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Prevent login with one user in different browser .NET Core

I want to create a login page that contain user and password with ASP.NET Core 5.
How can I prevent login with one user in different browser?

I would suggest at login you create a unique token that is stored on the server and passed back to the client as either an encrypted cookie value or if you are using Claims authentication as a claim. You then write a filter to test that the sent token matches the server side stored value on Authentication. You may want to store and update a datetime on the token - similar to a sliding cache item - so that you can expire the token.
When another browser or login occurs and the token is within a certain date then you can either suppress the login attempt or generate a new token which would logout the first browser user.
An example filter is shown below.
public class SignOnCheckerFilter : IAuthorizationFilter
{
public SignOnCheckerFilter (){}
public void OnAuthorization(AuthorizationFilterContext context)
{
bool checkOk = false;
if (context.HttpContext.User.Identity.IsAuthenticated)
{
//read cookie or claims
//check match
//if match success
checkOk = true;
}
//return if checkOk
if(checkOk) return;
//return forbidden result if invalid match (you could redirect the user to a logout page?)
context.Result = new ForbidResult();
}
}

Authentication/Authorization in ASP.NET Core using Enterprise SingleSignon page and Microsoft SignInManager

Presently I am working on an authentication issue in one of my ASP.NET Core(3.0) application.
To give some background, we have to use an Enterprise Single sign on page to authenticate the users. Once the user got authenticated it redirects back to our application along with user name in a HTTP header called "SM_USER". Then using that information we load corresponding Claim information from DB using Microsoft SignInManger. The application is working fine if the user is accessing the root but it couldn't able to access if they are trying to navigate a specific page directly, like http://website/Controller/Index.
I am suspecting that we may have implemented it wrongly so would like to know how should the below scenario to be implemented?
Our users first get authenticated using an enterprise Login Page(Single sign on) then redirected to our application. user information available on HTTP Headers and the corresponding claims information is available in our DB which we need to use for authorization purpose(we wanted to use Microrosoft SignInManger to load them).

I found the issue after researching it throughly so sharing here in case it useful for someone.
we observed whenever a user try to access a page if the user is not authenticated then it is redirecting Login page(Observed that decorating them with [Authorize] attribute is causing this), where We are using this Login page for local development purpose.
so when the user get redirected to login page and if the environment is not development then below code is executed on the Get method, which takes care of signing the user and creating UserPrincipal. Then after that we redirecting to the page the user requested.
if (!_signInManager.IsSignedIn(User))
{
string userName = HttpContext.Request.Headers["SM_USER"].ToString();
if (userName.Length > 0)
{
var user = await _userManager.FindByNameAsync(userName);
if (user != null)
{
var claimsPrincipal = await _signInManager.CreateUserPrincipalAsync(user);
await _signInManager.Context.SignInAsync(IdentityConstants.ApplicationScheme,
claimsPrincipal,
new AuthenticationProperties { IsPersistent = true });
if (string.IsNullOrEmpty(returnUrl)) //returnUrl is a parameter get passed by the system.
{
return RedirectToAction("<Action>", "<Controller>");
}
else
{
return Redirect(returnUrl);
}
}
}
}

Prompt user for additional information during an Open Id Connect event?

