Entra Global Secure Access (GSA) Client Intune Deployment PowerShell Script

The Microsoft Entra Global Secure Access (GSA) client is commonly deployed using Microsoft Intune. To deploy the client as an Intune Win32 app, administrators package the installer and a PowerShell installation script into an .intunewin file. Microsoft provides a sample PowerShell script that creates a log, configures Windows to prefer IPv4 over IPv6, and launches the installer. However, the sample has several limitations that can make it unreliable in production environments. To address these shortcomings, I’ve refactored the code to make it more robust and better aligned with enterprise deployment best practices.

Script Improvements

Microsoft’s PowerShell script for installing the GSA client has several significant limitations. My refactored version includes the following improvements.

  1. Preserved the existing DisabledComponents setting. Microsoft’s example overwrites the entire registry value, potentially removing previously configured settings. My version sets the 0x20 bit to prefer IPv4 while preserving any other flags already present.
  2. Validates the installer’s Authenticode signature. My revised script verifies that the installer has a valid Authenticode signature and that the signing certificate identifies Microsoft Corporation as the publisher.
  3. Preserves the pending reboot state. My script records when the registry setting was changed and compares that timestamp with the device’s last boot time. If the device has not restarted, subsequent runs continue to return exit code 3010, even if an earlier installation attempt failed.
  4. Expanded exit-code handling. The script writes a timestamped PowerShell transcript to the Intune Management Extension log directory, allowing it to be included with collected Intune diagnostics. Logging failures do not prevent the installation from continuing.
  5. Intune-integrated logging. I’ve updated the script’s logging to use the Intune Management Extensions logs folder, so logs are captured by Intune’s diagnostics collection. Each run of the script generates its own timestamped log file, making troubleshooting easier. Also, logging failures never block installation.
  6. Best practice alignment. I’ve added comment-based help, culture-invariant timestamps, and a $PSScriptRoot guard with a clean error to handle script execution issues. In addition, the script is digitally signed to support environments that enforce signed-script execution policies.

GitHub

I’ve published my refactored GSA client installation script on GitHub. You can download the script here:

https://github.com/richardhicks/gsa/blob/main/Install-GSAClient.ps1

Note: The script expects the installer to be named GlobalSecureAccessInstaller.exe. However, downloaded installers typically include the version number in the filename, such as GlobalSecureAccessInstaller_<version>.exe. Before creating the .intunewin package, either rename the installer or update the $InstallerName variable in the script.

Contribute

Suggestions and contributions are welcome. If you have ideas for making the GSA client deployment more robust or reliable, please submit a pull request on GitHub.

Summary

Microsoft provides a PowerShell script to deploy the Entra GSA client via Intune, but it has several limitations. This refactored version preserves existing registry settings, validates the installer, improves reboot and exit-code handling, integrates logging with Intune diagnostics, and better aligns with enterprise deployment best practices.

Additional Information

Install-GSAClient.ps1 PowerShell Script on GitHub

Prepare Win32 App Content for Upload to Microsoft Intune

Install the Global Secure Access Client for Microsoft Windows

Windows Server DHCP and Option 108

While enterprise adoption of IPv6 has been slow, it is still moving forward. For example, the U.S. federal government has mandated [M-21-07 – PDF] the transition to IPv6 to modernize its networks and enhance security, scalability, and interoperability. During the migration to IPv6, most systems will be configured with both IPv4 and IPv6, a configuration referred to as dual stack. Ultimately, the goal is the elimination of IPv4 entirely and the use of IPv6 exclusively. However, IPv6-only presents some unique challenges.

Access to IPv4

Although an organization can successfully migrate to IPv6-only networks internally, they do not control networks outside its boundaries. In some cases, a host on an IPv6-only network may need to communicate with an IPv4 resource. Administrators must deploy an IPv6 transition technology to support this scenario.

464XLAT

464XLAT, defined in RFC 6877, is a network architecture that facilitates the transition from IPv4 to IPv6 by enabling IPv4 traffic to operate over an IPv6-only network. It combines two translation mechanisms: a client-side translator (CLAT) on the user device, which converts IPv4 packets to IPv6, and a provider-side translator (PLAT) at the network edge, which converts the IPv6 packets back to IPv4 to communicate with IPv4-only internet services. This dual-translation approach allows devices in an IPv6-only environment to access both IPv6 and IPv4 resources without requiring a full IPv4 stack, making it an efficient solution for networks transitioning to IPv6 while maintaining compatibility with legacy IPv4 systems. To support 464XLAT, Windows provides specific functionality for CLAT, though with some limitations.

CLAT for Windows

Windows currently provides CLAT support only for cellular network interfaces. CLAT is not available for Wi-Fi or Ethernet interfaces today. However, Microsoft has publicly announced plans to extend CLAT support in Windows for these non-cellular network interfaces soon.

