Always On VPN SSTP with Let’s Encrypt Certificates

Always On VPN SSTP Security Configuration

When configuring the Windows Server Routing and Remote Access Service (RRAS) to support Secure Socket Tunneling Protocol (SSTP) for Always On VPN user tunnel connections, administrators must install a Transport Layer Security (TLS) certificate on the VPN server. The best practice is to use a certificate issued by a public Certification Authority (CA). In addition, administrators should use a TLS certificate using Elliptic Curve Digital Signature Algorithm (ECDSA) for optimal security and performance.

Let’s Encrypt

Obtaining a public TLS certificate is not inherently difficult, nor is it expensive. However, Let’s Encrypt is a nonprofit public CA issues TLS certificates entirely for free. Always On VPN supports Let’s Encrypt TLS certificates, and installing a Let’s Encrypt certificate on the Always On VPN RRAS server is quite simple.

Pros and Cons

Using Let’s Encrypt certificates for Always On VPN has several significant advantages over traditional public CAs.

  • Cost – Let’s Encrypt certificates are free! No cost whatsoever.
  • Speed – Enrolling for a Let’s Encrypt certificate takes just a few minutes.
  • Trusted – Let’s Encrypt certificates are trusted by default in Windows 10 and Windows 11.

Let’s Encrypt is not without some drawbacks, however.

  • Lifetime – Let’s Encrypt certificates are only valid for 90 days.
  • Administration – Certificates must be redeployed frequently (every 90 days).
  • Security – PFX files (which include private keys) are left on disk by default.

It is possible to mitigate some of these drawbacks, though. For example, deleting PFX files after import can improve security. Alternatively, using a Certificate Signing Request (CSR) eliminates PFX files completely.

Also, it is possible to fully automate the Let’s Encrypt certificate enrollment and RRAS configuration process, which eases the administrative burden. And rotating certificates every 90 days could be considered an advantage from a security perspective! Enrolling new certificates (and specifically certificates with unique keys) is advantageous in that respect.

Certificate Enrollment

There are several different ways to enroll for Let’s Encrypt certificates. The preferred method is using PowerShell, as it works on both Windows Server with Desktop Experience (GUI) and Windows Server Core. Using PowerShell, administrators can also fully automate the enrollment and assignment of the certificate in RRAS.

PowerShell Module

To enroll for Let’s Encrypt TLS certificates on the VPN server, install the Posh-ACME PowerShell module. On the RRAS server, open an elevated PowerShell window and run the following command.

Install-Module Posh-ACME

Certificate Request

After installing the Posh-ACME PowerShell module, select a Let’s Encrypt environment by running the following command. Use LE_PROD for the production Let’s Encrypt server or LE_STAGE for the staging environment (used for testing).

Set-PAServer LE_PROD

Next, request a new certificate using the following command.

New-PACertificate -Domain vpn.example.net -Contact ‘[email protected]’ -CertKeyLength ec-256 -AcceptTOS -Install

The administrator is prompted to create a TXT record in public DNS to prove ownership of the domain. Using the example above, create a DNS record called _acme-challenge.vpn in the example.net DNS zone.

Once complete, the TLS certificate is automatically installed in the local computer certificate store on the VPN server and can be assigned in the RRAS management console, as shown here.

Note: R3 is a Let’s Encrypt issuing certification authority.

DNS Plugin

The Posh-ACME PowerShell module supports DNS plugins that allow administrators to automate the creation of the DNS TXT record used to authorize certificate enrollment. DNS plugins for many public DNS providers are available. Some of the more popular DNS providers are listed here.

  • Microsoft Azure
  • Amazon Route53
  • Cloudflare
  • Akamai
  • GoDaddy
  • Infoblox
  • Windows Server

A list of all supported DNS plugins for Posh-ACME can be found here.

Certificate Binding

Administrators can use the following PowerShell example code to automate the process of binding the new TLS certificate to the SSTP listener in RRAS.

