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2024.07.06 - [Microsoft 365/Entra ID] - Microsoft Entra ID. Set up tenant restrictions v2 by GPO (English)

Continuing from the previous post, this time we will proceed with setting tenant restrictions using GSA.

Youtube (English)

https://youtu.be/PIfHu4yPjN4

Step 1 is the same process as in the previous post.

The client PC has already been joined to Entra ID in advance.

Step 1: Configure default tenant restrictions v2

Entra Admin Center > Cross-tenant access settings > cross-tenant access settings > Default settings

Edit tenant restrictions defaults

Create Policy

The Policy ID is generated as shown below. Make sure to copy each value and keep them.

To set up a blocking policy for external accounts, configure it as shown below (default settings).

To block all external apps, configure the settings as shown below.

Step 2: Configure GSA

Click on Global Secure Access -> Activate to enable it.

Connect -> Traffic forwarding -> Activate each profile.

Proceed with assigning users and groups.

Assign to all users -> Yes

Secure -> Security profiles -> Create profile

Enter the profile name.

Link policy -> Existing policy

Link the default policy -> Proceed with the profile creation process.

Baseline profile

Change to Enabled status.

Step 3: Install GSA Client

Connect -> Client download

Download client (When deploying to actual users, Intune can be utilized.)

Proceed with the installation process of the GSA Client.

Sign in

Verify the connection status as shown below.

When logging in to a different tenant in Chrome, you can confirm that it is blocked as shown below.

The downside of the preview version is that the client has a Pause button.

Once officially released, it is expected to be built into the Windows service, similar to MDE.

I will discuss Tenant restriction settings.

The primary purpose of Conditional Access is to prevent company accounts from being accessed on personal devices. However, Conditional Access cannot prevent other company accounts from being accessed on company devices.

Of course, if a company device can access Naver Mail and Google Drive, it means the company is not very concerned about data leakage, and you may disregard this post.

To use M365, you need to open MS-related URLs such as office.com. Tenant Restriction is a concept used to prevent access with other company or personal accounts (such as outlook.com) during this time.

Youtube (English)

https://youtu.be/z-sVlZoz3y8

Technical article

Configure tenant restrictions - Microsoft Entra ID - Microsoft Entra External ID | Microsoft Learn

There are three main methods:

1. GSA
2. Company Proxy Equipment
3. GPO

The method using GSA requires a prior understanding of GSA.

I will cover that part separately later.

In this post, I will apply tenant restrictions using the third option, GPO.

Step 1: Configure default tenant restrictions v2

Entra Admin Center > Cross-tenant access settings > cross-tenant access settings > Default settings

Edit tenant restrictions defaults

Create Policy

The Policy ID is generated as shown below. Make sure to copy each value and keep them.

To set up a blocking policy for external accounts, configure it as shown below (default settings).

To block all external apps, configure the settings as shown below.

Step 2: Enable tenant restrictions on Windows managed devices (preview)

In the technical documentation, there are guidelines as shown below.

Tenant restrictions V2 on Windows is a partial solution that protects the authentication and data planes for some scenarios. It works on managed Windows devices and does not protect .NET stack, Chrome, or Firefox. The Windows solution provides a temporary solution until general availability of Universal tenant restrictions in Microsoft Entra Global Secure Access (preview).

-> Although the content is difficult to understand, it can be interpreted as indicating that the feature will be provided in a different way in the future. Currently, it is in the preview stage.

Download the ADMX files for the latest Windows GPO policies.

Download Administrative Templates (.admx) for Windows 11 2023 Update (23H2) from Official Microsoft Download Center

Once installed, the policy files will be saved to the following location.

Depending on the method of policy deployment in AD, copy the PolicyDefinitions folder to the appropriate location with only the necessary languages. (This part of the policy is related to AD, so we will not cover it here.)

Run gpmc.msc on the Domain Controller (DC).

Create a policy in the Organizational Unit (OU) that you will use for testing. Right-click and select "Edit".

Computer Configuration > Administrative Templates > Windows Components > Tenant Restrictions

Configure the settings as shown below.

Attempt to log in with a personal account on Edge.

Verify that access is blocked as shown below.

You can also see that access is blocked when attempting to log in with another tenant account.

There has always been a need to synchronize address books (GAL) between companies in scenarios such as M&A, affiliated companies, or group companies, where using a single tenant is not possible. Traditionally, this was achieved by setting up servers like Microsoft Identity Manager (MIM) on an On-Premise Exchange Server, creating objects between ADs to synchronize address books. Alternatively, it could be implemented through HR integration solutions.

However, adopting MIM or HR integration solutions can be prohibitively expensive and requires specialized knowledge for management, making it very burdensome.

Recently, it has become possible to synchronize address books with Cross-tenant Synchronization. Specifically, this functionality automates the invitation of Guests.

https://youtu.be/-HtT_uuDul0

The following content was written based on the technical documentation below.

Configure cross-tenant synchronization - Microsoft Entra ID | Microsoft Learn

Settings are configured separately for the Source Tenant and the Target Tenant.

Step 1: Plan your provisioning deployment

First, collect the information for the Source Tenant and the Target Tenant.

Source Tenant

Domain: Contoso.kr

Tenant ID: a0c898ca-2445-4e74-ab4b-afd7916549a6

Target Tenant

Domain: fabrikam.kr

Tenant ID: afab079d-1f08-4de3-881e-435e497f923f

Step 2: Enable user synchronization in the target tenant

Entra Admin Center > External Identities > Organizational settings > Add organization

Enter the Source Tenant ID information. > Add

Inbound access > Inherited from default

Allow users sync into this tenant > Check

Step 3: Automatically redeem invitations in the target tenant

Trust settings > Automatically redeem invitations with the tenant [Tenant Name] > Check > Save

Step 4: Automatically redeem invitations in the source tenant

Entra Admin Center > External Identities > Cross-tenant access settings

Add organization

Enter Target Tenant ID > Add

Outbound access > Inherited from default

Trust settings > Automatically redeem invitations with the tenant Fabrikam > Check > Save

Step 5: Create a configuration in the source tenant

Cross-tenant synchronization

Configurations > New configuration

Specify the configuration name. > Create

Step 6: Test the connection to the target tenant

Get started

Provisioning Mode: Automatic > Admin Credentials > Tenant Id: Target Tenant ID > Test Connection > Save

Step 7: Define who is in scope for provisioning (Source Tenant)

Provisioning > Settings > Confirm Scope  > Sync only assinged users and groups:

This means specifying only certain users or groups to synchronize.

Users and groups  -> Add user/group

None Selected

Specify the target. > Select > Assign

Step 9: Review attribute mappings

If, for various reasons, you do not want to synchronize specific attributes, proceed as follows.

Provisioning > Mappings > Provision Microsoft Entra ID Users

You can remove some items except for the required fields.

Step 10: Start the provisioning job

Start provisioning

Target Tenant > Entra admin center > Users > All Users

You can verify that they are added as guests as shown below.

You can also verify this in the Exchange Admin Center as shown below.

You can also verify this in the address book as shown below.

Tenant-to-tenant synchronization settings are configured as follows: In the Source Tenant, set up the Outbound settings, and in the Target Tenant, set up the Inbound settings. This synchronization process results in Guest accounts. Since Guest accounts have Mail User attributes, they can be verified in the address book.