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All posts tagged EKU

Always On VPN Error 13806

Troubleshooting Always On VPN Error 691 and 812 – Part 2

As a follow-up to my last post regarding Always On VPN error 13801, this post will cover a similar and related error administrators may encounter, the 13806 error. As mentioned previously, certificate configuration is crucial for Always On VPN deployments. I described some specific certificates requirements for IKEv2 in this earlier post. Following this guidance, administrators should have no issues with IKEv2 Always On VPN connections. However, it is always possible to encounter an error if any of these certificates are missing or misconfigured.

Error 13806

Much like the error 13801 described previously, 13806 is also common. When an Always On VPN connection using IKEv2 fails, the Windows Application event log will record an event ID 20227 from the RasClient source. The error message states the following:

“The user [username] dialed a connection named [connection name] which has failed. The error code returned on failure is 13806”.

IKE Failed To Find Valid Machine Certificate

Error 13806 translates to ERROR_IPSEC_IKE_NO_CERT, indicating IKE failed to find a valid machine certificate. The problem can be on the device, the VPN server, or an issue with the VPN server configuration.

Device Certificate

For the device tunnel, the most obvious cause of this error is a missing device authentication certificate on the client itself. Ensure the endpoint has a valid certificate issued by the organization’s internal PKI that includes Client Authentication EKU (OID 1.3.6.1.5.5.7.3.2). The certificate must have a subject name matching the device’s FQDN. It must also be valid (not expired), trusted, and not revoked.

Certificate Chain

A 13806 error will occur if the device certificate installed on the client is not trusted or if the client does not trust the certificate installed on the VPN server. Ensure the client has all the necessary root and intermediate certification authority (CA) certificates installed in their respective certificate stores.

VPN Server Certificate

A 13806 error can also occur if the VPN server does not have a properly configured server certificate. Ensure the VPN server has a valid certificate issued by the organization’s internal PKI that includes both the Server Authentication (OID 1.3.6.1.5.5.7.3.1) and IP security IKE intermediate (OID 1.3.6.1.5.5.8.2.2) EKUs. The subject name must match the public fully qualified domain name (FQDN) used by VPN clients to connect to the VPN server (not the server’s NetBIOS name). Again, ensure the certificate is valid (not expired), trusted, not revoked, and all necessary root and intermediate CA certificates are installed in their respective certificate stores.

Certificate Revocation

An expired Certificate Revocation List (CRL) can also result in a 13806 error. Open the Enterprise PKI console (pkiview.msc) on an issuing CA and review the status of all CRLs. If any are expired, resolve any issues preventing the CRL from publishing successfully, then issue a new CRL by running certutil.exe -crl on the issuing CA server.

RRAS Configuration

Another cause of the 13806 error for the user tunnel is a misconfigured Routing and Remote Access Service (RRAS) VPN server. An error 13806 can happen if the administrator incorrectly defines a trusted root CA using Set-VpnAuthProtocol. Ensure that the root certificate thumbprint matches exactly the root CA server’s thumbprint used to issue certificates to VPN devices and the VPN server.

Get-VpnAuthProtocol

Root CA Certificate Thumbprint

Resolution

Ensure that devices and VPN servers have correctly configured certificates installed. If the root CA certificate is assigned incorrectly on the VPN server, follow the guidelines detailed here to update the configuration.

Additional Information

Microsoft Windows Always On VPN Error 13801

Microsoft Windows Always On VPN Certificate Requirements for IKEv2

Microsoft Windows Always On VPN IPsec Root Certificate Configuration Issue

Microsoft Windows Always On VPN IKEv2 Policy Mismatch Error

Microsoft Windows Always On VPN IKEv2 Security Configuration

Microsoft Windows Always On VPN IKEv2 Fragmentation

Microsoft Windows Always On VPN IKEv2 Load Balancing and NAT

Microsoft Windows Always On VPN IKEv2 Features and Limitations

16 Comments

by Richard M. Hicks on December 20, 2021 • Permalink

Posted in Always On VPN, PKI, PowerShell, Windows Server

Tagged Always On VPN, certificates, device tunnel, EKU, Event ID 20227, IKEv2, IPsec, OID, PKI, RasClient, Remote Access, RRAS, VPN, Windows 10, Windows 11

