Tutorial: Prepare your external tenant to authorize a .NET daemon application

In this tutorial series, you'll learn how to build a .NET daemon app that calls your own custom protected web API using Microsoft Entra External ID. You'll register an app in Microsoft Entra ID and authenticate your app with your external tenant. Finally, you'll run the app and test the sign-in and sign-out experiences.

Prerequisites

• A Microsoft Entra ID for external tenant. If you don't have one, create a trial tenant or a tenant with a subscription before you begin.
• This Azure account must have permissions to manage applications. Any of the following Microsoft Entra roles include the required permissions:
  • Application Administrator
  • Application Developer
  • Cloud Application Administrator

Register a web API application

1. Sign in to the Microsoft Entra admin center as at least an Application Developer.

2. If you have access to multiple tenants, use the Settings icon in the top menu to switch to your external tenant from the Directories + subscriptions menu.

3. Browse to Identity > Applications > App registrations.

4. Select + New registration.

5. In the Register an application page that appears, enter your application's registration information:

   1. In the Name section, enter a meaningful application name that will be displayed to users of the app, for example ciam-ToDoList-api.

   2. Under Supported account types, select Accounts in this organizational directory only.

6. Select Register to create the application.

7. The application's Overview pane is displayed when registration is complete. Record the Directory (tenant) ID and the Application (client) ID to be used in your application source code.

Configure app roles

An API needs to publish a minimum of one app role for applications, also called Application Permission, for the client apps to obtain an access token as themselves. Application permissions are the type of permissions that APIs should publish when they want to enable client applications to successfully authenticate as themselves and not need to sign-in users. To publish an application permission, follow these steps:

1. From the App registrations page, select the application that you created (such as ciam-ToDoList-api) to open its Overview page.

2. Under Manage, select App roles.

3. Select Create app role, then enter the following values, then select Apply to save your changes:

   Property	Value
   Display name	ToDoList.Read.All
   Allowed member types	Applications
   Value	ToDoList.Read.All
   Description	Allow the app to read every user's ToDo list using the 'TodoListApi'

4. Select Create app role again, then enter the following values for the second app role, then select Apply to save your changes:

   Property	Value
   Display name	ToDoList.ReadWrite.All
   Allowed member types	Applications
   Value	ToDoList.ReadWrite.All
   Description	Allow the app to read and write every user's ToDo list using the 'ToDoListApi'

Configure idtyp token claim

You can idtyp optional claim to help the web API to determine if a token is an app token or an app + user token. Although you can use a combination of scp and roles claims for the same purpose, using the idtyp claim is the easiest way to tell an app token and an app + user token apart. For example, the value of this claim is app when the token is an app-only token.

Register the daemon app

To enable your application to sign in users with Microsoft Entra, Microsoft Entra External ID must be made aware of the application you create. The app registration establishes a trust relationship between the app and Microsoft Entra. When you register an application, External ID generates a unique identifier known as an Application (client) ID, a value used to identify your app when creating authentication requests.

The following steps show you how to register your app in the Microsoft Entra admin center:

1. Sign in to the Microsoft Entra admin center as at least an Application Developer.

2. If you have access to multiple tenants, use the Settings icon in the top menu to switch to your external tenant from the Directories + subscriptions menu.

3. Browse to Identity >Applications > App registrations.

4. Select + New registration.

5. In the Register an application page that appears;

   1. Enter a meaningful application Name that is displayed to users of the app, for example ciam-client-app.
   2. Under Supported account types, select Accounts in this organizational directory only.

6. Select Register.

7. The application's Overview pane displays upon successful registration. Record the Application (client) ID to be used in your application source code.

Create a client secret

Create a client secret for the registered application. The application uses the client secret to prove its identity when it requests for tokens.

1. From the App registrations page, select the application that you created (such as ciam-client-app) to open its Overview page.
2. Under Manage, select Certificates & secrets.
3. Select New client secret.
4. In the Description box, enter a description for the client secret (for example, ciam app client secret).
5. Under Expires, select a duration for which the secret is valid (per your organizations security rules), and then select Add.
6. Record the secret's Value. You'll use this value for configuration in a later step. The secret value won't be displayed again, and isn't retrievable by any means, after you navigate away from the Certificates and secrets. Make sure you record it.

Grant API permissions to the daemon app

1. From the App registrations page, select the application that you created, such as ciam-client-app.

2. Under Manage, select API permissions.

3. Under Configured permissions, select Add a permission.

4. Select the APIs my organization uses tab.

5. In the list of APIs, select the API such as ciam-ToDoList-api.

6. Select Application permissions option. We select this option as the app signs in as itself, but not on behalf of a user.

7. From the permissions list, select TodoList.Read.All, ToDoList.ReadWrite.All (use the search box if necessary).

8. Select the Add permissions button.

9. At this point, you've assigned the permissions correctly. However, since the daemon app doesn't allow users to interact with it, the users themselves can't consent to these permissions. To address this problem, you as the admin must consent to these permissions on behalf of all the users in the tenant:

   1. Select Grant admin consent for <your tenant name>, then select Yes.
   2. Select Refresh, then verify that Granted for <your tenant name> appears under Status for both permissions.

Record your app registration details

The next step after this tutorial is to build a daemon app that calls your web API. Ensure you have the following details:

• The Application (client) ID of the client daemon app that you registered.
• The Directory (tenant) subdomain where you registered your daemon app. If you don't have your tenant name, learn how to read your tenant details.
• The application secret value for the daemon app you created.
• The Application (client) ID of the web API app you registered.

Next step