$Thumbprint = <TLS certificate thumbprint>
$Cert = Get-ChildItem -Path Cert:\LocalMachine\My\$thumbprint
Set-RemoteAccess -SslCertificate $Cert
Restart-Service RemoteAccess -Passthru

Additional Information

Posh-ACME Tutorial

Windows 10 Always On VPN TLS Certificate Requirements for SSTP

Windows 10 Always On VPN SSTP Security Configuration

Always On VPN Book Available for Pre-Order

Great news! My new book, Implementing Always On VPN, is now available for pre-order on Amazon.com. This new book, scheduled for release in late 2021, is a comprehensive implementation guide for Windows 10 Always On VPN. Drawing on many years of experience deploying Always On VPN for organizations worldwide, it covers all aspects of an Always On VPN deployment, including planning and design, prerequisite gathering, infrastructure preparation, and client deployment.

In addition, it contains detailed, prescriptive guidance for advanced configuration options such as application and traffic filtering and proxy server configuration. Cloud deployments using Azure VPN gateway and Virtual WAN are covered, and it includes guidance for configuring Azure MFA and Conditional Access.

Also, the book includes thorough guidance for provisioning certificates using Microsoft Endpoint Manager/Intune using both PKCS and SCEP. It outlines options for high availability for VPN and authentication infrastructure and provides details for ongoing system maintenance and operational support.

Finally, the book has an entire chapter dedicated to troubleshooting and resolving common (and not so common!) issues encountered with Windows 10 Always On VPN.

Reserve your copy today. Pre-order Implementing Always On VPN now!

Chapter List

  1. Always On VPN Overview
  2. Plan an Always On VPN Deployment
  3. Prepare the Infrastructure
  4. Configure Windows Server for Always On VPN
  5. Provision Always On VPN clients
  6. Advanced Configuration
  7. Cloud Deployments
  8. Deploy Certificates with Intune
  9. Integrating Azure MFA
  10. High Availability
  11. Monitor and Report
  12. Troubleshooting

Always On VPN Short Name Access Failure

Using Microsoft Endpoint Manager (Intune), administrators can provision Always On VPN to devices that are Azure AD joined only. Users accessing on-premises resources from these devices can still use seamless single sign-on, making this deployment option popular for organizations moving to the cloud.

Short Names

After deploying Always On VPN to Windows 10 devices that are Azure AD joined only and configured to use client certificate authentication, administrators may find that users cannot access on-premises resources by their short name, such as \\app1. The connection fails and returns the following error message.

“Windows can’t find <servername/sharename>. Check the spelling and try again.”

FQDN

Interestingly, on-premises resources are accessible using their fully qualified domain name (FQDN), such as \\app1.corp.example.net.

Troubleshooting

Testing name resolution using the short name works as expected, and the resource is reachable at the network layer, as shown here.

Workaround

This issue is related to how Windows performs authentication when connected via VPN. To resolve this issue, edit the rasphone.pbk file and change the value of UseRasCredentials to 0. Rasphone.pbk can be found in the $env:AppData\Microsoft\Network\Connections\Pbk folder.

After updating this setting, restart the VPN connection for the change to take effect.

Proactive Remediations

While helpful for testing, editing rasphone.pbk manually obviously does not scale well. To address this, consider using Intune Proactive Remediations. Intune Proactive Remediations allows administrators to deploy detection and remediation PowerShell scripts to monitor specific settings and update them if or when they change. Proactive Remediations will ensure the setting is applied consistently across all managed endpoints.

GitHub Repository

I have created a new GitHub repository dedicated to PowerShell scripts for Endpoint Manager Proactive Remediations for Always On VPN. There you will find detection and remediation scripts for the UseRasCredentials settings change described in this article.

Additional Information

Always On VPN Endpoint Manager Proactive Remediation Scripts on GitHub

Endpoint Manager Proactive Remediations Tutorial

Always On VPN Authentication Failure with Azure Conditional Access

Always On VPN Clients Prompted for Authentication when Accessing Internal Resources

Integrating Microsoft Azure Conditional Access with Windows 10 Always On VPN has several important benefits. The most important is that it allows administrators to improve their security posture by enforcing access polices that can be dynamically applied. For example, requiring multifactor authentication (MFA) for privileged users (e.g., administrators) or sign-ins that appear to be risky, the type of device they are connecting with, the health of the endpoint, and much more.

