DirectAccess IP-HTTPS Error 0x2af9

When troubleshooting DirectAccess client connectivity issues, you may encounter a scenario where clients are unable to connect using the IP-HTTPS IPv6 transition technology. Running ipconfig shows that the tunnel adapter IPHTTPSInterface media state is Media disconnected.

DirectAccess IP-HTTPS Error 0x2af9

Running the Get-NetIpHttpsState PowerShell command shows that the LastErrorCode is 0x2af9 (WSAHOST_NOT_FOUND) and the InterfaceStatus is Failed to connect to the IPHTTPS server; waiting to reconnect.

DirectAccess IP-HTTPS Error 0x2af9

The 0x2af9 error differs slightly from the more common 0x274c IP-HTTPS connection time out error (WSAETIMEDOUT). In this scenario the DirectAccess client can successfully resolve the DirectAccess public hostname to an IPv4 address, and if ICMP echo requests are allowed on the DirectAccess server’s public IPv4 address it will respond to ping.

DirectAccess IP-HTTPS Error 0x2af9

The DirectAccess client is also able to establish a TCP connection to the DirectAccess server using the Test-NetConnection PowerShell command.

DirectAccess IP-HTTPS Error 0x2af9

So, why is the IP-HTTPS interface unable to establish a transition tunnel connection when the DirectAccess server’s public hostname resolves correctly via DNS and the client can establish a TCP connection on port 443? Commonly this is caused by proxy server settings configured in the web browser on the DirectAccess client computer. Disabling the proxy server in the client’s web browser should restore DirectAccess client connectivity over IP-HTTPS.

DirectAccess IP-HTTPS Error 0x2af9

If clearing the proxy server settings in the client machine’s web browser still does not restore IP-HTTPS connectivity, it may be that a proxy server is also configured for winhttp. You can confirm this by opening an elevated PowerShell command window and running the netsh winhttp show proxy command.

DirectAccess IP-HTTPS Error 0x2af9

To clear the winhttp proxy server settings run the netsh winhttp reset proxy command.

DirectAccess IP-HTTPS Error 0x2af9

Additional Resources

DirectAccess Expired IP-HTTPS Certificate and Error 0x800b0101

DirectAccess IP-HTTPS Preauthentication

DirectAccess SSL Offload and IP-HTTPS Preauthentication with Citrix NetScaler

DirectAccess SSL Offload using F5 BIG-IP

DirectAccess IP-HTTPS Preauthentication with F5 BIG-IP

DirectAccess and Multi-SAN SSL Certificates for IP-HTTPS

Implementing DirectAccess with Windows Server 2016 Book

 

DirectAccess SSL Offload and IP-HTTPS Preauthentication with Citrix NetScaler

Introduction

Communication between the DirectAccess client and server takes place exclusively over IPv6. When DirectAccess servers and/or clients are on the IPv4 Internet, an IPv6 transition technology must be employed to allow those clients to connect to the DirectAccess server. DirectAccess deployment best practices dictate that only the IP-HTTPS IPv6 transition technology be used. IP-HTTPS uses SSL/TLS for server authentication and optionally encryption. To improve security and performance for IP-HTTPS, an Application Delivery Controller (ADC) like the Citrix NetScaler can be configured to perform SSL offloading and client preauthentication for DirectAccess IP-HTTPS connections.

Please note that the following caveats apply when enabling SSL offload for DirectAccess clients:

  • Enabling SSL offload and IP-HTTPS preauthentication on an ADC for DirectAccess is formally unsupported by Microsoft.
  • SSL offload should not be enabled with DirectAccess is configured to use one-time password (OTP) authentication. Offloading SSL will break OTP functionality.

IP-HTTPS Challenges

The IP-HTTPS IPv6 transition technology is a simple and effective way to allow DirectAccess clients and servers to communicate by encapsulating IPv6 traffic in HTTP and routing it over the public IPv4 Internet. However, there are two critical issues with the default implementation of IP-HTTPS in DirectAccess. One is a security issue, the other affects performance.

Security

The DirectAccess server does not authenticate clients establishing IP-HTTPS connections. This could allow an unauthorized client to obtain an IPv6 address from the DirectAccess server using the IPv6 Neighbor Discovery (ND) process. With a valid IPv6 address, the unauthorized user could perform internal network reconnaissance or launch a variety of Denial of Service (DoS) attacks on the DirectAccess infrastructure and connected clients. More details here.