IPv6 Mostly

IPv6 Mostly, defined in RFC 8925, refers to a network configuration where IPv6 is the primary protocol for communication, but IPv4 is still supported for specific use cases. Devices in these networks prefer IPv6 for most operations, leveraging its larger address space and modern features, while maintaining limited IPv4 compatibility. IPv6 Mostly networks ease the transition from IPv4 to IPv6, balancing modern protocol adoption with support for older applications. They optimize resource usage and prepare networks for a future where IPv6 dominates, with tools like 464XLAT providing seamless IPv4 access when necessary.

DHCP Option 108

DHCP Option 108 is a specific configuration in DHCP that enables IPv6-only networks to signal clients to disable IPv4. When a client receives this option, it deactivates its IPv4 stack, relying solely on IPv6 for communication. Turning off IPv4 when it isn’t needed helps streamline network operations in IPv6-focused environments.

Option 108 and Windows Server DHCP

Commercial DHCP appliances like Infoblox and many open source DHCP platforms natively support DHCP option 108. However, no supported version of Windows Server, including the latest release (Windows Server 2025), supports DHCP option 108 natively. To enable DHCP option 108 on Windows DHCP servers, administrators can create a custom predefined option.

Custom Predefined Option

To create a custom predefined option for DHCP option 108 on a Windows DHCP server, open the DHCP management console (dhcpmgmt.msc) and perform the following steps.

  1. Right-click IPv4 and choose Set Predefined Options.
  2. Click Add.
  3. Enter IPv6 Only Preferred in the Name field.
  4. Select Long from the Data type drop-down list.
  5. Enter 108 in the Code field.
  6. Click Ok.

Assigning DHCP Option 108

Once complete, perform the following steps to assign DHCP option 108 to a DHCP scope.

  1. Select an IPv4 DHCP scope.
  2. Right-click Scope Options and choose Configure Options.
  3. Select 108 IPv6 Only Preferred from the Available Options list.
  4. Enter a value in seconds, in hexadecimal format. This value represents the duration for which a client should prefer IPv6-only mode. For example, 86,400 seconds (1 day) is 0x15180.
  5. Click Ok.

PowerShell

Custom predefined options can also be configured using PowerShell.

Custom Predefined Option

To create a custom predefined option for DHCP option 108, open an elevated PowerShell command on a Windows DHCP server and run the following command.

Add-DhcpServerv4OptionDefinition -Name ‘IPv6 Only Preferred’ -OptionId 108 -Type DWORD -PassThru

Assigning DHCP Option 108

To assign the custom predefined DHCP option 108 to a DHCP scope, run the following PowerShell command.

Set-DhcpServerv4OptionValue -ScopeId 172.16.5.0 -OptionId 108 -Value 0x15180 -PassThru

DHCP Offer

Once configured, if the client indicates support for DHCP option 108 in its DHCP Request, the DHCP server will include it in the DHCP Offer, as shown here.

Learn More

If you are interested in learning more about IPv6 Mostly and DHCP option 108, be sure to listen to the following episodes of the IPv6 Buzz Podcast.

Summary

As organizations continue their transition toward IPv6, DHCP option 108 provides administrators with a simple and effective way to reduce reliance on legacy IPv4 by signaling clients to prefer IPv6-only operation if they can support it. While Windows Server does not natively support this option, creating a custom predefined setting ensures administrators can take advantage of this important feature.

Additional Information

M-21-07 – Completing the Transition to IPv6 for U.S. Federal Government Agencies [PDF]

Microsoft Plans to Extend CLAT Support in Windows 11

RFC 6877 – 464XLAT: Combination of Stateful and Stateless Translation

RFC 8925 – IPv6-Only Preferred Option for DHCPv4

IPv6 Buzz Podcast on PacketPushers.Net

Always On VPN Client IP Address Assignment Methods

When Always On VPN clients connect to the VPN server, they must be assigned an IP address to facilitate network communication. When using Windows Server and Routing and Remote Access Service (RRAS) for VPN services, administrators must choose between Dynamic Host Configuration Protocol (DHCP) and static address pool assignment methods.

DHCP

DHCP is a quick and easy way to handle VPN client IP address assignment. However, there are some drawbacks and limitations associated with this option. Consider the following.

Allocation

DHCP for Always On VPN clients does not work as you might expect. For example, when a VPN client connects, it does not obtain its IP address directly from the DHCP server. Instead, the VPN server leases a block of IP addresses from the DHCP server and manages those on behalf of its clients. On the DHCP server, you will see the Unique ID column of these IP address leases indicating RAS.