Authentication Failure

When configuring Always On VPN to support Azure Conditional Access, administrators may expeirence a failed authentication during preliminary testing. Specifically, an event ID 20227 from the RasClient source may be encountered with the following error message.

“The user <username> dialed a connection named <connection name> which has failed. The error code returned on failure is 812.”

Looking at the event logs on the Network Policy Server (NPS) server reveals an event ID 6273 from the Microsoft Windows security auditing source with Reason Code 258 and the following Reason.

“The revocation function was unable to check revocation for the certificate.”

Root Cause

When Azure Conditional Access is configured for Always On VPN, a short-lived certificate (1 hour lifetime) is provisioned by Azure. This certificate does not include revocation information because, by design, a short-lived certificate does not need to be revoked. However, by default NPS always checks revocation when client authentication certificates are used for authentication. Since the certificate does not include this information, certificate revocation fails.

Resolution

The way to resolve this issue is to disable certificate revocation checking for Protected Extensible Authentication Protocol (PEAP) authentication requests. To do this, open an elevated PowerShell window on the NPS server and run the following command.

New-ItemProperty -Path ‘HKLM:\SYSTEM\CurrentControlSet\Services\RasMan\PPP\EAP\13\’ -Name IgnoreNoRevocationCheck -PropertyType DWORD -Value 1 -Force

Once complete, restart the NPS server for the changes to take effect.

Additional Information

Windows 10 Always On VPN Network Policy Server (NPS) Load Balancing

Windows 10 Always On VPN Network Policy Server (NPS) Server 2019 Bug

Always On VPN and Zero Trust Network Access (ZTNA)

Always On VPN and Zero Trust Network Access (ZTNA)

Zero Trust Network Access (ZTNA) is a term that administrators are likely familiar with, as it is one of the hottest marketing buzzwords in circulation today. ZTNA can mean different things depending on the deployment scenario. ZTNA is fundamentally about enforcing the principle of least privilege for endpoints connecting remotely to the corporate network when it comes to enterprise mobility and remote access.

Trusted Access

Historically, VPNs and even DirectAccess granted full, unrestricted network access to authenticated devices and users. Once the endpoint has an IP address, and in the absence of other controls (routing limitations, firewall access controls, etc.), the user could access any resource on the internal network. The rationale was that authenticated devices and users should be considered “trusted”.

Limitations

The Trusted Access model has some significant limitations. It assumes that all traffic from authorized users and devices is legitimate. However, if an endpoint is compromised, an attacker has broad access to the internal network, which is not ideal from a security perspective.

Zero Trust

Zero Trust Network Access is a concept where administrators define explicitly the minimum level of access required to support remote workers. Instead of granting full network access to the endpoint, controlling access using fine-grained policies is enforced on the VPN connection. Configuring limited network access for Always On VPN clients dramatically reduces exposure of the internal network to compromised endpoints.

ZTNA Management

There is a significant management burden associated with this approach, however. Administrators must identify each application requiring VPN access and determine all associated protocols and ports to be allowed, and internal resources to which they will communicate. Although this task isn’t difficult if clients require access to a small subset of internal resources, it can be a substantial undertaking if clients require access to many internal resources from numerous client applications.

Moving Targets

Making things more challenging is that application and network infrastructure often change constantly, requiring administrators to manage network access continually to ensure application availability. When adding new applications or changing the internal infrastructure, updating the configuration on all remote endpoints will be required.

Updating Always On VPN configuration for devices managed with Microsoft Endpoint Manager (formerly Intune) isn’t difficult. However, it can be more challenging when using PowerShell with System Center Configuration Manager (SCCM) or another endpoint management platform.

Traffic Filters

ZTNA can be configured with Always On VPN using Traffic Filters. With Traffic Filters, administrators can apply fine-grained access control for VPN traffic based on a combination of the following.

  • Source IP address (IP address, address range, or subnet)
  • Destination IP address (IP address, address range, or subnet)
  • Protocol (TCP, UDP, IP, etc.)
  • Source Port
  • Destination Port

Endpoint Manager Configuration

Configuring Traffic Filters for Always On VPN connections can be performed using Microsoft Endpoint Manager. Open the Endpoint Manager management console (https://endpoint.microsoft.com), navigate to the Always On VPN device configuration profile, then perform the following steps.