Performance

Windows 7 DirectAccess clients use encrypted cipher suites when establishing IP-HTTPS connections. However, the payload being transported is already encrypted using IPsec. This double encryption increases resource utilization on the DirectAccess server, reducing performance and limiting scalability. More details here.


Note: Beginning with Windows Server 2012 and Windows 8, Microsoft introduced support for null encryption for IP-HTTPS connections. This eliminates the needless double encryption, greatly improving scalability and performance for DirectAccess clients using IP-HTTPS.


SSL Offload for DirectAccess IP-HTTPS

The Citrix NetScaler can be configured to perform SSL offload to improve performance for Windows 7 DirectAccess clients using IP-HTTPS. Since DirectAccess does not natively support SSL offload, the NetScaler must be configured in a non-traditional way. While the NetScaler will be configured to terminate incoming IP-HTTPS SSL connections, it must also use SSL for the back-end connection to the DirectAccess server. However, the NetScaler will be configured only to use null cipher suites when connecting to the DirectAccess server. Even though Windows 7 clients will still perform double encryption to the NetScaler, this configuration effectively offloads from the server the heavy burden of double encrypting every IP-HTTPS connection for all connected DirectAccess clients. This results in reduced CPU utilization on the DirectAccess server, yielding better scalability and performance.

SSL Offload and Windows 8.x/10 Clients

Offloading SSL for Windows 8.x/10 clients will not improve performance because they already use null cipher suites for IP-HTTPS when connecting to a Windows Server 2012 or later DirectAccess server. However, terminating SSL on the NetScaler is still required to perform IP-HTTPS preauthentication.

Supported NetScaler Platforms for DirectAccess SSL Offloading

The following configuration for Citrix NetScaler can be performed on any release of the VPX virtual ADC platform. However, be advised that there is a known issue with older releases on the MDX and SDX hardware platforms that will prevent this from working. For MDX and SDX deployments, upgrading to release 11.1 build 50.10 or later will be required.

Configure Citrix NetScaler for IP-HTTPS SSL Offload

To enable SSL offloading for DirectAccess IP-HTTPS on the Citrix NetScaler, open the NetScaler management console, expand Traffic Management and Load Balancing, and then perform the following procedures in order.

Add Servers

  1. Click Servers.
  2. Click Add.
  3. In the Name field enter a descriptive name for the first DirectAccess server.
  4. Select IP Address.
  5. In the IP Address field enter the IP address of the first DirectAccess server.
  6. Click Create.
  7. Repeat these steps for any additional servers in the load-balanced cluster.

DirectAccess SSL Offload and IP-HTTPS Preauthentication with Citrix NetScaler

Add Services

  1. Click Services.
  2. Click Add.
  3. In the Service Name field enter a descriptive name for the service.
  4. Select Existing Server from the Server drop-down list.
  5. Choose the first DirectAccess server in the cluster.
  6. Choose SSL from the Protocol drop-down list.
  7. Click Ok.DirectAccess SSL Offload and IP-HTTPS Preauthentication with Citrix NetScaler
  8. Edit SSL Parameters.
    1. In the Protocol section uncheck SSLv3.
    2. Click Ok.
  9. Edit SSL Ciphers.
    1. Click Remove All.
    2. Click Add.
    3. Type NULL in the Search Ciphers box.
    4. Check the box next to the first entry for SSL3-NULL-SHA.
    5.  Click the right arrow to add the cipher to the list.
    6. Click Ok.
    7. Click Done.
    8. Repeat these steps for any additional servers in the load-balanced cluster.DirectAccess SSL Offload and IP-HTTPS Preauthentication with Citrix NetScaler

A warning message may be displayed indicating that no usable ciphers are configured on the SSL vserver/service. This message can be safely ignored.

DirectAccess SSL Offload and IP-HTTPS Preauthentication with Citrix NetScaler

Add Virtual Server

  1. Click Virtual Servers.
    1. Click Add.
    2. In the Name field enter a descriptive name for the virtual server.
    3. Choose SSL from the Protocol drop-down list.
    4. In the IP Address field enter the IP address for the virtual server.
    5. Click Ok.DirectAccess SSL Offload and IP-HTTPS Preauthentication with Citrix NetScaler

      Note: When enabling load balancing in DirectAccess, the IP address assigned to the first DirectAccess server is reallocated for use as the load balancing Virtual IP Address (VIP). Ideally this IP address will be assigned to the load balancing virtual server on the NetScaler. However, this is not a hard requirement. It is possible to configure the VIP on the NetScaler to reside on any subnet that the load balancer has an interface to. More details here.


