Always On VPN Windows Server 2025 Binding Handle is Invalid Error

Microsoft released Windows Server 2025 late last year. I’ve been doing extensive testing with the Routing and Remote Access (RRAS) role, commonly deployed to support Always On VPN client connections. I heavily use automation to deploy VPN servers in my lab and for large customer deployments, and after deploying some new Windows Server 2025 machines, I encountered the “binding handle is invalid” error message when running specific commands.

VPN Ports

By default, Windows Server RRAS enables IKEv2 for Remote Access (RAS) and SSTP for RAS and Routing. Each is provisioned with 128 ports. Often, these settings are updated because there are not enough ports to support expected concurrent connections. Also, SSTP should not be enabled for Routing as it is not required, and PPPoE is enabled for Routing, which is also not required. The best practice is to disable any protocols and services that are not being used.

Although updating these settings can be updated in the GUI (rrasmgmt.msc), automating these changes requires command line configuration.

Netsh

Here’s the command to configure additional SSTP ports and disable Routing using netsh.exe.

netsh.exe ras set wanports device = “WAN Miniport (SSTP)” rasinonly = enabled ddinout = disabled ddoutonly = disabled maxports = 500

However, running this command returns the following error message.

“The binding handle is invalid.”

PowerShell

You might be wondering why we don’t use PowerShell for these tasks. Sadly, not all these settings are exposed via PowerShell. For example, with the native Set-VpnServerConfiguration PowerShell command, you can set the number of ports for IKEv2, SSTP, L2TP, and GRE. However, you cannot turn these protocols on or off entirely as you can with netsh.exe commands.

Here’s an example of setting up VPN server port configuration using PowerShell.

Set-VpnServerConfiguration -SstpPorts 500 -Ikev2Ports 500 -PassThru

Note: You must restart the server (not just the RemoteAccess service) when increasing the number of ports beyond the default setting of 128.

Set-VpnServerConfiguration does not support configuration for PPTP. However, PPTP is disabled by default on Windows Server 2025.

Backup and Restore

This issue will also impede the ability to back and restore the RRAS configuration using netsh.exe. You can back up the RRAS configuration by running the following command.

netsh.exe ras dump | Out-File rasconfig.txt -Encoding ascii

You can restore the configuration by running the following command.

netsh.exe exec .\rasconfig.txt

However, you will receive “binding handle is invalid” error when running this command.

AovpnTools

Be advised that the following functions in my AovpnTools PowerShell module use netsh.exe commands that will return the “binding handle is invalid” error message when configuring Windows Server 2025 servers.

Workaround

Until Microsoft resolves this issue, administrators must use a combination of the native PowerShell commands and manual configuration using the Routing and Remote Access management console (rrasmgmt.msc) to implement these settings changes. When backing up and restoring the RRAS configuration, additional configuration will be required after configuration import to ensure the VPN server port configuration is configured correctly.

Additional Information

Always On VPN PowerShell Module on GitHub

November 2024 Microsoft Security Updates and DirectAccess

With the November 2024 security updates, Microsoft disclosed a vulnerability (CVE-2024-43639) in the Windows Server KDC Proxy service. This is a Remote Code Execution (RCE) vulnerability with a max severity rating of Critical. If you still use Microsoft DirectAccess for remote access, you’ll want to pay close attention to this bulletin.

KDC Proxy and DirectAccess

When DirectAccess is installed and configured, the KDC Proxy Service is enabled automatically and by default. By design, DirectAccess servers are exposed to the Internet, which significantly increases the risk of this vulnerability. Organizations that have deployed DirectAccess are encouraged to update their systems immediately.

Workaround

There is no known workaround available at this time. Apply the latest security updates to mitigate this risk.

Additional Information

Windows KDC Proxy Remote Code Execution Vulnerability

Microsoft DirectAccess Formally Deprecated

Microsoft Ignite 2024

The Microsoft Ignite conference will be held November 19-22, 2024, at the McCormick Place Conference Center in Chicago, IL. Ignite is the premier Microsoft event of the year and will be packed with many announcements about new products and technologies. Ignite is also a fantastic learning event with experts worldwide in attendance.

Meet Up

I’m excited to announce that Microsoft has invited me to participate in the event as part of their Expert Meet-Up program. I will spend time at the Windows Server station in the Azure Infrastructure section of the Hub. Below are the days and times I’ll be available.

  • Tuesday, November 19 – 3:30 PM to 7:30 PM CST
  • Wednesday, November 20 – 2:30 PM to 6:00 PM CST
  • Thursday, November 21 – 2:30 PM to 6:00 PM CST

Let’s Connect

Be sure to drop by and say hello! We can chat about Windows Server and Azure Infrastructure. Of course, we can also discuss all the technologies I usually work with, including Entra Private Access, Always On VPN, Intune and Cloud PKI, and certificates in general. I will also attend many social gatherings during the week, so look for me at those as well.

I look forward to seeing you at the event!

Additional Information

Microsoft Ignite 2024