Using asp.net Core, Mvc and OpenIdConnect, is it possible to prompt an authenticated user for additional information during the ODIC authentication process, and then redirect back to the originally-desired page?
To give a concrete example: in our system one person, represented by an email address, can have multiple user ids that they may wish to operate under. Assume my email address is tregan#domain.com, and I have 3 user ids to choose from: treganCat, treganDog, treganMouse. When I hit a Controller action that is decorated with the [Authorize] attribute I first go through OpenIdConnect authentication, and one of the claims returned is an email address.
Using that email address, I want the application to prompt me to select the identity that I want to run under (treganDog, treganCat, or treganMouse).
From there, I want the application to take the user id that I selected, interrogate a database for the roles that go along with the selected user id, and load those roles as claims to my identity.
Finally, I want the application to send me on to my desired page (which is the protected Controller method that I originally attempted to visit).
Is this possible?
I'm using an Owin Startup class; the code below "works" except for the fictional line "var identityGuid = [return value from the prompt];" ("fictional" because it represents what I would like to occur, but in fact a series of redirects would be needed).
My example below uses the OnTicketReceived event, but that selection is arbitrary, I would be willing to do this in any event.
services.AddAuthentication(authenticationOptions =>
{
authenticationOptions.DefaultScheme = CookieAuthenticationDefaults.AuthenticationScheme;
authenticationOptions.DefaultChallengeScheme = OpenIdConnectDefaults.AuthenticationScheme;
})
.AddCookie()
.AddOpenIdConnect(openIdConnectOptions =>
{
openIdConnectOptions.Authority = Configuration["PingOne:Authority"];
openIdConnectOptions.CallbackPath = "/Callback";
openIdConnectOptions.ClientId = Configuration["PingOne:ClientId"];
openIdConnectOptions.ClientSecret = Configuration["PingOne:ClientSecret"];
openIdConnectOptions.ResponseType = "code";
openIdConnectOptions.Events.OnTicketReceived = (ticketReceivedContext) =>
{
var emailClaim =
ticketReceivedContext.Principal.Claims.FirstOrDefault(o =>
o.Type == ClaimTypes.Email);
string emailAddress = emailClaim.Value;
//here is where I would like to prompt the user to select an identity based on the email address
//the selected identity is represented by a guid
var identityGuid = [return value from the prompt];
var roles = new MyRepository(myContext).GetRolesForUserId(identityGuid);
var claims = new List<Claim>();
foreach (string role in roles)
{
claims.Add(new Claim(ClaimTypes.Role, role));
}
ticketReceivedContext.Principal.AddIdentity(new ClaimsIdentity(claims));
return Task.CompletedTask;
};
});

This is impersonation where there is a real user and you need to identify the impersonated user after login.
You will need to complete the login first, return to the app and configure the principal. Then render a UI and receive the selected choice.
You then need your UI to call the back end and tell it to update claims in the auth cookie. Not sure if you'll get this to work though - the impersonated user may need separate storage - such as a second cookie.
This highlights that it can be useful to separate the token / credential the UI receives from the claims the back end works with.
I use the below design a lot for REST APIs that serve UIs directly - though it may be overkill for your solution:
https://authguidance.com/2017/10/03/api-tokens-claims/

I think what I want to do is simply not possible without either figuring out a way to do it inside PingOne or writing my own IdentityServer and taking care of the extra steps there.
I decided to instead write a custom middleware that fires after the Authentication middleware, as described in this SO question: In asp.net core, why is await context.ChallengeAsync() not working as expected?

Forgot Password in ADB2C - (AADB2C90118), How to run a specific user flow?

Problem
I am trying to handle the 'Reset password' user-flow in my application. Upon clicking the 'Forgot Password' link, the OnRemoteFailure OpenId event is successfully triggered, successfully redirecting to the specified url 'Home/ResetPassword', but instead or redirecting to the ADB2C reset password screen, it's redirecting back to the sign-in/sign-up page.
Background
The sign-up/sign-in policy works successfully but as per Microsoft docs: https://learn.microsoft.com/en-us/azure/active-directory-b2c/active-directory-b2c-reference-policies:
" A sign-up or sign-in user flow with local accounts includes a Forgot password? link on the first page of the experience. Clicking this link doesn't automatically trigger a password reset user flow.
Instead, the error code AADB2C90118 is returned to your application. Your application needs to handle this error code by running a specific user flow that resets the password. To see an example, take a look at a simple ASP.NET sample that demonstrates the linking of user flows. "
Active Directory B2C Settings
UserFlows
Code
OpenIdEvent
protected virtual Task OnRemoteFailure(RemoteFailureContext context)
{
context.HandleResponse();
// Handle the error code that Azure AD B2C throws when trying to reset a password from the login page
// because password reset is not supported by a "sign-up or sign-in policy"
if (context.Failure is OpenIdConnectProtocolException && context.Failure.Message.Contains("AADB2C90118"))
{
// If the user clicked the reset password link, redirect to the reset password route
context.Response.Redirect("/Home/ResetPassword");
}
else if (context.Failure is OpenIdConnectProtocolException && context.Failure.Message.Contains("access_denied"))
{
context.Response.Redirect("/");
}
else
{
context.Response.Redirect("/Home/Error?message=" + WebUtility.UrlEncode(context.Failure.Message));
}
return Task.FromResult(0);
}
HomeController
public IActionResult ResetPassword()
{
var redirectUrl = Url.Action(nameof(HomeController.Index), "Home");
var properties = new AuthenticationProperties { RedirectUri = redirectUrl };
properties.Items[AzureADB2COptionsExtended.PolicyAuthenticationProperty] = _adb2cOptions.ResetPasswordPolicyId;
return Challenge(properties, AzureADB2CDefaults.AuthenticationScheme);
}
A lot of examples I found use OWIN... There is very limited documentation on ASP.Net Core 2.2 w/ ADB2C.

