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Integrated Windows Authentication - Logout

I am attempting to use Integrated Windows Authentication on IIS for an MVC web app. The original hope was that the user would be logged in automatically using the current Windows user credentials. I am running into the issue where the user is always prompted to enter user name and password. I have decided that we can live with this. However, I have also noticed that the user can enter any valid domain credentials...it's not limited to the currently logged in machine. But if this is the case, I need to provide a logout button, so the user can be switched if necessary.
Everything I can find on this issue, logging out in Windows Authentication, says you cannot do it because it pulls the credentials from the machine login. But it's obviously not doing that in my case, because I can enter any valid credentials and log in successfully. So a user could be logged onto the machine as user X, and then, when prompted, log into the web app as user Y. Am I to understand that, under Windows Authentication, there's no way to address this?

Are you sure you selected Windows Authentication While creating the Project? Confirm that and if yes, proceed to check your web.config that application authentication is set to windows.

How to get current windows username and disable the credentials prompting?

I have a C#.NET 4.0 application running under IIS 7 on Windows Server 2008 with IIS7 server. The application will run in the company intranet that automatically grabs the logged-in Windows username of the person viewing the page without being prompted to enter credentials when the page loads. Now i'm facing 2 problems:
1) Currently, the apps returns the production server name (eg: XYZ\sam) that the application located at. I want to get the current logged on username (eg: ABC\sam). It works fine at localhost but not at production server.
I've enabled <authentication mode="Windows" /> at web.config , enabled windows authentication and disabled anonymous authentication at IIS.
I've tried Page.User.Identity.Name, System.Web.HttpContext.Current.User.Identity.Name, System.Security.Principal.WindowsIdentity.GetCurrent().Name, and others but still failed to get the right name. How to get the current windows logged on user?
2) When I want to access the application, it keeps prompting out a windows for username and password. If I ignore it, it will prompt out
401 - Unauthorized: Access is denied due to invalid credentials. You
do not have permission to view this directory or page using the
credentials that you supplied.
How i gona fix it?

For question 1, it cannot retrieve the logged in username because the server is domain server. It works after transfer from workgroup to domain.
For question 2, it works fine(no pop out credential) if I access with the server name (eg:servername/appsname). But it will ask for credential if I use ip (eg:xxx.xx.xx.x/appsname) and didn't setup the tools internet options. Factor still not known.

For your 2 problem, to log automatically, you have to set it on the browser, for my experience, i have done this in IE: https://superuser.com/questions/537416/how-to-make-internet-explorer-automatically-login-in-a-certain-domain

Get Windows user credentials with windows authorization disabled in IIS

Is it possible to grab a users windows credentials (i.e. username) without having windows authentication enabled in IIS? With windows auth disabled the code below returns either NT AUTHORITY or IIS APPPOOL\ASP.NET v4.0 depending on if impersonation and anonymous authentication are enabled or not.
System.Security.Principal.WindowsIdentity.GetCurrent().Name.ToString();
I am converting an asp.net web application that is using forms authentication to custom authentication. Basically if a user is connecting from outside the network I force a credential check whereas if they are connecting from within the network I would like to be able to just grab their windows username. The internal portion works when I turn on windows authentication but I get the popup login box when testing outside of the network. I either need to disable windows authentication for non local connections or figure out how to get the windows username with windows authentication disabled. Any suggestions? (The other alternative i thought of was splitting the application in two and having separate authentication modes for each but I'd like to avoid this).
-I have also tried:
System.Web.HttpContext.Current.User.Identity.ToString();
System.Threading.Thread.CurrentPrincipal.ToString();

something like this is actually (kind of) possible using Active Directory Federated Services. In the event of a windows user from inside the network they can be configured to use their account details. For external users, they can be redirected to a page that will require them to log in.
However. This is very heavy-duty and an extreme pain in the..neck to implement and is really only applicable to enterprise solutions that have the resourses to use this kind of solution. Otherwise, I'd say go with the 2 site approach.

Simple answer is no.
Best solution is to create 2 sites. One for internal users that user windows authentication, one for external user that user forms authentication but authenticate against AD. You can make users always go to external site by default and then redirect based on their IP. That is redirect intranet users to internal user.

Windows Authentication not working on server

I'm developing a website in ASP.NET and C#.
I've created the website so when a user goes to the site, his windows client username is read out with:
System.Security.Principal.WindowsIdentity.GetCurrent().Name.ToString();
and then I lookup his username in the db and create a user object with all necessary data (team, name, permission level, role, ...) from the return data.
Then I keep this object in a session var until the user logs out.
This was working like a charm locally but now that I've deployed to the server I get defaultAppPool for every user.
What am I doing wrong?
In my web.config file I have:
authentication mode="Windows"
I have to admit this is the first time that I'm doing the deploying myself and everything went smoothly except for this.

As you've discovered, System.Security.Principal.WindowsIdentity.GetCurrent() gives you the identity of the application pool.
You should be using HttpContext.Current.User.Identity.

Windows authentication and IIS
If you select Windows authentication for your ASP.NET application, you also need to configure authentication within IIS. That’s because Windows authentication is delegated back to IIS. IIS gives you a choice of four authentication methods:
If you select anonymous authentication, IIS does not perform any authentication. Anyone is allowed access to the ASP.NET application.
If you select basic authentication, users must provide a Windows username and password to connect. This information is sent across the network in clear text, making basic authentication dangerously insecure on the Internet.
If you select digest authentication, users must still provide a Windows username and password to connect. However, the password is hashed before being sent across the network. Digest authentication requires that all users be running Internet Explorer 5 or later and that Windows accounts be stored in Active Directory.
If you select Windows integrated authentication, passwords never cross the network. Users must still have a Windows username and password, but either the Kerberos or challenge/response protocols are used to authenticate the user. Windows-integrated authentication requires that all users be running Internet Explorer 3.01 or later.

Get current user identity as :
var userWinId = HttpContext.Current.User.Identity as WindowsIdentity;

Use
System.Web.HttpContext.Current.User.Identity.Name
instead of
User.Identity.Name
or
System.Security.Principal.WindowsIdentity.GetCurrent().Name

WCF: Windows or UserName authentication in one endpoint

We are implementing the following log on mechanism for our 3-tier application:
User launches the client application and -
authenticates using her Windows session credentials (Active Directory)
or enters her AD credentials if another user is already logged on to this Windows session
or enters her user name and password if the computer is not on the AD domain.
I.e. something like the SQL Server Management Studio log on box (+point 2. above).
The solution we came up with is having two endpoints, with two system bindings (one with Windows, the other with UserName client credential type).
I was wondering if there's a way of having just one endpoint with a custom binding that would magically allow the mixed authentication (either Windows or UserName)?
Also, why is it a bad idea?
Thanks!