Posted by Richard M. Hicks on December 20, 2021

https://directaccess.richardhicks.com/2021/12/20/always-on-vpn-error-13806/

Always On VPN Error 13801

Certificate configuration is crucial for Always On VPN deployments. I described some specific certificates requirements for IKEv2 in this previous post. Following this guidance, administrators should have no issues with IKEv2 Always On VPN connections. However, it is always possible to encounter an error if any of these certificates are missing or misconfigured.

Error 13801

One of the most common errors related to IKEv2 and certificates is 13801. When an Always On VPN connection using IKEv2 fails, the Windows Application event log will record an event ID 20227 from the RasClient source. The error message states the following:

“The user [username] dialed a connection named [connection name] which has failed. The error code returned on failure is 13801”.

IKE Authentication Credentials are Unacceptable

Error 13801 translates to ERROR_IPSEC_IKE_AUTH_FAIL, indicating an authentication failure related to IPsec. The problem can be on the device, the VPN server, or an issue with the VPN server configuration.

Authentication Methods

To begin, ensure that the appropriate authentication method is enabled on the Routing and Remote Access (RRAS) server. Right-click the VPN server in the RRAS management console (rrasmgmt.msc) and choose Properties. Next, click on the Security tab and then click on the Authentication Methods button.

Select the ‘Extensible authentication protocol (EAP)’ to support IKEv2 user tunnel connections. In addition, select ‘Allow machine certificate authentication for IKEv2’ to support Always On VPN device tunnel connections.

Certificate Chain

A 13801 error will occur if the client does not trust the certificate installed on the VPN server. Ensure the client has all the necessary root and intermediate certification authority (CA) certificates installed in their respective certificate stores.

VPN Server Certificate

A 13801 error can also occur if the VPN server does not have a properly configured server certificate. Ensure the VPN server has a valid certificate issued by the organization’s internal PKI that includes both the Server Authentication (OID 1.3.6.1.5.5.7.3.1) and IP security IKE intermediate (OID 1.3.6.1.5.5.8.2.2) EKUs. The subject name must match the public fully qualified domain name (FQDN) used by VPN clients to connect to the VPN server (not the server’s NetBIOS name). Again, ensure the certificate is valid (not expired), trusted, not revoked, and all necessary root and intermediate CA certificates are installed in their respective certificate stores.

Certificate Revocation

An expired Certificate Revocation List (CRL) can also result in a 13801 error. Open the Enterprise PKI console (pkiview.msc) on an issuing CA and review the status of all CRLs. If any are expired, resolve any issues preventing the CRL from publishing successfully, then issue a new CRL by running certutil.exe -crl on the issuing CA server.

RRAS Configuration

Another cause of the 13801 error for the device tunnel is a misconfigured Routing and Remote Access Service (RRAS) VPN server. An error 13801 can happen if the administrator incorrectly defines a trusted root CA using Set-VpnAuthProtocol. Ensure that the root certificate thumbprint matches exactly the root CA server’s thumbprint used to issue certificates to VPN devices and the VPN server.

Get-VpnAuthProtocol

Root CA Certificate Thumbprint

Resolution

Additional Information

Microsoft Windows Always On VPN Error 13806

Microsoft Windows Always On VPN Certificate Requirements for IKEv2

Microsoft Windows Always On VPN IPsec Root Certificate Configuration Issue

Microsoft Windows Always On VPN IKEv2 Policy Mismatch Error

Microsoft Windows Always On VPN IKEv2 Security Configuration

Microsoft Windows Always On VPN IKEv2 Fragmentation

Microsoft Windows Always On VPN IKEv2 Load Balancing and NAT

Microsoft Windows Always On VPN IKEv2 Features and Limitations

23 Comments

by Richard M. Hicks on December 13, 2021 • Permalink

Posted in Always On VPN, Authentication and MFA, PKI, PowerShell, Windows Server

Tagged Always On VPN, authentication, certificates, device tunnel, EKU, Event ID 20227, IKEv2, IPsec, OID, PKI, RasClient, RRAS, user tunnel, VPN, Windows 10, Windows 11