The Sign-up-sign-in policy now has built-in support for password resets without a second "password-reset" user flow. It is quite confusing with all the documentation and samples out there but this is the latest docs and it works for us!
https://learn.microsoft.com/en-us/azure/active-directory-b2c/force-password-reset?pivots=b2c-user-flow

Normally, the ResetPassword flow you configured in your appsettings.json is called automatically when using the Microsoft.Identity.Web package. In your case B2C_1_SSPR. That means you must define a custom user flow with this Id.
(I guess SSPR = self-service password reset)
The only thing you need in this default case is call the following in your Startup:
services.AddMicrosoftIdentityWebAppAuthentication(Configuration, "ActiveDirectoryB2C");
This works like a charm.
However, you decided to deal with all this stuff by yourself and not to use the Microsft.Identity.Web library for all processing.
In this case you are able to handle Password-reset by yourself.
But let's have a look at the Microsft.Identity.Web. They integrated an AccountController that handles the processing of the B2C custom flows (in this case the ResetPassword action).
The exception handling for AADB2C90118 can be found in the source code of the Identity package:
if (isOidcProtocolException && message.Contains(ErrorCodes.B2CForgottenPassword))
{
// If the user clicked the reset password link, redirect to the reset password route
context.Response.Redirect($"{context.Request.PathBase}/MicrosoftIdentity/Account/ResetPassword/{SchemeName}");
}

Answer that was posted in the question:
For anyone else having the same or similar issue, make sure to keep an eye out on the OpenIdConnectEvents. We have been experimenting with ADB2C/OpenID and had test code. This code was obviously invalid.
protected virtual Task OnRedirectToIdentityProvider(RedirectContext context)
{
string policy = "";
context.Properties.Items.TryGetValue(AzureADB2COptionsExtended.PolicyAuthenticationProperty, out policy);
if (!string.IsNullOrEmpty(policy) && !policy.ToLower().Equals(_adb2cOptions.DefaultPolicy.ToLower()))
{
context.ProtocolMessage.Scope = OpenIdConnectScope.OpenId;
context.ProtocolMessage.ResponseType = OpenIdConnectResponseType.IdToken;
context.ProtocolMessage.IssuerAddress = context.ProtocolMessage.IssuerAddress.ToLower().Replace(_adb2cOptions.DefaultPolicy.ToLower(), policy.ToLower());
}
return Task.FromResult(0);
}

See the latest "Self-Service Password Reset" policy (custom or non-custom) from Microsoft docs.
From the doc:
"The new password reset experience is now part of the sign-up or sign-in policy. When the user selects the Forgot your password? link, they are immediately sent to the Forgot Password experience. Your application no longer needs to handle the AADB2C90118 error code, and you don't need a separate policy for password reset."

Authentication against local AD in the Angular application

I've been developing an Angular app with .NET Core backend (services). The task is to enable an integrated authentication, i.e. make it work with the local user seamlessly, so I login to my (connected to a local AD) machine once and the web application lets me in without the necessity to login a second time. We've been working with Identity Server 4 and intended to implement this scenario using it.
There is a little documentation on the official website concerning the Windows Authentication (e.g. against Active directory): http://docs.identityserver.io/en/latest/topics/windows.html but it doesn't explain much. As per my info, to make this scenario work the browser utilizes either Kerberos or NTLM. Neither of them is mentioned in the IS4 docs. I'm lacking the understanding of how the local credentials are getting picked up and how IS4 'knows' the user belongs to AD? How I can make sure only the users from a specific domain have access to my app?
I found some working stuff here https://github.com/damienbod/AspNetCoreWindowsAuth but questions remain the same. Even though I was able to get to the app with my local account I don't understand the flow.
I expect the user utilizing the app in the local network to log-in to the app without entering the login/password (once he's already logged in to the Windows). Is this something achievable?