  2. In the Services and Groups section click No Load Balancing Virtual Server Service Binding.
    1. Click on the Select Service field.
    2. Check all DirectAccess server services and click Select.
    3. Click Bind.
    4. Click Continue.
  3. In the Certificate section click No Server Certificate.
    1. Click on the Select Server Certificate field.
    2. Choose the certificate to be used for DirectAccess IP-HTTPS.
    3. Click Select.
    4. Click Bind.
    5. Click Continue.
  4. Edit SSL Ciphers.
    1. Click Remove All.
    2. Click Add.
    3. Type ECDHE in to the Search Ciphers box.
    4. Check the box next to TLS1-ECDHE-RSA-AES128-SHA.
    5. Click the right arrow to add the cipher to the list.
    6. Type NULL in to the Search Ciphers box.
    7. Check the box next to SSL3-NULL-SHA.
    8. Click the right arrow to add the cipher to the list.
    9. Click Ok.
    10. Click Done.DirectAccess SSL Offload and IP-HTTPS Preauthentication with Citrix NetScaler

      Note: If Windows 8.x/10 clients are supported exclusively, SSL3-NULL-SHA is the only cipher suite required to be configured on the virtual server. If Windows 7 client support is required, the TLS1-ECDHE-RSA-AES128-SHA cipher suite should also be configured on the virtual server.


  5. Edit SSL Parameters.
    1. Uncheck SSLv3.
    2. Click Ok.

      Note: If Windows 8.x/10 clients are supported exclusively, TLSv1 can also be unchecked on the virtual server. If Windows 7 client support is required, TLSv1 must be enabled.


  6. In the Advanced Settings section click Persistence.
    1. Choose SSLSESSION.
    2. Enter 10 minutes for the Time-out (mins) value.
    3. Click Ok.
    4. Click Done.

Optional IP-HTTPS Preauthentication

To enable IP-HTTPS preauthentication to prevent unauthorized network access, perform the following procedures on the Citrix NetScaler appliance.

  1. Expand Traffic Management, Load Balancing, and then click Virtual Servers.
  2. Select the DirectAccess virtual server and click Edit.
    1. In the Certificate section click No CA Certificate.
    2. Click the Select CA Certificate field.
    3. Choose the certificate for the CA that issues certificates to DirectAccess clients and servers.

      Note: The CA certificate used for DirectAccess can be found by opening the Remote Access Management console, clicking Edit on Step 2, and then clicking Authentication. Alternatively, the CA certificate can be found by running the following PowerShell command.

      (Get-RemoteAccess).IPsecRootCertificate | Format-Table Thumbprint


    4. Click Select.
    5. Choose CRL Optional from the CRL and OCSP Check drop-down list.
    6. Click Bind.
  3. Edit SSL Parameters.
    1. Check the box next to Client Authentication.
    2. Choose Mandatory from the Client Certificate drop-down list.
    3. Click Ok.
    4. Click Done.
      DirectAccess SSL Offload and IP-HTTPS Preauthentication with Citrix NetScaler

Summary

Leveraging the advanced capabilities of the Citrix NetScaler ADC can improve performance when supporting Windows 7 clients and enhance security for all DirectAccess clients using IP-HTTPS. In terms of supportability, all of the changes described in this article are completely transparent and do not alter the native DirectAccess client or server configuration. If a Microsoft support engineer declines support due to this configuration, switching from SSL offload to SSL bridge is all that’s required to restore full supportability.

Additional Resources

NetScaler release 11.1 build 50.10 (requires login) – https://www.citrix.com/downloads/netscaler-adc/firmware/release-111-build-5010

Release notes for build 50.10 of NetScaler 11.1 release – https://www.citrix.com/content/dam/citrix/en_us/documents/downloads/netscaler-adc/NS_11_1_50_10.html

VIDEO: Enable Load Balancing for DirectAccess – https://www.youtube.com/watch?v=3tdqgY9Y-uo

DirectAccess IP-HTTPS preauthentication using F5 BIG-IP – https://directaccess.richardhicks.com/2016/05/23/directaccess-ip-https-preauthentication-using-f5-big-ip/

DirectAccess SSL offload for IP-HTTPS using F5 BIG-IP – https://directaccess.richardhicks.com/2013/07/10/ssl-offload-for-ip-https-directaccess-traffic-from-windows-7-clients-using-f5-big-ip/

Implementing DirectAccess with Windows Server 2016 book – http://directaccessbook.com/

DirectAccess IP-HTTPS Preauthentication using Citrix NetScaler

Note: For information about configuring the F5 BIG-IP to perform IP-HTTPS preauthentication, click hereFor information about configuring Windows Server 2012 R2 or Windows Server 2016 to perform IP-HTTPS preauthentication natively, click here.

