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Always On VPN and Intune Proactive Remediation

Always On VPN and Autopilot Hybrid Azure AD Join

When configuring and deploying Windows Always On VPN using Microsoft Endpoint Manager (MEM)/Intune, administrators may find that some settings are not exposed in the MEM UI. In some cases, deploying the configuration profile using custom XML is the workaround. However, many crucial Always On VPN settings are not exposed using either method. Here, administrators must resort to editing settings in the VPN configuration file on the client after provisioning the VPN profile.

Phonebook

A file called rasphone.pbk stores all Windows VPN settings on the endpoint. It includes name/value pairs that correspond to many settings administrators change manually in the GUI. Other settings can be changed using PowerShell. Depending on the connection type, the file can be found in one of two locations.

  • User Tunnel: $env:AppData\Microsoft\Network\Connections\Pbk\rasphone.pbk
  • Device Tunnel: $env:ProgramData\Microsoft\Network\Connections\Pbk\rasphone.pbk

Documentation for Windows VPN client phonebook entry settings can be found here.

Limitations

Unfortunately, editing the rasphone.pbk file isn’t always convenient. Making the changes is technically easy. Administrators can write a simple PowerShell script to update the text file as required. However, automating this at scale is challenging. Thankfully, Intune Proactive Remediations can help.

Proactive Remediations

With Intune Proactive Remediations, administrators can create and deploy script packages to monitor and optionally update specific configuration settings. The package includes two scripts, a detection script, and a remediation script. The detection script looks at the current value of a particular setting and reports on its compliance. The remediation script is triggered to update the setting if the value is incorrect.

Requirements

Intune Proactive Remediations has some specific licensing requirements. Administrators must also enroll devices into Endpoint analytics and provision a Windows Health Monitoring configuration profile. There are also limitations on the size and type of scripts that administrators can use. More information on prerequisites can be found here.

Script Packages

Administrators can create detection and remediation PowerShell scripts to update settings in rasphone.pbk, or optionally, they can download sample scripts from my GitHub repository here. This repository contains user and device tunnel detection and remediation scripts for many popular settings in rasphone.pbk. Examples include updating the VPN Strategy, changing VPN interface metrics, disabling class-based default routes, and many more.

Note: The scripts in my GitHub repository are examples only. While they can be used in production environments, they are basic and may not work as expected in all scenarios. For example, the scripts as written today assume only a single VPN profile provisioned. Unexpected results may occur if more than one VPN profile exists. Please use them at your own risk.

Deployment

In this example, we’ll deploy a Proactive Remediation to disable IKE mobility for user tunnel VPN connections. To configure an Intune Proactive Remediation, open the Microsoft Endpoint Manager portal (https://intune.microsoft.com/) and navigate to Devices > Remediations. After creating or downloading the detection and remediation scripts, perform the following steps to create and deploy a Proactive Remediation script package.

  1. Click Create script package.
  2. Enter a name for the package in the Name field.
  3. Enter a description for the package in the Description field (optional).
  4. Click Next.
  5. Click the blue folder icon next to the Detection script file field and upload the detection script.
  6. Click the blue folder icon next to the Remediation script file field and upload the associated remediation script.
  7. For user tunnel connections, click Yes next to Run this script using the logged-on credentials. For device tunnel connections, click No.
  8. Click Next.
  9. Define scope tags as required.
  10. Click Next.
  11. Assign a group and choose a schedule. The detection script can be run once, daily, hourly, or on an hourly interval.
  12. Click Next, then click Create.

Click Refresh to update the UI to display the newly created script package.

Caveats

Be advised that timing issues could lead to delays in functionality. For example, if there’s a change to an Always On VPN profile after a Proactive Remediation detection script runs, the changes will not be detected until the detection script runs again. Also, changes made while the VPN is active will not take effect until after restarting the connection.

Special Thanks

Special thanks to Tom Klaver at Inspark for turning me on to this feature. It has been an absolute lifesaver for sure!

