Restrict device access with Microsoft Intune

Microsoft Intune collects a series of signals from the MDM profile installed on devices and these signals can be used to determine the security posture of a device. Tailscale can fetch these signals from Intune and use them as device posture attributes in access rules, which can allow organizations to grant access to sensitive resources only to devices that have a high enough level of trust.

This can be achieved using Tailscale's device posture management features:

• Device Identity Collection, which collects identifiers (for example, serial numbers), used to match devices in Tailscale to devices in Intune.
• Intune posture integration, which synchronizes signals from Intune to device posture attributes in Tailscale.
• Posture conditions in access rules, which lets you configure access restrictions based on device attributes.

This guide explains how to enable Device Identity collection for your Tailscale network (tailnet) and configure Microsoft Intune posture integration.

What is Intune posture integration?

The Intune integration syncs data between Intune and Tailscale on a recurring schedule. During each sync, Tailscale performs the following actions:

1. Fetches a list of hosts and their reported data from your Intune account.
2. Matches Intune devices to devices in your tailnet based on serial numbers.
3. Writes the Intune data to device posture attributes on each matched device.

The integration writes the following device posture attributes to matched devices:

Prerequisites

• Device Identity Collection is enabled, and devices in your tailnet are reporting identifiers
• An Azure Application credential to connect to Microsoft Intune

Create Azure Application credential to connect Intune

To authenticate your Intune account with Tailscale, you'll need to create a set of Azure Application credentials. The Microsoft Intune integration uses these credentials to connect to the Microsoft Graph API and fetch a list of devices and their data from Intune.

To create an Azure Application and credentials:

1. In Azure Portal, in the Azure Services menu, select App registrations.

2. Select New registration.

3. Enter a name for the application, for example, Tailscale and select Register. Take note of the Application (Client) ID and Directory (Tenant) ID for later.

4. Under Essentials, select Add a certificate or secret.

5. Select New client secret.

6. Enter a description for the secret, select an expiration period, and select Add. Take note of the Value for later.

7. Under API permissions, select Add a permission.

8. Select Microsoft Graph.

9. Select Application permissions.

10. Search for and select DeviceManagementManagedDevices.Read.All and select Add permissions.

11. Select Grant admin consent for your-organization and select Yes.

Configure Intune posture integration

To configure Tailscale to fetch data about devices from Intune:

1. Open the Device management page of the Tailscale admin console.

2. Under the Device Posture Integrations section, locate the Intune integration, then select Connect.

3. Select your Microsoft Region, the region where your Intune account is located.

4. Enter your Application (Client) ID, Directory (Tenant) ID and Client Secret.

   

5. Select Connect to Intune.

Review the integration status

After you set up the Intune integration, check to ensure the integration has run successfully. You can do so by visiting the Device Posture Integrations section of the Device management page. This page shows the configured integrations and their statuses under the Integrations section. For the Intune integration, it should have the time of the most recent sync, the number of synced devices, and any errors that occurred while synchronizing.

Check node attributes

After you configure Intune integration, you can confirm that Tailscale is writing the new attribute for your Intune devices on the Machines page of the admin console.

1. Open the Machines page of the Tailscale admin console.
2. Select a device to inspect.
3. The attributes for the device are in the Machine Details section. This should include the set of intune: attributes listed previously.

You can also check device attributes using the Tailscale API.

Adjust Tailscale access rules

After you configure Intune posture integration, and your devices have device posture attributes that reflect their signals as reported by Intune, you can use those device posture attributes as part of your posture rules.

For example, to only permit access to tag:production from devices that Intune reports as compliant and supervised by Intune, you can create a new posture and use it as part of a corresponding access rule:

"postures": {
  "posture:trusted": [
    "intune:complianceState == 'compliant'",
    "intune:isSupervised == true",
  ],
},
"grants": [
  {
    "src": ["autogroup:member"],
    "dst": ["tag:production"],
    "ip": ["*"],
    "srcPosture": ["posture:trusted"]
  }
]

Schedule

For each configured integration, Tailscale will aim to sync device posture attributes every 15 minutes, with a few exceptions:

• Adding a new integration, or changing configuration of an existing one, will trigger an out-of-schedule sync.
• If an integration fails due to authentication error (usually caused by invalid credentials), it will be paused for up to 24 hours.

Limitations

We have observed that Intune does not report serial numbers for some machines running Linux. Without serial number details, Tailscale will not be able to populate device posture attributes for such machines.

Audit log events

The following audit log events are added for device posture.