Always On VPN with Azure Gateway

Always On VPN with Azure GatewayRecently I wrote about VPN server deployment options for Windows 10 Always On VPN in Azure. In that post I indicated the native Azure VPN gateway could be used to support Always On VPN connections using Internet Key Exchange version 2 (IKEv2) and Secure Socket Tunneling Protocol (SSTP). In this post I’ll outline the requirements and configuration steps for implementing this solution.

Requirements

To support Always On VPN, point-to-site VPN connections must be enabled on the Azure VPN gateway. Not all Azure VPN gateways are alike, and point-to-site connections are not supported in all scenarios. For Always On VPN, the Azure VPN gateway must meet the following requirements.

VPN SKU

The Azure VPN gateway SKU must be VpnGw1, VpnGw2, VpnGw3, VpnGw1AZ, VpnGw2AZ, or VpnGw3AZ. The Basic SKU is not supported.

VPN Type

The VPN type must be route-based. Policy-based VPN gateways are not supported for point-to-site VPN connections.

Limitations

Using the Azure VPN gateway for Always On VPN may not be ideal in all scenarios. The following limitations should be considered thoroughly before choosing the Azure VPN gateway for Always On VPN.

Device Tunnel

RADIUS/EAP authentication for user tunnel connections is not supported if the Azure VPN gateway is configured to support device tunnel with machine certificate authentication.

Maximum Connections

A maximum of 250, 500, and 1000 concurrent IKEv2 connections are supported when using the VpnGw1/AZ, VpnGw2/AZ, and VpnGw3/AZ SKUs, respectively (x2 for active/active gateway deployments). In addition, a maximum of 128 concurrent SSTP connections are supported for all VPN gateway SKUs (x2 for active/active gateway deployments).

Always On VPN with Azure Gateway

Reference: https://docs.microsoft.com/en-us/azure/vpn-gateway/vpn-gateway-about-vpngateways#gwsku

RADIUS Requirements

To support Always On VPN connections, the Azure VPN gateway must be configured to authenticate to a RADIUS server. The RADIUS server must be reachable from the VPN gateway subnet. The RADIUS server can be hosted in Azure or on-premises. Before proceeding, ensure that any network routes, firewall rules, and site-to-site VPN tunnel configuration is in place to allow this communication.

RADIUS Configuration

Guidance for configuring Windows Server NPS for Always On VPN can be found here. The only difference when configuring NPS for use with Azure VPN gateway is the RADIUS client configuration.

Open the NPS management console (nps.msc) and follow the steps below to configure Windows Server NPS to support Always On VPN client connections from the Azure VPN gateway.

1. Expand RADIUS Clients and Servers.
2. Right-click RADIUS Clients and choose New.
3. Enter a descriptive name in the Friendly name field.
4. Enter the Azure VPN gateway subnet using CIDR notation in the Address (IP or DNS) field. The gateway subnet can be found by viewing the properties of the Azure VPN gateway in the Azure portal.
5. Enter the shared secret to be used for RADIUS communication in the Shared secret field.

Always On VPN with Azure Gateway

Azure VPN Gateway Configuration

To begin, provision a Virtual Network Gateway in Azure that meets the requirements outlined above. Guidance for implementing an Azure VPN gateway can be found here. Once complete, follow the steps below to enable support for Always On VPN client connections.

Enable Point-to-Site

Perform the following steps to enable point-to-site VPN connectivity.

1. In the navigation pane of the Azure VPN gateway settings click Point-to-site configuration.
2. Click Configure Now and specify an IPv4 address pool to be assigned to VPN clients. This IP address pool must be unique in the organization and must not overlap with any IP address ranges defined in the Azure virtual network.
3. From the Tunnel type drop-down list select IKEv2 and SSTP (SSL).
4. In the RADIUS authentication field enter the IPv4 address of the RADIUS server. At the time of this writing only a single IPv4 address is supported. If RADIUS redundancy is required, consider creating a load balanced NPS cluster.
5. In the Server secret field enter the RADIUS shared secret.
6. Click Save to save the configuration.

Always On VPN with Azure Gateway

VPN Client Configuration

Perform the following steps to configure a Windows 10 VPN client to connect to the Azure VPN gateway.