  1. Expand App and Traffic Rules.
  2. Click Add next to Network traffic rules for this VPN connection.
  1. Enter a descriptive name in the Name field.
  2. Select Split tunnel from the Rule type drop-down list.
  3. Enter “6” in the Protocol field.
  4. Enter “3389” in the Lower port and Upper port fields in the Remote port ranges section.
  5. Enter an IPv4 address in the Lower IPv4 address field.
  6. Enter an IPv4 address in the Upper IPv4 address field. Enter the same IPv4 address as the lower address to specify a single host.
  7. Click Save.

The example above shows a traffic filter restricting access to TCP port 3389 (Remote Desktop Protocol) from all VPN clients to the 172.16.0.0/24 network.

Note: Repeat these steps to create as many traffic filters as required for any processes or applications that must communicate over the Always On VPN connection.

XML Configuration

Traffic Filters can also be configured using custom XML. To implement the same Traffic Filter described previously, add the following code between the <VPNProfile> and </VPNProfile> tags in your XML configuration file.

<TrafficFilter>
   <Protocol>6</Protocol>
   <RemotePortRanges>3389</LocalPortRanges>
   <RemoteAddressRanges>172.16.0.0/24</RemoteAddressRanges>
</TrafficFilter>

Note: Address ranges used in Traffic Filters can be defined using CIDR notation in XML, but they are not supported using Microsoft Endpoint Manager today.

Default Deny

When configuring a Traffic Filter for an Always On VPN profile, an implicit “deny all” rule is automatically enabled. Any traffic not explicitly defined in a Traffic Filter will be denied, including unsolicited inbound traffic, which has crucial implications for the device tunnel because it is used commonly for system management of remote devices.

Direction

Traffic Filters are enabled for the Outbound direction only, by default. Beginning with Windows 10 2004, Microsoft introduced support for Inbound traffic filters. Before Windows 10 2004, configuring a Traffic Filter on the device tunnel would break manage-out scenarios by denying all unsolicited inbound network access.

As of this writing, configuring inbound Traffic Filters using Microsoft Endpoint Manager is not supported. They are only configurable using custom XML.

To implement a Traffic Filter to allow inbound RDP access from the internal network over the device tunnel, add the following code between the <VPNProfile> and </VPNProfile> tags in your XML configuration file.

<TrafficFilter>
   <Protocol>6</Protocol>
   <LocalPortRanges>3389</LocalPortRanges>
   <RemoteAddressRanges>172.16.0.0/16</RemoteAddressRanges>
   <Direction>Inbound</Direction>
</TrafficFilter>

Note: When configuring inbound Traffic Filters, specify the port of the listening process or application using the LocalPortRanges field.

Application Filters

Administrators can combine Application Filters with Traffic Filters to control network access over the Always On VPN connection even more granularly. Applications can be defined by the following.

  • Package Family Name (PFN) – This is the unique name of a Microsoft Store application. Use the Get-AppxPackage PowerShell command to find the PFN for an application.
  • File Path – This is the full path to any executable on the file system. For example, c:\Windows\System32\mstsc.exe.
  • SYSTEM – This allows Windows kernel-mode drivers (such as ping.exe and net.exe) to send traffic over the Always On VPN connection.

As of this writing, configuring Application Filters using Microsoft Endpoint Manager is not supported. They are only configurable using custom XML.

Application Filter Examples

Below are three examples showing different Application Filters based on file path, Package Family Name, and SYSTEM.

File Path

This example shows a Traffic Filter configured to allow RDP access to an internal subnet using the native Windows Remote Desktop client (mstsc.exe).

<TrafficFilter>
   <App>
      <Id>C:\Windows\System32\mstsc.exe</Id>
   </App>
   <Protocol>6</Protocol>
   <RemotePortRanges>3389</RemotePortRanges>
   <RemoteAddressRanges>172.16.0.0/24</RemoteAddressRanges>
</TrafficFilter>

Package Family Name

This example shows a Traffic Filter configured to allow RDP access to an internal subnet using the Microsoft Windows Store Remote Desktop client.

