.NET Guidebook

Web Development

.NET CORS

Handling CORS

.NET CORS enables cross-origin requests with middleware.

Introduction to CORS

Cross-Origin Resource Sharing (CORS) is a security feature implemented by browsers to prevent malicious websites from accessing resources on a different domain without permission. In .NET applications, CORS is handled using middleware, allowing you to configure which domains can access your resources.

Setting Up CORS in .NET

To enable CORS in your .NET application, you need to configure it in the Startup.cs file. This involves specifying the allowed origins, methods, headers, and other options.

Configuring CORS in Startup.cs

First, add the CORS services to the service collection. This is done in the ConfigureServices method:

Applying CORS Middleware

Next, apply the CORS middleware in the Configure method to enable the policy:

Understanding CORS Policies

CORS policies define the rules that determine which external domains can interact with your application's resources. The example above uses a specific origin. You can also allow multiple origins, or use .AllowAnyOrigin() to permit all domains, although this should be done cautiously due to security risks.

Advanced CORS Configuration

For more advanced configurations, you can specify allowed HTTP methods, headers, and credentials. Here's an example:

Conclusion

By configuring CORS in your .NET applications, you can control access to your resources based on specific rules, enhancing both security and functionality. Properly setting CORS policies helps prevent unauthorized access while allowing legitimate use cases.

Web Development

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