Introduction

DirectAccess IP-HTTPS Preauthentication using Citrix NetScalerIP-HTTPS is an IPv6 transition technology used by DirectAccess. It enables DirectAccess clients to communicate with the DirectAccess server using IPv6 over the public IPv4 Internet by encapsulating IPv6 packets in HTTP and authenticating (and optionally encrypting) them using SSL/TLS. IP-HTTPS is supported for all DirectAccess network deployment configurations and is enabled by default.

When a DirectAccess client connection is established, only the server is authenticated by the client. The client is not authenticated by the server. The DirectAccess server will thus accept IP-HTTPS connections from any client, valid or not.

IP-HTTPS Connection

Once a client has established an IP-HTTPS transition tunnel, it will go through the standard IPv6 neighbor discovery process to identify routers and obtain an IPv6 prefix for the link. It will use this information to build its own IPv6 address, which it uses to communicate with the DirectAccess server and begin establishing IPsec security associations for DirectAccess.

ICMP and IPsec

By design, ICMP is exempt from DirectAccess IPsec policy processing. If an unauthorized client were to establish an IP-HTTPS transition tunnel, even without authentication (Kerberos Proxy or certificate) it would be able to ping the DirectAccess server tunnel endpoint IPv6 addresses, the DNS64 IPv6 address, and any intranet hosts (assuming host firewalls allow this access).

Security Risk

This default posture opens up the DirectAccess server and intranet to unauthorized remote network reconnaissance and some IPv6-related Denial-of-Service (DoS) attacks. These were demonstrated by security researcher Ali Hardudi at the recent Troopers16 security conference. You can view his very informative session here.

Note: DirectAccess IPsec data connections are unaffected and are completely secure. Data is never exposed at any time with the default configuration.

IP-HTTPS Preauthentication

DirectAccess IP-HTTPS Preauthentication using Citrix NetScalerTo mitigate these risks, it is recommended that an Application Delivery Controller (ADC) such as the Citrix NetScaler be configured to preauthenticate DirectAccess clients prior to establishing the IP-HTTPS transition tunnel.

Note: To configure the F5 BIG-IP to perform IP-HTTPS preauthentication, click here.

Citrix NetScaler Configuration

To perform DirectAccess preauthentication, it will be necessary to configure the Citrix NetScaler to perform SSL termination for IP-HTTPS. The virtual server on the NetScaler must use the SSL protocol. In addition, a CA certificate must be bound to the virtual server. Also, Client Authentication must be enabled under SSL Parameters and be set to Mandatory.

DirectAccess IP-HTTPS Preauthentication using Citrix NetScaler

Once configured, the NetScaler appliance will ensure that the DirectAccess IPsec certificate is present on the client before establishing the IP-HTTPS IPv6 transition tunnel. This will prevent unauthorized connections to the DirectAccess server.

Important Considerations

Performing IP-HTTPS preauthentication on the Citrix NetScaler is formally unsupported by Microsoft. In addition, terminating IP-HTTPS on the NetScaler appliance breaks OTP authentication.

Summary

The default security posture of DirectAccess leaves the internal network open to unauthorized network reconnaissance, and exposes the DirectAccess infrastructure to potential denial-of-service (DoS) attacks. To mitigate these security risks, implement the Citrix NetScaler ADC and enable client certificate authentication.

References

Security Assessment of Microsoft DirectAccess [Overview] – https://www.insinuator.net/2016/04/security-assessment-of-microsoft-directaccess/

Security Assessment of Microsoft DirectAccess [Full Document] – https://www.ernw.de/newsfeed/newsletter-53-may-2016-security-assessment-of-microsoft-directaccess/index.html

Security Assessment of Microsoft DirectAccess Troopers16 Presentation by Ali Hardudi [Video] – https://www.youtube.com/watch?v=wW1x7ow0V9w

Chiron IPv6 Penetration Testing Framework – https://www.insinuator.net/2014/10/chiron-an-all-in-one-ipv6-penetration-testing-framework/

IP-HTTPS specification on MSDN – https://msdn.microsoft.com/en-us/library/dd358571.aspx

Configure F5 BIG-IP to Perform IP-HTTPS Preauthentication – https://directaccess.richardhicks.com/2016/05/23/directaccess-ip-https-preauthentication-using-f5-big-ip/