<TrafficFilter>
   <App>
      <Id>Microsoft.RemoteDesktop_8wekyb3d8bbwe</Id>
   </App>
   <Protocol>6</Protocol>
   <RemotePortRanges>3389</RemotePortRanges>
   <RemoteAddressRanges>172.16.0.0/24</RemoteAddressRanges>
</TrafficFilter>

SYSTEM

This example shows a Traffic Filter configured to allow the netsh.exe process access to an internal subnet.

<TrafficFilter>
   <App>
      <Id>SYSTEM</Id>
   </App>
   <Protocol>6</Protocol>
   <RemotePortRanges>445</RemotePortRanges>
   <RemoteAddressRanges>172.16.0.0/24</RemoteAddressRanges>
</TrafficFilter>

This example shows a Traffic Filter configured to allow the ping.exe process access to an internal subnet.

<TrafficFilter>
   <App>
      <Id>SYSTEM</Id>
   </App>
   <Protocol>1</Protocol>
   <RemoteAddressRanges>172.16.0.0/24</RemoteAddressRanges>
</TrafficFilter>

Note: Ping uses ICMP (IP protocol 1), which is a network layer protocol. As such, defining ports for the filter is not required.

IPv6 Compatibility

Sadly, the filtering techniques described in this article do not work when also configuring IPv6 on the Always On VPN connection. As of this writing, enabling Traffic Filters when an IPv6 address is assigned to the VPN interface is not supported. More details can be found here.

Always On VPN Traffic Filters and IPv6

Summary

Configuring Zero Trust Network Access (ZTNA) with Windows 10 Always On VPN is not trivial. Still, with attention to detail, it can be a highly effective tool to enforce fine-grained network access policies and reduce exposure of the internal network to compromised endpoints. Combining Traffic Filters with Application Filters allows administrators to tightly control Always On VPN access and ensure the principle of least privilege is applied.

Additional Information

Windows 10 Always On VPN Traffic Filters and IPv6

Windows 10 Always On VPN User Tunnel XML Configuration Reference File

Windows 10 Always On VPN Device Tunnel XML Configuration Reference File

Windows 10 Always On VPN VPNv2 CSP Reference

IP Protocol Numbers

Always On VPN Traffic Filters and IPv6

Always On VPN Windows Server RRAS Service Does Not Start

Using Traffic Filters with Always On VPN provides administrators the option to configure a true Zero Trust Network Access (ZTNA) solution for their field-based users and devices. By enabling traffic filtering, network access over the Always On VPN connection can be controlled using fine-grained policies. Traffic Filter rules can be configured to restrict access based source and destination IP addresses, protocols, and source and destination ports. Administrators can further restrict access based on the application generating the traffic.

IPv6

While testing these features recently, I learned that the Microsoft Endpoint Manager (formerly Intune) user interface does not appear to support IPv6 when configuring traffic filter rules. As you can see here, the UI explicitly asks for an IPv4 address and complains when entering an IPv6 address in the address field, as shown here.

Interestingly, it is possible to add IPv6 addresses in XML, as follows.

<TrafficFilter>
   <App>
      <Id>Microsoft.RemoteDesktop_8wekyb3d8bbwe</Id>
   </App>
   <Protocol>6</Protocol>
   <RemotePortRanges>3389</RemotePortRanges>
   <RemoteAddressRanges>2001:470:f109::/48</RemoteAddressRanges>
</TrafficFilter>

Connection Failure

Unfortunately, after loading the XML on a test client, the Always On VPN connection fails with the following error message.

“Can’t connect to <ConnectionName>. Catastrophic failure.”

In addition, the Application event log records an event ID 20227 from the RasClient source with the following error.

“The user <UserName> dialed a connection name <ConnectionName> which has failed. The error code returned on failure is -2147418113.”

Workaround

At this time, the only known workaround is to update the configuration on the RRAS server to use IPv4 addressing for VPN clients.

Summary

Unfortunately, IPv6 is still a second-class citizen when it comes to Always On VPN. Although enabling IPv6 works well in most common deployment scenarios, the Microsoft Endpoint Manager management console often fails to accept IPv6 entries in IP address fields. In addition, some advanced features such as traffic filtering are incompatible with IPv6.