Additional Information

Microsoft Intune Proactive Remediation Tutorial

Windows VPN Phonebook Entry Settings

Intune Proactive Remediation Script Samples on GitHub

Microsoft Windows Always On VPN Class-Based Default Route and Intune

Microsoft Windows Always On VPN Short Name Access Failure

9 Comments
by Richard M. Hicks on December 6, 2021  •  Permalink
Posted in administration, Always On VPN, AOVPN, Azure, Azure AD, Azure VPN, Azure VPN Gateway, cloud, Endpoint Manager, Enterprise, enterprise mobility, GitHub, Intune, MEM, MEMCM, Microsoft Endpoint Manager, Microsoft Intune, Mobility, Operational Support, PowerShell, public cloud, Remote Access, SCCM, System Center Configuration Manager, systems management, troubleshooting, user tunnel, VPN, Windows 10, Windows 11
Tagged , , , , , , , , , , , , , , , , , , , ,

Posted by Richard M. Hicks on December 6, 2021

https://directaccess.richardhicks.com/2021/12/06/always-on-vpn-and-intune-proactive-remediation/

Always On VPN Client Routes Missing

Choosing an Enterprise VPN

When configuring Always On VPN for Windows 10 and Windows 11 clients, administrators may encounter a scenario where an IPv4 route defined in Microsoft Endpoint Manager/Intune or custom XML is not reachable over an established Always On VPN connection. Further investigation indicates the route is added to the configuration on the endpoint but does not appear in the routing table when the connection is active.

Routing Configuration

When split tunneling is enabled, administrators must define routes to IP networks that are reachable over the Always On VPN connection. The method of defining these routes depends on the client configuration deployment method.

Endpoint Manager

Using Microsoft Endpoint Manager, administrators define IP routes in the Split Tunneling section of the configuration settings for the Always On VPN device configuration profile. Routes are defined by entering the destination prefix and prefix size. In this example, the 10.0.0.0/8 and 172.21.12.0/21 IPv4 networks are defined for routing over the Always On VPN tunnel.

Custom XML

Using custom XML deployed using Microsoft Endpoint Manager, System Center Configuration Manager (SCCM), or PowerShell, routes are defined in the XML file using the following syntax.

Client Configuration

Validate the routing configuration has been implemented on the endpoint successfully by running the following PowerShell command.

Get-VpnConnection -Name <Connection Name> | Select-Object -ExpandProperty Routes

As you can see here, the IPv4 routes 10.0.0.0/8 and 172.21.12.0/21 are included in the client’s Always On VPN configuration, as shown below.

Missing Route

However, after establishing an Always On VPN connection, the 172.21.12.0/21 network is not reachable. To continue troubleshooting, run the following PowerShell command to view the active routing table.

Get-NetRoute -AddressFamily IPv4

As you can see above, the only IPv4 route in the VPN configuration added to the routing table is the 10.0.0.0/8 network. The 172.21.12.0/21 IPv4 route is missing.

Network Prefix Definition

IPv4 routes missing from the Always On VPN client’s routing table result from incorrect network prefix definition. Specifically, the IPv4 route 172.21.12.0/21 used in the example here is not a valid network address. Rather, it is a host address in the 172.21.8.0/21 network, as shown below.

The Get-Subnet PowerShell cmdlet is part of the Subnet PowerShell module. To install this module, run the following PowerShell command.

Install-Module Subnet

Resolution

Using the example above, enabling access to the 172.21.12.0/21 subnet would require defining the IPv4 prefix in the routing configuration as 172.21.8.0/21. The moral of this story is always validate routing prefixes to ensure they are, in fact, network addresses and not host addresses.

Additional Information

Always On VPN Routing Configuration

Always On VPN Default Class-based Route and Microsoft Endpoint Manager/Intune

19 Comments
by Richard M. Hicks on November 8, 2021  •  Permalink
Posted in Always On VPN, AOVPN, Azure VPN, Azure VPN Gateway, Enterprise, enterprise mobility, Intune, MEM, MEMCM, Microsoft Endpoint Manager, Microsoft Intune, Mobility, Operational Support, PowerShell, ProfileXML, Remote Access, routing, split tunnel, split tunneling, troubleshooting, user tunnel, VPN, Windows 10, Windows 11
Tagged , , , , , , , , , , , , , , , , , , , , ,

Posted by Richard M. Hicks on November 8, 2021

https://directaccess.richardhicks.com/2021/11/08/always-on-vpn-client-routes-missing/

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

3 Comments
by Richard M. Hicks on October 4, 2021  •  Permalink
Posted in Always On VPN, AOVPN, authentication, certificates, DNS, ECC, Elliptic Curve Cryptography, Encryption, Enterprise, enterprise mobility, Mobility, Operational Support, PKI, PowerShell, public key infrastructure, Remote Access, routing and remote access service, RRAS, Secure Socket Tunneling Protocol, Security, SSL, SSL and TLS, SSTP, TLS, user tunnel, VPN, Windows 10, Windows 11, Windows Server 2016, Windows Server 2019, Windows Server 2022

Posted by Richard M. Hicks on October 4, 2021

https://directaccess.richardhicks.com/2021/10/04/always-on-vpn-sstp-with-lets-encrypt-certificates/

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