Posted by Richard M. Hicks on December 13, 2021

https://directaccess.richardhicks.com/2021/12/13/always-on-vpn-error-13801/

Always On VPN Users Prompted for Certificate

Always On VPN Users Prompted for Certificate When deploying Windows 10 Always On VPN using Protected Extensible Authentication Protocol (PEAP) authentication with client certificates, administrators may find the VPN connection does not establish automatically. In this specific scenario the client is prompted to select a certificate to use to authenticate to the VPN server.

Always On VPN Users Prompted for Certificate

Multiple Certificates

This can occur when certificates from multiple Certification Authorities (CAs) are issued to the user that include the Client Authentication Enhanced Key Usage (EKU). When this happens, the user is forced to select the correct certificate to use for VPN authentication.

Clearly this is less than ideal, as it not only breaks the seamless and transparent nature of Always On VPN, the user may select the wrong certificate resulting in authentication failure. Ideally the client should be configured to select the correct certificate without user interaction.

Certificate Selection

Follow the steps below to configure automatic certificate selection for VPN authentication.

On a VPN client, right-click the Always On VPN connection and choose Properties.
Select the Security tab.
In the Authentication section click Properties below Use Extensible Authentication Protocol (EAP).
In the Select Authentication Method section click Configure.
In the When connecting section click Advanced.
Check the box next to Certificate Issuer.
Select the root CA used to issue client authentication certificates for VPN authentication.
Click Ok four times to save the configuration.

Always On VPN Users Prompted for Certificate

Once complete, export the EAP configuration to XML from the VPN client and paste the new settings in Intune or in your custom ProfileXML.

Certificate Purpose

By default, a client certificate requires only the Client Authentication EKU to establish a VPN connection. In some cases, this may not be desirable. For example, consider a deployment where Client Authentication certificates are issued to all users for Wi-Fi authentication. Depending on the Network Policy Server (NPS) configuration, these certificates may also be used to authenticate to the VPN.

VPN Specific Certificate

Follow the steps below to create a user authentication certificate template to be used exclusively for VPN authentication.

Certificate Template

On the CA server, open the Certificate Templates management console (certtmpl.msc).
Right-click the certificate template configured for VPN authentication and choose Properties.
Select the Extension tab.
Highlight Application Policies and click Edit.
Click Add.
Click New.
Enter a descriptive name for the new application policy.
Copy the Object identifier for later use and click Ok four times to save the configuration.
If certificate autoenrollment is configured and the certificate is already provisioned to users, right-click the certificate template and choose Reenroll All Certificate holders.

Client Configuration

On the VPN client, follow the steps outlined previously to configure certificate selection.
In addition to choosing a certificate issuer, select Extended Key Usage (EKU).
Uncheck All Purpose.
Select Client Authentication and the following EKUs.
Click Add.
Click Add once more.
Enter the name of the custom EKU policy created previously.
Enter the custom EKU object identifier copied previously from the custom policy.
Click Ok twice.
Uncheck AnyPurpose and the following EKUs.
Click Ok four times to save the configuration.

Always On VPN Users Prompted for Certificate

Once complete, export the EAP configuration to XML from the VPN client and paste the new settings in Intune or in your custom ProfileXML.