Additional Information

Windows 10 Always On VPN and Zero Trust Network Access (ZTNA)

Windows 10 Always On VPN Windows Server RRAS Service Does Not Start

Always On VPN Updates for RRAS and IKEv2

Always On VPN Updates for RRAS and IKEv2

Many users have reported connection stability issues using Windows Server 2019 Routing and Remote Access Service (RRAS) and the IKEv2 VPN protocol. Specifically, there have been reports of random disconnects for which the connection cannot be re-established for an extended period. At the same time, other VPN connections may work without issue.

KB5003703

Microsoft has identified an issue in RRAS where the RemoteAccess service enters DoS protection mode, limiting incoming IKEv2 connection attempts. They released an update on June 15 (OS Build 17763.2028) that addresses this issue. Previously, the only workaround was to restart the IKEEXT service, which was highly disruptive if performed during peak hours.

No More Files

In addition, this update includes another Always On VPN-related fix for Windows 10 1809 clients. An Always On VPN user tunnel connection may fail, with an error message stating, “There are no more files.” The problem can occur after an existing user’s certificate is automatically renewed.

Additional Information

Microsoft Update June 15, 2021 KB5003703 (OS Build 17763.2028)

Always On VPN SSTP Security Configuration

Always On VPN SSTP Security Configuration

When using Windows Server Routing and Remote Access Service (RRAS) to terminate Always On VPN client connections, administrators can leverage the Secure Socket Tunneling Protocol (SSTP) VPN protocol for client-based VPN connections. SSTP is a Microsoft proprietary VPN protocol that uses Transport Layer Security (TLS) to secure connections between the client and the VPN gateway. SSTP provides some crucial advantages over IKEv2 in terms of operational reliability. It uses the TCP port 443, the standard HTTPS port, which is universally available and ensures Always On VPN connectivity even behind highly restrictive firewalls.

TLS Certificate

When configuring SSTP, the first thing to consider is the certificate installed on the server. A certificate with an RSA key is most common, but for SSTP, provisioning a certificate with an ECDSA key is recommended for optimal security and performance. See the following two articles regarding SSTP certificate requirements and ECDSA Certificate Signing Request (CSR) creation.

Always On VPN SSL Certificate Requirements for SSTP

Always On VPN ECDSA SSL Certificate Request for SSTP

TLS Configuration

Much like IKEv2, the default TLS security settings for SSTP are less than optimal. However, SSTP can provide excellent security with some additional configuration.

TLS Protocols

There are several deprecated TLS protocols enabled by default in Windows Server. These include SSLv3.0, TLS 1.0, and TLS 1.1. They should be disabled to improve security for TLS. To do this, open an elevated PowerShell window on the VPN server and run the following commands.

New-Item -Path ‘HKLM:\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\SSL 3.0\Server\’ -Force

New-ItemProperty -Path ‘HKLM:\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\SSL 3.0\Server\’ -Name Enabled -PropertyType DWORD -Value ‘0’

New-Item -Path ‘HKLM:\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.0\Server\’ -Force

New-ItemProperty -Path ‘HKLM:\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.0\Server\’ -Name Enabled -PropertyType DWORD -Value ‘0’

New-Item -Path ‘HKLM:\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.1\Server\’ -Force

New-ItemProperty -Path ‘HKLM:\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.1\Server\’ -Name Enabled -PropertyType DWORD -Value ‘0’

Cipher Suites

Many weak TLS cipher suites and enabled by default in Windows Server. To further enhance security and performance, they can be optimized using a tool such as IIS Crypto. For example, consider prioritizing cipher suites that use ECDHE and GCM with ECDSA to improve security. Also, remove ciphers that use AES-256 to enhance scalability and performance.

Note: AES-256 does not provide any additional practical security over AES-128. Details here.

PowerShell Script

I have published a PowerShell script on GitHub that performs security hardening and TLS cipher suite optimization to streamline the configuration TLS on Windows Server RRAS servers. You can download the script here.

Validation Testing

After running the script and restarting the server, visit the SSL Labs Server Test site to validate the configuration. You should receive an “A” rating, as shown here.

