .NET Worker process - RAM)
2. State Server (Stored out side of ASP .NET worker process, like on cloud Azure storage)
3. SQL Server session storage (Stored in SQL server)
I think you are adopting 1, because of which you encounter the problem.
In cases 2 and 3, the session is not lost when you restart the server.
Several things --
Token based authentication is not really authentication. It is just issuing you a unique token (can be a guid, unique string, etc) and then associating it with something (like your IP address) and saving that association server side (in a database?). Now whenever you use that token, from the client app, the server checks the association already stored and serves or denies or request.
In many ways, it is very similar to using Cookies to maintain authentication. Only, token-auth was designed more for web services operation than for UIs.
In short: Out of the box, the membership provider will run it's authentication method and upon success, it will create an auth ticket/token/cookie that will be stored from the site. In addition to this, there is a session cookie that is stored with the site as well. When you make a page request, it'll pull these things and use them to determine whether or not you are already authenticated. If it finds the ticket and sees that it is still good, it'll allow access.
When you restart your local environment, the session and it's information is destroyed which is why you have to log in again.
There is an entire pipeline in the framework that makes all of this stuff happen (having to do with authentication, authorization, and identity) and there are number of ok articles on the interwebs explaining this, but imo, they're almost all incomplete or hard to follow. If you want a great soup-to-nuts explanation, PluralSight.com has some training videos that will deconstruct and explain the entire pipeline for you. Understanding the pipeline can help you implement your own custom authentication, and I highly recommend it.

How does IIS recognize different sessions in .NET?

Suppose I have logged into an application which is running from IIS. Now I haven't logged out, but closed the browser. And when I'm accessing the application again, it defaults to the login page. How does IIS recognize that it is a new request and redirects the user to the login page?
I have another question. Suppose if I'm not closing the browser, which I used when I logged in. I'm opening the new browser to request a page from same application. IIS recognizes that it's a new request to the application and redirects the user to login page. Why does it not use the existing session or cookies which the first browser uses?
Please don't get irritated of my continuous questions... I am having huge confusion.
We say HTTP is a stateless protocol. Once the page is requested I have logged in. And the HTTP protocol connection will be terminated between IIS and browser, right? Then I am navigating to other pages in that logged in application. Now IIS recognises the user has logged in on this browser. But when I open a new browser and request that application, how does IIS recognises it is a new request? Since the HTTP protocol is disconnected, how does it work in the first case?
As you've correctly said, HTTP itself is stateless, and each request is technically separate from every other. Sessions, as used by web sites, are a workaround for that. What happens, normally, is that the server stores whatever info it cares to maintain between requests (like the logged-in user's username and/or ID, for example), and assigns that information an ID (called a "session ID"). It then tells the browser that session ID, in such a way that the browser can hand the ID back when it's time to make another request. If the browser plays its part and provides the session ID, then the stored information can be retrieved, updated, etc with each request, providing some degree of state even over a stateless protocol.
Sessions are usually implemented using cookies. That is, the server hands the browser a cookie with the session ID, and the browser hands back that same cookie with each request until the cookie expires or is otherwise forgotten. Some cookies (so-called "session cookies") aren't saved, and are forgotten when the browser is closed. A freshly opened browser doesn't have any session cookies to pass, so if the server uses session cookies to do sessions (which it should), it will consider the user not yet logged in and bounce them to the login page if they need to be logged in.
Session cookies will usually be shared between tabs in the same browser, and will sometimes even be shared by windows opened by "File > New Window" from an already running browser, because both of those cases will typically just be a part of that browser. But if you start the browser from the Start menu, or however your OS lets you start a program, it's a whole other process -- and session cookies are rarely shared between processes.
The server typically also only remembers sessions on its end for a limited time (anywhere from seconds to years, depending on the server and/or site settings) after each request that uses the session. If the browser passes a cookie that corresponds to a session the server no longer remembers, it'll act as if there's no session at all. Which, in cases where you have to log in, will again bounce to the login page.
There are cookies that are passed always no matter are you logged or not. They are mapped to session in IIS.
Check out the following articles. They might be helpful.
IIS Dropping Sessions
Session Management in ASP.NET

Resources