Download VPN Configuration

1. Click Point-to-site configuration.
2. Click Download VPN client.
3. Select EAPMSCHAv2 (yes, that’s correct even if EAP-TLS will be used!)
4. Click Download.
5. Open the downloaded zip file and extract the VpnSettings.XML file from the Generic folder.
6. Copy the FQDN in the VpnServer element in VpnSettings.XML. This is the FQDN that will be used in the template VPN connection and later in ProfileXML.

Always On VPN with Azure Gateway

Create a Test VPN Connection

On a Windows 10 device create a test VPN profile using the VPN server address copied previously. Configure EAP settings to match those configured on the NPS server and test connectivity.

Create an Always On VPN Connection

Once the VPN has been validated using the test profile created previously, the VPN server and EAP configuration from the test profile can be used to create the Always On VPN profile for publishing using Intune, SCCM, or PowerShell.

IKEv2 Security Configuration

The default IKEv2 security parameters used by the Azure VPN gateway are better than Windows Server, but the administrator will notice that a weak DH key (1024 bit) is used in phase 1 negotiation.

Always On VPN with Azure Gateway

Use the following PowerShell commands to update the default IKEv2 security parameters to recommended baseline defaults, including 2048-bit keys (DH group 14) and AES-128 for improved performance.

Connect-AzAccount
Select-AzSubscription -SubscriptionName [Azure Subscription Name]

$Gateway = [Gateway Name]
$ResourceGroup = [Resource Group Name]

$IPsecPolicy = New-AzVpnClientIpsecParameter -IpsecEncryption AES128 -IpsecIntegrity SHA256 -SALifeTime 28800 -SADataSize 102400000 -IkeEncryption AES128 -IkeIntegrity SHA256 -DhGroup DHGroup14 -PfsGroup PFS14

Set-AzVpnClientIpsecParameter -VirtualNetworkGatewayName $Gateway -ResourceGroupName $ResourceGroup -VpnClientIPsecParameter $IPsecPolicy

Note: Be sure to update the cryptography settings on the test VPN connection and in ProfileXML for Always On VPN connections to match the new VPN gateway settings. Failing to do so will result in an IPsec policy mismatch error.

Additional Information

Microsoft Azure VPN Gateway Overview

About Microsoft Azure Point-to-Site VPN

Windows 10 Always On VPN IKEv2 Security Configuration

 

 

 

Always On VPN DNS Registration Update Available

Always On VPN DNS Registration Update AvailableWhen configuring Always On VPN, administrators have the option to enable DNS registration for VPN clients. When this option is set, VPN clients will register the IP address assigned to their VPN interface in the internal DNS. This allows client devices to be managed using their hostname from the internal network whenever they are connected remotely.

DNS Registration

DNS registration is enabled in one of two ways, depending on how Always On VPN client devices are managed.

Intune

When using the native Microsoft Intune UI to manage Always On VPN profiles, DNS registration can be configured by selecting Enabled next to Register IP addresses with internal DNS in the Base VPN settings section.

Always On VPN DNS Registration Update Available

ProfileXML

When using custom ProfileXML with PowerShell, SCCM, or Intune, the administrator will define the RegisterDNS element to enable DNS registration.

Always On VPN DNS Registration Update Available

Known Issues

Some users have reported unexpected behavior when DNS registration is enabled. Specifically, under some circumstances the VPN client will register the IP address of the VPN network interface along with the IP address of its public network interface (Wi-Fi, Ethernet, etc.). However, the VPN client can only be managed using the VPN interface. If the VPN client’s hostname resolves to its public IP address, manage out will fail.

This appears to happen only when Name Resolution Policy Table (NRPT) rules are defined in Intune DNS settings, or if the DomainNameInformation element is defined in ProfileXML.

Always On VPN DNS Registration Update AvailableAlways On VPN DNS Registration Update Available

Resolution

Microsoft recently released fixes for this DNS registration issue for Windows 10. The fix for this issue is included in the following updates.

Windows 10 1803 – KB4507466
Windows 10 1809 – KB4505658
Windows 10 1903 – KB4505903

Additional Configuration

After installing the update, the following registry entry must be defined on each VPN client.

HKLM\SYSTEM\CurrentControlSet\Services\Dnscache\Parameters\DisableNRPTForAdapterRegistration DWORD = 1

To enable this setting, open an elevated PowerShell window and run the following command.