Identity Server is intended to serve as an Identity Provider, if you need to talk with your AD you should see the Federation Gateway architecture they propose using the IAuthenticationSchemeProvider. Where Identity Server acts as an endpoint and talks with your AD.
This is the link:
http://docs.identityserver.io/en/latest/topics/federation_gateway.html
You have the control to programmatically reach your AD and pass the correct credentials to get the authentication. That step should be done in your Identity Server. After you get authenticated you should get redirected to your application again.
About your last question, the answer is yes, if you have your website hosted on an intranet and you have the access to your AD, you don't need to capture your credentials as user input, you can programmatically reach the AD as I said.
Bellow is the code I use to connect with my active directory
On the ExternalController class, you get when you use IdentityServer, you have this:(I don't remember at the top of my head how much I changed from the original code, but you should get the idea)
/// <summary>
/// initiate roundtrip to external authentication provider
/// </summary>
[HttpGet]
public async Task<IActionResult> Challenge(string provider, string returnUrl)
{
if (string.IsNullOrEmpty(returnUrl)) returnUrl = "~/";
// validate returnUrl - either it is a valid OIDC URL or back to a local page
if (Url.IsLocalUrl(returnUrl) == false && _interaction.IsValidReturnUrl(returnUrl) == false)
{
// user might have clicked on a malicious link - should be logged
throw new Exception("invalid return URL");
}
if (AccountOptions.WindowsAuthenticationSchemeName == provider)
{
// windows authentication needs special handling
return await ProcessWindowsLoginAsync(returnUrl);
}
else
{
// start challenge and roundtrip the return URL and scheme
var props = new AuthenticationProperties
{
RedirectUri = Url.Action(nameof(Callback)),
Items =
{
{ "returnUrl", returnUrl },
{ "scheme", provider },
}
};
return Challenge(props, provider);
}
}
private async Task<IActionResult> ProcessWindowsLoginAsync(string returnUrl)
{
// see if windows auth has already been requested and succeeded
var result = await HttpContext.AuthenticateAsync(AccountOptions.WindowsAuthenticationSchemeName);
if (result?.Principal is WindowsPrincipal wp)
{
// we will issue the external cookie and then redirect the
// user back to the external callback, in essence, testing windows
// auth the same as any other external authentication mechanism
var props = new AuthenticationProperties()
{
RedirectUri = Url.Action("Callback"),
Items =
{
{ "returnUrl", returnUrl },
{ "scheme", AccountOptions.WindowsAuthenticationSchemeName },
}
};
var id = new ClaimsIdentity(AccountOptions.WindowsAuthenticationSchemeName);
id.AddClaim(new Claim(JwtClaimTypes.Subject, wp.Identity.Name));
id.AddClaim(new Claim(JwtClaimTypes.Name, wp.Identity.Name));
// add the groups as claims -- be careful if the number of groups is too large
if (AccountOptions.IncludeWindowsGroups)
{
var wi = wp.Identity as WindowsIdentity;
var groups = wi.Groups.Translate(typeof(NTAccount));
var roles = groups.Select(x => new Claim(JwtClaimTypes.Role, x.Value));
id.AddClaims(roles);
}
await HttpContext.SignInAsync(
IdentityServer4.IdentityServerConstants.ExternalCookieAuthenticationScheme,
new ClaimsPrincipal(id),
props);
return Redirect(props.RedirectUri);
}
else
{
// trigger windows auth
// since windows auth don't support the redirect uri,
// this URL is re-triggered when we call challenge
return Challenge(AccountOptions.WindowsAuthenticationSchemeName);
}
}
If you want to use Azure AD, I would recommend you to read this article:
https://damienbod.com/2019/05/17/updating-microsoft-account-logins-in-asp-net-core-with-openid-connect-and-azure-active-directory/

Not sure if it's what you want, but I would use the Active Directory Federation Services to configure an OAuth2 endpoint and obtain the user token in the .Net Core Web App.
Isn't NTLM authentication support limited on non Microsoft browsers?
OAuth2 have the advantage of using only standard technologies.

One way to do it is to have 2 instances of the app deployed.
The first one is configured to use Windows Authentication and the other one uses IS4.
ex:
yoursite.internal.com
yoursite.com
Your local DNS should redirect traffic internally from yoursite.com to yoursite.internal.com
yoursite.internal.com will be the one configured to use AD authentication. You should have a flag in your appsettings.json to indicate if this instance is a AD auth or IS4 auth.
The downside of this solution is that you have to deploy 2 instances