Additional Information

Windows 10 Always On VPN Clients Prompted for Authentication when Accessing Internal Resources

Get-EapConfiguration PowerShell Script on GitHub

Windows 10 Always On VPN Hands-On Training

25 Comments

by Richard M. Hicks on May 28, 2019 • Permalink

Posted in Always On VPN, Authentication and MFA, PKI, PowerShell, Windows Server

Tagged Always On VPN, authentication, certificates, Certification Authority, EAP, EKU, PEAP, PKI, VPN, Windows 10

Posted by Richard M. Hicks on May 28, 2019

https://directaccess.richardhicks.com/2019/05/28/always-on-vpn-users-prompted-for-certificate/

Always On VPN Clients Prompted for Authentication when Accessing Internal Resources

Always On VPN Clients Prompted for Authentication when Accessing Internal Resources When deploying Windows 10 Always On VPN using Protected Extensible Authentication Protocol (PEAP) with client authentication certificates, the administrator may encounter a scenario in which the user can establish a VPN connection without issue, but when accessing internal resources they are prompted for credentials and receive the following error message.

“The system cannot contact a domain controller to service the authentication request. Please try again later.”

Always On VPN Clients Prompted for Authentication when Accessing Internal Resources

Resolution

This can occur if one or more domain controllers in the enterprise have expired or missing domain controller authentication certificates. To ensure seamless single sign-on to internal resources, ensure that all domain controllers have a certificate issued by the internal certification authority (CA) that includes the Server Authentication (1.3.6.1.5.5.7.3.1), Client Authentication (1.3.6.1.5.5.7.3.2), KDC Authentication (1.3.6.1.5.2.3.5), and Smart Card Logon (1.3.6.1.4.1.311.20.2.2) Enhanced Key Usage (EKU). Administrators can duplicate the Kerberos Authentication template for this purpose.

Always On VPN Clients Prompted for Authentication when Accessing Internal Resources

Additional Information

Windows 10 Always On VPN Certificate Requirements for IKEv2

Windows 10 Always On VPN Hands-On Training

28 Comments

by Richard M. Hicks on May 20, 2019 • Permalink

Posted in Always On VPN, Authentication and MFA, Cryptography, PKI, Windows Server

Tagged Always On VPN, authentication, certificates, Certification Authority, domain controller, EAP, EKU, PEAP, PKI, Remote Access, smart card, VPN, Windows 10

Posted by Richard M. Hicks on May 20, 2019

https://directaccess.richardhicks.com/2019/05/20/always-on-vpn-clients-prompted-for-authentication-when-accessing-internal-resources/

Always On VPN SSL Certificate Requirements for SSTP

The Windows Server 2016 Routing and Remote Access Service (RRAS) is commonly deployed as a VPN server for Windows 10 Always On VPN deployments. Using RRAS, Always On VPN administrators can take advantage of Microsoft’s proprietary Secure Socket Tunneling Protocol (SSTP) VPN protocol. SSTP is a Transport Layer Security (TLS) based VPN protocol that uses HTTPS over the standard TCP port 443 to encapsulate and encrypt communication between the Always On VPN client and the RRAS VPN server. SSTP is a firewall-friendly protocol that ensures ubiquitous remote network connectivity. Although IKEv2 is the protocol of choice when the highest level of security is required for VPN connections, SSTP can still provide very good security when implementation best practices are followed.

SSTP Certificate

Since SSTP uses HTTPS for transport, a common SSL certificate must be installed in the Local Computer/Personal/Certificates store on the RRAS VPN server. The certificate must include the Server Authentication Enhanced Key Usage (EKU) at a minimum. Often SSL certificates include both the Server Authentication and Client Authentication EKUs, but the Client Authentication EKU is not strictly required. The subject name on the certificate, or at least one of the Subject Alternative Name entries, must match the public hostname used by VPN clients to connect to the VPN server. Multi-SAN (sometimes referred to as UC certificates) and wildcard certificates are supported.

Always On VPN Certificate Requirements for SSTP

Certification Authority

It is recommended that the SSL certificate used for SSTP be issued by a public Certification Authority (CA). Public CAs typically have their Certificate Revocation Lists (CRLs) hosted on robust, highly available infrastructure. This reduces the chance of failed VPN connection attempts caused by the CRL being offline or unreachable.

Using an SSL certificate issued by an internal, private CA is supported if the CRL for the internal PKI is publicly available.

Key Type

RSA is the most common key type used for SSL certificates. However, Elliptic Curve Cryptography (ECC) keys offer better security and performance, so it is recommended that the SSTP SSL certificate be created using an ECC key instead.