New-ItemProperty -Path ‘HKLM:SYSTEM\CurrentControlSet\Services\Dnscache\Parameters\’ -Name DisableNRPTForAdapterRegistration -PropertyType DWORD -Value 1 -Force

Once complete, restart the client device for the changes to take effect. After validation testing is complete, the registry entry can be deployed to Always On VPN clients using Active Directory group policy preferences or Intune.

Additional Information

Deploying Windows 10 Always On VPN with Intune using Custom ProfileXML

Windows 10 Always On VPN Updates to Improve Connection Reliability

Windows 10 Always On VPN Device Tunnel Configuration using Microsoft Intune

Windows 10 Always On VPN Hands-On Training Classes

Deploying Always On VPN with Intune using Custom ProfileXML

Deploying Always On VPN with Intune using Custom ProfileXMLWhen deploying Windows 10 Always On VPN using Microsoft Intune, administrators have two choices for configuring VPN profiles. They can use the native Intune user interface (UI) or create and upload a custom ProfileXML. The method chosen will depend on which features and settings are required.

Microsoft Intune

Intune has an intuitive user interface (UI) that can be used to configure and deploy Always On VPN profiles to Windows 10 clients. Guidance for using the UI to deploy Windows 10 Always On VPN with Microsoft Intune can be found here. However, Intune does not expose all Always On VPN settings to the administrator, which can be problematic.

Missing from Intune

At the time of this writing, the following Always On VPN settings cannot be configured natively using the Intune UI.

To implement any of the above features or settings the administrator must create and upload a custom ProfileXML.

ProfileXML

ProfileXML is a node within the VPNv2 Configuration Service Provider (CSP). When configuring Always On VPN using the Intune UI, each setting is configured individually. By contrast, the ProfileXML node includes all Always On VPN settings in a single configuration file. It can be deployed using Intune or PowerShell. Sample ProfileXML files for both user and device tunnels can be downloaded from my GitHub repository.

ProfileXML and Intune

I’ve already documented how to deploy an Always On VPN device tunnel configuration using Intune, so this post will focus on deploying the user tunnel using ProfileXML.

Once ProfileXML has been configured, open the Intune management console and follow the steps below to deploy it using Intune.

Create Profile

1. In the navigation pane click Device Configuration.
2. Click Profiles.
3. Click Create Profile.
4. Enter a descriptive name for the new VPN profile.
5. Select Windows 10 and later from the Platform drop-down list.
6. Select Custom from the Profile type drop-down list.

Custom OMA-URI Settings

1. In the Custom OMA-URI Settings blade click Add.
2. Enter a descriptive name in the Name field (this name will appear in the Windows UI on the client).
3. Enter ./User/Vendor/MSFT/VPNv2/Always%20On%20VPN/ProfileXML in the OMA-URI field. I’ve used Always On VPN as an example here, but you can use any text you like. If it includes spaces they must be escaped using %20, as shown here. Also, don’t forget to include the leading “.“.
4. Select String (XML file) from the Data type drop-down list.
5. Click the folder next to the Select a file field and select your ProfileXML file.
6. Click Ok.

Deploying Always On VPN with Intune using Custom ProfileXML

Important Note: The File contents window must show the contents of your ProfileXML. If the contents are unreadable the XML file contains encoding that will not work. If this happens, copy the contents of your ProfileXML to another new text file and upload again.

Assign Profile

Follow the steps below to assign the Always On VPN profile to the appropriate user group.

1. Click Assignments.
2. Click Select groups to include.
3. Select the group that includes the target users.
4. Click Select.
5. Click Save.

Deploying Always On VPN with Intune using Custom ProfileXML

Demonstration Video

A demonstration video with guidance for deploying a Windows 10 Always On VPN user tunnel using the native Microsoft Intune UI as well as custom ProfileXML can be found here. The custom ProfileXML guidance starts at 7:52.

Additional Information

Deploying Windows 10 Always On VPN with Microsoft Intune

Deploying Windows 10 Always On VPN Device Tunnel using PowerShell

Windows 10 Always On VPN IKEv2 Security Configuration

Windows 10 Always On VPN LockDown Mode

Windows 10 Always On VPN Scripts and Sample ProfileXML Files on GitHub

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