Ensuring Safe External Access to Your API with IdentityServer4

Описание: Discover how to securely provide `external users` access to your API using IdentityServer4, including client registration and database management practices.
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This video is based on the question https://stackoverflow.com/q/67772310/ asked by the user 'leo' ( https://stackoverflow.com/u/4634961/ ) and on the answer https://stackoverflow.com/a/67772993/ provided by the user 'Tore Nestenius' ( https://stackoverflow.com/u/68490/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Opening Access to Your API for External Users with IdentityServer4

In today's interconnected world, sharing resources and services has become a necessity for many organizations. One common challenge developers face is how to extend API access to users outside their organization while ensuring the security of sensitive information. This post explores how to give external users access to an already protected API using IdentityServer4, which serves as an identity provider in securing APIs.

Understanding the Problem

You have an API, named APISample, that is protected using IdentityServer4. Your organization uses this API internally, and now you want to grant access to external users. These users wish to interact with your API through their applications, which may include Angular and .NET Windows applications.

Key components you need to consider before proceeding:

API Resource: APISample

API Scopes: api.read, api.write

The main question is: How do you safely allow these external users to access your existing API?

The Solution: Registering Clients and Managing Access

To facilitate external access while maintaining security, you’ll need a structured approach. Here’s how you can achieve that.

1. Client Registration

Begin by enabling external users to register their applications with IdentityServer4. This can be done in two ways:

Self-service Registration: Allow external users to register through a portal you create. This can be implemented as a web application where potential clients can provide their application details and request access to specific scopes (api.read and api.write).

Manual Registration: If you prefer tighter control, you can register the clients yourself and provide them with the necessary credentials.

2. Define Scopes and Claims

Ensure that the registered clients agree on the specific scopes and claims they will require for access. In your case, they will likely need:

Scopes for Reading Data: api.read

Scopes for Writing Data: api.write

This agreement is crucial to ensure that external clients can only access the resources they are permitted to use.

3. Implementing a Database-Driven Approach

You can store the client application details in a database. Here are several steps to consider:

Database Structure: Create a table that stores the registered clients, their credentials, and the scopes they have agreed upon.

Manage Access Tokens: Use a token management strategy to issue and validate access tokens for external users. This typically includes using JWT (JSON Web Tokens) to securely transmit information between the client and your API.

Secure Your API Endpoints: Ensure that all endpoints in your API validate incoming requests based on the scopes present in the access token.

4. Portal Development

The portal where external users will register their applications is crucial for enabling scalable management of API consumers. Here’s what to keep in mind while developing this portal:

Introduce clear user interfaces for the registration process.

Integrate validation mechanisms to ensure only authorized applications are granted access.

Provide thorough documentation for external users to help them understand how to authenticate and utilize your API efficiently.

Conclusion

Granting external users access to your IdentityServer4-protected API requires careful planning and implementation. By allowing clients to register themselves or manually registering clients while ensuring a structured database-driven approach, you can maintain the security of your API resources.

Implement the steps outlined in this blog to facilitate external access to your API while still adhering to best practices in API security. By doing so, you allow your organiza