Always On VPN Certificate Requirements for SSTP

To use an ECC key, be sure to specify the use of a Cryptographic Next Generation (CNG) key and select the ECDSA_P256 Microsoft Software Key Storage Provider (CSP) (or greater) when creating the Certificate Signing Request (CSR) for the SSTP SSL certificate.

Always On VPN Certificate Requirements for SSTP

Most public CAs will support certificate signing using ECC and Elliptic Curve Digital Signature Algorithm (ECDSA). If yours does not, find a better CA. 😉

Forward Secrecy

Forward secrecy (sometimes referred to as perfect forward secrecy, or PFS) ensures that session keys can’t be compromised even if the server’s private key is compromised. Using forward secrecy for SSTP is crucial to ensuring the highest levels of security for VPN connections.

To enforce the use of forward secrecy, the TLS configuration on the VPN server should be prioritized to prefer cipher suites with Elliptic Curve Diffie-Hellman Ephemeral (ECDHE) key exchange.

Authenticated Encryption

Authenticated encryption (AE) and authenticated encryption with associated data (AEAD) is a form of encryption that provides better data protection and integrity compared to older block or stream ciphers such as CBC or RC4.

To enforce the use of authenticated encryption, the TLS configuration on the VPN server should be prioritized to prefer cipher suites that support Galois/Counter Mode (GCM) block ciphers.

Important Note: In Windows Server 2016, GCM ciphers can be used with both RSA and ECC certificates. However, in Windows Server 2012 R2 GCM ciphers can only be used when an ECC certificate is used.

SSL Offload

Offloading SSL to a load balancer or application delivery controller (ADC) can be enabled to improve scalability and performance for SSTP VPN connections. I will cover SSL offload for SSTP in detail in a future post.

Summary

SSTP can provide good security for VPN connections when implementation and security best practices are followed. For optimum security, use an SSL certificate with an EC key and optimize the TLS configuration to use forward secrecy and authenticated cipher suites.

Additional Information

Always On VPN ECDSA SSL Certificate Request for SSTP

Always On VPN and Windows Server Routing and Remote Access Service (RRAS)

Always On VPN Protocol Recommendations for Windows Server RRAS

Always On VPN Certificate Requirements for IKEv2

3 Important Advantages of Always On VPN over DirectAccess

Microsoft SSTP Specification on MSDN

36 Comments

by Richard M. Hicks on July 16, 2018 • Permalink

Posted in Always On VPN, Cryptography, Load Balancing, PKI, TLS, Windows Server

Tagged certificates, Certification Authority, cryptography, EKU, encryption, IKEv2, PKI, Remote Access, RRAS, SSTP, TLS, TLS offload, Windows 10, Windows Server, Windows Server 2016

Posted by Richard M. Hicks on July 16, 2018

https://directaccess.richardhicks.com/2018/07/16/always-on-vpn-ssl-certificate-requirements-for-sstp/

Always On VPN Certificate Requirements for IKEv2

Always On VPN Certificate Requirements for IKEv2 Internet Key Exchange version 2 (IKEv2) is one of the VPN protocols supported for Windows 10 Always On VPN deployments. When the VPN server is Windows Server 2016 with the Routing and Remote Access Service (RRAS) role configured, a computer certificate must first be installed on the server to support IKEv2. There are some unique requirements for this certificate, specifically regarding the subject name and Enhanced Key Usage (EKU) configuration. In addition, some deployment scenarios may require a certificate to be provisioned to the client to support IKEv2 VPN connections.

Server Certificate

The IKEv2 certificate on the VPN server must be issued by the organization’s internal private certification authority (CA). It must be installed in the Local Computer/Personal certificate store on the VPN server. The subject name on the certificate must match the public hostname used by VPN clients to connect to the server, not the server’s hostname. For example, if the VPN server’s hostname is VPN1 and the public FQDN is vpn.example.net, the subject field of the certificate must include vpn.example.net, as shown here.