Note: An “A” rating is not achievable on Windows Server 2012 or Windows Server 2012 R2 when using an RSA TLS certificate. A TLS certificate using ECDSA is required to receive an “A” rating on these platforms.

Additional Information

Always On VPN SSL/TLS Certificate Requirements for SSTP

Always On VPN ECDSA SSL Certificate Request for SSTP

Qualys SSL Labs Server Test Site

Always On VPN Protocol Recommendations for Windows Server RRAS

Microsoft SSTP Specification on MSDN

Always On VPN and Autopilot Hybrid Azure AD Join

Always On VPN and Autopilot Hybrid Azure AD Join

Windows Autopilot is a cloud-based technology that administrators can use to configure new devices wherever they may be, whether on-premises or in the field. Devices provisioned with Autopilot are Azure AD joined by default and managed using Microsoft Endpoint Manager. Optionally, an administrator can enable hybrid Azure AD join by also joining the device to an on-premises Active Directory domain using a domain join configuration profile in conjunction with the offline domain-join connector. Although enabling hybrid Azure AD join might sound appealing, there are specific deployment scenarios that present some rather unique and challenging problems when using this option.

Offline Hybrid Azure AD Join

For field-based devices, the device must have connectivity to a domain controller to support the initial login when the user has no local cached credentials. The Always On VPN device tunnel can be deployed in this scenario to provide connectivity and allow the user to log in to a new device the first time without being on-premises. The Always On VPN device tunnel is easily deployed using a Microsoft Endpoint Manager configuration profile. Certificates required to support the device tunnel can be deployed with Microsoft Endpoint Manager and one of the certificate connectors for Microsoft Endpoint Manager.

Windows 10 Professional

If a Windows 10 Professional device is configured using Autopilot, and hybrid Azure AD joined is enabled, the Always On VPN device tunnel can still be provisioned, but it won’t start automatically because it requires Enterprise Edition to be fully functional. This prevents the user from being able to logon the first time. The device must be upgraded to Enterprise Edition before the first user logon. There are multiple ways to accomplish this depending on the deployment scenario and activation requirements.

Multiple Activation Key

The easiest way to upgrade Windows 10 Professional to Enterprise Edition is to obtain a Multiple Activation Key (MAK) and deploy that to clients using a Microsoft Endpoint Manager configuration profile. Follow the steps below to create a configuration profile to perform this upgrade.

  1. Open the Microsoft Endpoint Manager console and click on Devices > Configuration Profiles.
  2. Click Create profile.
  3. Select Windows 10 and later in the Platform drop-down list.
  4. Select Templates in the Profile type drop-down list.
  5. Select Edition upgrade and mode switch from the list of templates.
  6. Click Create.

Use the following steps to configure the settings for the configuration profile.

  1. Enter a descriptive name for the configuration profile in the Name field.
  2. Enter a description for the profile in the Description field (optional).
  3. Click Next.
  4. Expand the Edition Upgrade section and select Windows 10 Enterprise from the Edition to upgrade to drop-down list.
  5. Enter your multiple activation product key in the Product Key field.

    Always On VPN and Autopilot Hybrid Azure AD Join

Once complete, assign the configuration profile to the appropriate groups and click Create.

KMS Activation

If Key Management Service (KMS) activation is required, follow the steps listed previously for MAK. Enter the KMS client setup key for Windows 10 Enterprise which is NPPR9-FWDCX-D2C8J-H872K-2YT43. The device will complete KMS activation when it can connect to the on-premises KMS host.

Subscription Activation

Windows 10 Enterprise Edition licensing is included in some Microsoft 365 subscriptions. This poses a unique challenge for hybrid Azure AD join scenarios, however. Specifically, subscription activation is a “step-up” process that requires Windows 10 Professional to have been successfully activated previously. Also, this occurs after the user logs on, but the user cannot log on unless the device tunnel is active. Catch 22!

Workaround

A multi-step process is required to address the limitations imposed by subscription activation. To begin, the device must be upgraded to Enterprise Edition, so the device tunnel is available for the initial user logon. This is a temporary, one-time upgrade to Enterprise Edition solely for the purpose of getting the device tunnel to connect and allow the user to authenticate.