Address Block Size

After configuring the VPN server to use DHCP VPN client IP address assignment, the VPN server will automatically lease a block of ten IP addresses from a DHCP server. When this initial block of ten IP addresses is exhausted, the VPN server will lease another block of ten IP addresses. Administrators can increase the size of the requested address block by creating the following registry key on each VPN server.

Key: HKLM\SYSTEM\CurrentControlSet\Services\RemoteAccess\Parameters\IP
Value: InitialAddressPoolSize
Type: DWORD
Data: <size of DHCP pool request>

Alternatively, administrators can download Update-VpnServerDhcpPoolSize.ps1 from my GitHub repository and run it on each VPN server to increase the size of the initial DHCP address pool request.

DHCP Options

The VPN server discards all DHCP option information returned by the DHCP server. The VPN server uses only the IP address from the DHCP lease. The client is unaware of any other information in the DHCP lease.

Subnet

By default, the VPN server will only request DHCP addresses from a scope that matches the same subnet as the IP address assigned to the VPN server’s network adapter. If the VPN server has more than one network interface, it will send DHCP requests from the network interface listed on the Adapter drop-down list, as shown here.

Note: This option is only available on servers configured with multiple network interfaces. Also, if the value is set to Allow RAS to select adapter, it is best to specifically define the network interface where DHCP and DNS requests are made.

Scope Size

When using the DHCP assignment method, ensure the DHCP scope contains enough IP addresses to support the number of concurrent connections expected on all VPN servers.

IPv6

DHCPv6 is not supported on RRAS for VPN client IP address assignment. The only option for IPv6 is prefix assignment.

RRAS in Azure

DHCP is not supported when deploying RRAS in Azure. Administrators deploying RRAS in Azure to support Always On VPN must use the static address pool assignment method. More details here.

Known Issues

When using DHCP with Windows Server 2019 RRAS servers, a known issue prevents this from working correctly. Administrators can download Update-VpnServerDhcpPrivileges.ps1 from my GitHub repository and run it on each VPN server to ensure proper DHCP operation.

Increased Complexity

Since the VPN server leases IP addresses on behalf of clients and discards DHCP option information included in the lease, there’s no real benefit to using DHCP. Using DHCP only adds complexity and introduces another dependency, making the solution more brittle and difficult to manage. Using the static address pool assignment method is a better choice.

Static Pool

Implementation best practices dictate using the static address pool assignment method instead of DHCP. The following is guidance for configuring RRAS to support the static address pool option for VPN client IP address assignment.

Unique Subnet

Using a unique IP subnet is best when using the static address pool assignment method. However, this also requires configuring internal network routing to return traffic for that subnet to the individual VPN server where that subnet is assigned. Each server must have a unique IP address pool assigned. Define static address pools using subnet boundaries when configuring multiple VPN servers. Assigning IP address pools along subnet boundaries simplifies internal network routing configuration. Ensure that assigned IP address pool subnets are large enough to accommodate the total number of concurrent connections expected on each server. Be sure to overprovision to handle failover scenarios.

Same Subnet

Alternatively, administrators can assign VPN client IP addresses from the same subnet as the VPN server’s network interface. Assigning VPN client IP addresses from the same subnet as the VPN server eliminates the need for any internal network routing configuration, simplifying deployment. However, server subnets are often small and may not have enough IP address space to support numerous concurrent VPN connections. Be sure to plan accordingly.

Static IP Addresses

It is possible to assign a static IP address to an individual user. However, assigning a static IP address to a specific device is not. I will discuss static IP address assignments for Always On VPN clients in a future blog post.

Other Limitations

Here are some additional things to consider when creating a VPN client IP addressing strategy.

DNS

Always On VPN clients can be configured to register their IP address in DNS. However, the VPN client configuration controls this setting. The DHCP server does not register IP addresses in DNS when using DHCP. The client registers its IP address in DNS directly after it connects. In addition, a VPN client will receive a different IP address each time it connects to the VPN server. DNS propagation can delay hostname resolution on-premises for remote-connected VPN clients.

Selective Addressing

Regardless of which assignment method is selected, assigning different IP addresses to different types of connections is not possible. For example, a common ask is to assign user connections from one IP address pool and device connections from another. The only option to support this is to use different servers for each type of connection.

Summary

The best practice for IPv4 VPN client addressing is to use the static address pool method with a unique IPv4 subnet per server. Using static address pool assignment provides the most flexible configuration options and eliminates the dependency on internal services, making the solution more resilient and easier to manage. A unique address pool per server ensures that a large enough subnet can be defined to support the expected number of concurrent connections, regardless of the subnet size the VPN server is assigned to. Also, a unique IP subnet for VPN clients makes configuring internal firewall rules to control VPN client access easier.

Additional Information

Always On VPN and IPv6

Always On VPN Client DNS Server Configuration

Always On VPN Routing Configuration

Always On VPN RRAS Internal Interface Non-Operational