Introduction
When working with a Blazor (Server-side) application that utilizes Windows Authentication, you may encounter a situation where the authentication works seamlessly when running the application using IIS but fails when using Kestrel. Additionally, you may observe that the authentication does not function properly in Chrome, sometimes works in Edge, and consistently works in Internet Explorer (IE). In this blog post, we will explore the possible causes and solutions for this issue, specifically related to the usage of Microsoft.AspNetCore.Authentication.Negotiate.
The Problem: Inconsistency in Authentication
After setting up a Blazor application with Windows Authentication, you notice that the “Hello Domain\User!” message is displayed correctly when running the application with IIS. However, when using Kestrel, the message does not appear. Additionally, you experience inconsistent behavior across different browsers, with Chrome failing to authenticate properly, Edge sometimes working, and IE consistently displaying the authentication message.
Possible Solution: ValidateAuthentication Middleware
To resolve the authentication issue, we can utilize a custom middleware called ValidateAuthentication. This middleware will check if the user is authenticated and either allow the request to proceed or challenge the authentication. Follow the steps below to implement this solution:
- Add the following code in the
ConfigureServices
method in theStartup.cs
file:
csharpCopy code
services.AddSingleton<ValidateAuthentication>();
- Add the following code in the
Configure
method in theStartup.cs
file, before theapp.UseEndpoints(...)
line:
csharpCopy code
app.UseMiddleware<ValidateAuthentication>();
- Implement the
ValidateAuthentication
middleware as shown below:
code
using Microsoft.AspNetCore.Http;
using System.Threading.Tasks;
public class ValidateAuthentication : IMiddleware
{
public async Task InvokeAsync(HttpContext context, RequestDelegate next)
{
if (context.User.Identity.IsAuthenticated)
{
await next(context);
}
else
{
await context.ChallengeAsync();
}
}
}
- Save the changes and run the application again using Kestrel.
By adding the ValidateAuthentication
middleware, we ensure that the user is authenticated before allowing the request to proceed. If the user is not authenticated, the middleware will challenge the authentication and prompt the user to provide valid credentials.
Additional Considerations
It’s worth noting that the inconsistency in authentication across different browsers may be due to the browser settings related to automatic logon with the current username and password. Make sure to verify and modify the user authentication mode in the browser settings to prompt for username and password, rather than using automatic logon.
Conclusion
In this blog post, we addressed the issues related to Windows Authentication not working as expected on Kestrel with the Microsoft.AspNetCore.Authentication.Negotiate package. By implementing the ValidateAuthentication
middleware and reviewing browser settings, you can troubleshoot and resolve authentication issues. We hope these steps have been helpful in getting your Windows Authentication up and running smoothly in your Blazor application.
If you have any further questions or need additional assistance, feel free to leave a comment below. Happy coding and enjoy the seamless authentication experience with Windows Authentication in your Blazor application!