To begin, download this PowerShell script and follow the steps below to deploy it to Windows 10 devices using Microsoft Endpoint Manager.

  1. Open the Microsoft Endpoint Manager console and click on Devices > Scripts.
  2. Click Add and select Windows 10.
  3. Enter a descriptive name for the configuration profile in the Name field.
  4. Enter a description for the profile in the Description field (optional).
  5. Click Next.
  6. Enter the location of the PowerShell script in the Script location field.
  7. Click Next, then assign the script to the appropriate device group(s) and click Add.

The PowerShell script will automatically install the KMS client setup key for Windows 10 Enterprise Edition, then restart the network interfaces to ensure the device tunnel starts. This will immediately upgrade the client device to Windows 10 Enterprise Edition and allow the user to authenticate.

Subscription activation with a step-up upgrade to Enterprise Edition still requires that Windows 10 Professional be activated first. To accomplish this, the embedded Windows 10 Professional key must be re-installed on the client. To do this, download this PowerShell script and follow the same steps listed previously to deploy a PowerShell script with Microsoft Endpoint Manager. However, this script should be assigned to users, not devices.

Once this script is run on the client it will be downgraded (temporarily) to Windows 10 Professional edition. After activation is successful, subscription activation will once again upgrade the client to Windows 10 Enterprise Edition.

Considerations

As you can see, the process of getting a Windows 10 Professional edition client onboarded in a hybrid Azure AD joined scenario is somewhat complex. My advice is to avoid this scenario whenever possible. Access to on-premises resources with the Always On VPN user tunnel with full single sign-on support is still available for users on Windows 10 devices that are Azure AD joined only. Unless there is a specific requirement to manage client devices using on-premises Active Directory and group policy, consider choosing native Azure AD join with Autopilot and manage devices using Microsoft Endpoint Manager exclusively.

Special Thanks

I would like to extend a special thank you to everyone in the Microsoft Endpoint Manager community who provided valuable input and feedback for me on this topic, especially John Marcum, Michael Niehaus, and Sandy Zeng. Follow the #MEMCM hashtag on Twitter to keep up on all things Microsoft Endpoint Manager.

Additional Information

Overview of Windows Autopilot

Windows 10 Subscription Activation

Windows 10 Always On VPN Class-Based Default Route and Microsoft Endpoint Manager

Windows 10 Always On VPN Device Tunnel and Custom Cryptography in Microsoft Endpoint Manager

Always On VPN Class-Based Default Route and Intune

`Always On VPN Class-Based Default Route and IntuneIn a recent post, I described how to configure routing for Windows 10 Always On VPN clients. In that article, I shared guidance for disabling the class-based default route in favor of defining specific routes for the VPN client. While this is easy enough to do when you use custom XML (deployed via PowerShell, SCCM, or Intune), there is a known limitation when using the native Intune UI that could present some challenges.

Intune VPN Profile Configuration

Defining specific routes is easy to do in Intune using the native VPN configuration profile. In the Configuration settings expand Split Tunneling and click Enable. The administrator can then add routes by entering their Destination prefix and Prefix size, as shown here.

Always On VPN Class-Based Default Route and Intune

Class-Based Default Route

The limitation with using Intune to configure routes is that there is currently no option to disable the class-based default route as there is with custom XML. This means the routes shown in the example above will be added to the client, but the class-based route will also be added automatically, as shown here (class-based default route highlighted with the arrow).

Always On VPN Class-Based Default Route and Intune

Considerations

In most cases, the inclusion of the class-based default route along with the administrator-defined routes will not be a problem. However, in some scenarios, it could yield unexpected results. Specifically, Always On VPN clients may have unintended access to some networks over the VPN tunnel. This is most significant for the Always On VPN device tunnel, where it is common to limit access to only specific resources using individual host routes.

Workaround

Today there is no option to disable the class-based default route using the native Intune UI. Your only option is to deploy the Always On VPN profile using custom XML, as described here.

Additional Information

Deploying Windows 10 Always On VPN with Intune and Custom XML

Deploying Windows 10 Always On VPN Device Tunnel with Intune and Custom XML

Windows 10 Always On VPN Routing Configuration

Windows 10 Always On VPN Device Tunnel Operation and Best Practices

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