All posts in category network policy server

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
5 Comments
by Richard M. Hicks on September 27, 2021  •  Permalink
Posted in Always On VPN, Always On VPN Book, AOVPN, AOVPN Book, authentication, Azure, Azure Active Directory, Azure AD, Azure Conditional Access, Azure MFA, Azure Virtual WAN, Azure VPN, Azure VPN Gateway, certificates, cloud, Conditional Access, Device Management, device tunnel, education, Endpoint Manager, Enterprise, enterprise mobility, High Availability, InTune, Intune Certificate Connector, Intune PFX Connector, learning, Load Balancing, MFA, Microsoft Endpoint Manager, Microsoft Intune, Mobility, Multifactor Authentiction, NDES, Network Device Enrollment Services, network policy server, NPS, Operational Support, PFX Connector, PKI, PowerShell, ProfileXML, public cloud, public key infrastructure, Recommended Reading, Remote Access, reporting, routing and remote access service, RRAS, SCCM, SCEP, Security, Simple Certificate Enrollment Protocol, System Center Configuration Manager, systems management, Traffic Filter, user tunnel, VPN, Windows 10, Windows 11, Windows Server 2012 R2, Windows Server 2016, Windows Server 2019, Windows Server 2022, Zero Trust, Zero Trust Network Access, ZTNA
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Posted by Richard M. Hicks on September 27, 2021

https://directaccess.richardhicks.com/2021/09/27/always-on-vpn-book-available-for-pre-order/

Always On VPN Error 853 on Windows 11

Recently I did some validation testing with Always On VPN on Windows 11, and I’m happy to report that everything seems to work without issue. However, a few readers have reported 853 errors when establishing an Always On VPN connection after upgrading to Windows 11.

Can’t Connect

After upgrading to Windows 11, an Always On VPN connection may fail with the following error message.

“The remote access connection completed, but authentication failed because the certificate that authenticates the client to the server is not valid. Ensure the certificate used for authentication is valid.”

Error 853

In addition, the Application event log records an event ID 20227 from the RasClient source that includes the following message.

“The user <username> dialed a connection name <connection name> which has failed. The error code returned on failure is 853.”

Server Identity

This error will occur when using Protected Extensible Authentication Protocol (PEAP) authentication. Specifically, it can happen when the option to verify NPS server validity by its certificate is selected, and an explicit list of NPS servers is defined, as shown here.

Case Sensitive

In this specific scenario, Windows 11 now appears to be case-sensitive when it compares the NPS server name entered in the NPS configuration to the Subject Name on the certificate returned by the server. For example, if the Subject Name (or Subject Alternative Name, if present) entry on the NPS server certificate is nps.lab.richardhicks.net, using NPS.lab.richardhicks.net will not match and return an 853 error.

Windows 11

Case matching when validating the NPS server certificate is a change in behavior from Windows 10. Before Windows 11, this comparison was case-insensitive, and any combination of case would match if the entire hostname matched. Going forward, it appears Microsoft has also decided to require case matching to validate the server certificate.

Recommendations

Administrators should look carefully at the server certificate issued to the NPS server and ensure their client configuration accurately reflects the hostname in a case-sensitive manner to ensure a smooth migration from Windows 10 to Windows 11.

Additional Information

Troubleshooting Windows 10 Always On VPN Error 853

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

22 Comments
by Richard M. Hicks on September 23, 2021  •  Permalink
Posted in Always On VPN, AOVPN, authentication, certificates, EAP, Enterprise, enterprise mobility, extensible authentication protocol, Mobility, Name Resolution, network policy server, NPS, PEAP, Protected EAP, Remote Access, Security, troubleshooting, VPN, Windows 11
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Posted by Richard M. Hicks on September 23, 2021

https://directaccess.richardhicks.com/2021/09/23/always-on-vpn-error-853-on-windows-11/

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

24 Comments
by Richard M. Hicks on August 29, 2021  •  Permalink
Posted in Always On VPN, AOVPN, Azure, Azure Active Directory, Azure AD, Azure Conditional Access, Azure MFA, Azure VPN, Azure VPN Gateway, certificates, Conditional Access, EAP, Enterprise, enterprise mobility, HAADJ, Hybrid Azure AD Join, MFA, Mobility, Multifactor Authentiction, network policy server, NPS, Operational Support, PowerShell, Protected EAP, Remote Access, RRAS, user tunnel, VPN, Windows 10
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Posted by Richard M. Hicks on August 29, 2021

https://directaccess.richardhicks.com/2021/08/29/always-on-vpn-authentication-failure-with-azure-conditional-access/

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