Скачать или смотреть How to Require Authentication in ASP.NET Core 5 Blazor Server Mode with Redirect to Login

Learn how to configure authentication in ASP.NET Core 5 for Blazor Server applications to redirect unauthenticated users to a login page efficiently.
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Understanding Authentication in ASP.NET Core 5 for Blazor Server

When developing applications, security is always a top priority, particularly when it comes to managing user access. If you are creating a Blazor Server app using ASP.NET Core 5, you may find yourself needing to require user authentication. In this post, we'll walk through how to set up authentication correctly and ensure that users are redirected to a login page when they attempt to access restricted resources without being authenticated.

The Authentication Challenge

You might be facing challenges with the default authorization policy when using the BlazorHub endpoint. What happens if a user attempts to access the application without being authenticated? Ideally, you would like them to be prompted for login, but finding the correct configuration can be tricky.

In this guide, we will share the proper setup to ensure that your application redirects users to the login page when they are not authenticated.

Setting Up Authentication in Blazor Server

Here are the steps to configure authentication properly in your ASP.NET Core 5 Blazor application:

Step 1: Modify the Startup Class

You must ensure that authentication services are registered and used in your application. Below is the modified Startup class.

Configuring Services

In the ConfigureServices method, you will add necessary services for Razor Pages and Server-Side Blazor along with configuring authentication:

[[See Video to Reveal this Text or Code Snippet]]

Configuring Middleware

In the Configure method, you will need to set up the middleware to utilize authentication and authorization features:

[[See Video to Reveal this Text or Code Snippet]]

Step 2: Adding Authentication Middleware

It’s critical to ensure that both UseAuthentication and UseAuthorization are called before setting up your endpoints. This ensures that any request routed through the application goes through the authentication process first, which is key to redirecting unauthenticated users to the login page.

Step 3: Defining the Login and Logout Paths

Make sure you have defined the paths for both login and logout in your cookie authentication options. This allows the application to know where to redirect users when they attempt to access a secured page without being authenticated.

Summary

By following the above configuration setup, your Blazor Server app will require authentication for both Razor Pages and BlazorHub. Users who are unauthenticated will automatically be redirected to the login page you've specified. This provides a smooth and secure user experience, ensuring that sensitive parts of your application stay protected.

Key Takeaways:

Configure the Authentication Services: Ensure all necessary authentication services are added.

Use Middleware: Properly order your middleware to handle authentication.

Secure Pages: Ensure both Razor and Blazor pages require authentication.

By implementing these steps in your project, you will create a reliable authentication mechanism that enhances the security of your Blazor Server application.

If you have any questions or need further clarification, feel free to reach out or leave a comment below!