Configure Windows Server 2012 R2  and Windows Server 2016 to Perform IP-HTTPS Preauthentication – https://directaccess.richardhicks.com/2016/06/13/directaccess-ip-https-preauthentication/

DirectAccess Multisite Geographic Redundancy with Microsoft Azure Traffic Manager

Introduction

DirectAccess Multisite Geographic Redundancy with Microsoft Azure Traffic ManagerTo provide geographic redundancy, DirectAccess can be deployed in a multisite configuration. In this scenario, Windows 8.x and Windows 10 clients are aware of all entry points in the enterprise and will automatically select the nearest available entry point to connect to. The nearest entry point is defined as the one that responds the quickest. When a Windows 8.x or Windows 10 client attempts to establish DirectAccess connectivity, an HTTP GET is sent to all entry points and the client will select the one with the shortest Round Trip Time (RTT) for the request.

Note: Windows 7 clients can be provisioned when DirectAccess is configured for multisite access, but they must be assigned to an individual entry point.

Challenges

There are a number of challenges that come with the default multisite configuration. Choosing an entry point based solely on network latency is rather simplistic and can often produce unexpected results. It also lacks support for granular traffic distribution or active/passive configuration.

GSLB

DirectAccess Multisite Geographic Redundancy with Microsoft Azure Traffic ManagerFor the best experience, DirectAccess can be configured to use a Global Server Load Balancing (GSLB) solution to enhance transparent site selection and failover for Windows 8.x and Windows 10 clients. Commonly this is implemented using an on-premises appliance (Citrix NetScaler, F5 Global Traffic Manager, Kemp LoadMaster, A10 Thunder, etc.). These solutions offer exceptional control over DirectAccess traffic distribution, but they add expense and complexity.

Azure Traffic Manager

Azure Traffic Manager is a cloud-based GSLB solution that is a simple and cost-effective alternative to dedicated on-premises appliances. While it does not offer all of the features that GSLB appliances provide, it does provide better traffic distribution options than the default configuration. Importantly, it enables active/passive failover, which is a common requirement not supported natively with DirectAccess.

DirectAccess Multisite Geographic Redundancy with Microsoft Azure Traffic Manager

Traffic Manager Configuration

In the Azure portal (the new one, not the old one!) click New, Networking, and then Traffic Manager profile.

DirectAccess Multisite Geographic Redundancy with Microsoft Azure Traffic Manager

Provide a name and select a Routing method.

DirectAccess Multisite Geographic Redundancy with Microsoft Azure Traffic Manager

Routing method options are Performance, Weighted and Priority.

  • Performance. Select this option to enable clients to connect to the entry point with the lowest network latency.
  • Weighted. Select this option to enable clients to prefer some entry points more than others. Assign a weight value of 1 to 1000 for each entry point. Higher values have more preference. Values for entry points can be the same, if desired.
  • Priority. Select this option to enable clients to connect to a primary entry point, then fail over to a secondary or tertiary entry point in the event of an outage. Assign a priority value of 1 to 1000 for each entry point. Lower values take precedence. Each entry point must be assigned a unique priority value.

Click Create when finished. Next click Settings for the new traffic manager profile and click Configuration. Change Protocol to HTTPS, Port to 443, and Path to /IPHTTPS. Click Save when finished.

DirectAccess Multisite Geographic Redundancy with Microsoft Azure Traffic Manager

Next click Endpoints and click Add. Select External endpoint from the drop down list, provide a descriptive name, and then enter the Fully-Qualified Domain Name (FQDN) of the first DirectAccess entry point. When using the Performance routing method, choose a location that best represents the geography where the DirectAccess entry point is located. When using the Weighted or Priority routing methods, specify an appropriate value accordingly. Click Ok when finished. Repeat these steps for each entry point in the organization.

DirectAccess Multisite Geographic Redundancy with Microsoft Azure Traffic Manager

DirectAccess Configuration

In the Remote Access Management console, highlight DirectAccess and VPN below Configuration in the navigation tree and then click Configure Multisite Settings below Multisite Deployment in the Tasks pane. Click Global Load Balancing and choose Yes, use global load balancing. Enter the FQDN of the Azure Traffic Manager profile and click Next, and then click Commit.

DirectAccess Multisite Geographic Redundancy with Microsoft Azure Traffic Manager

Note: An SSL certificate with a subject name matching that of the GSLB FQDN is not required.

In some cases, the management console may report that global load balancing addresses cannot be identified automatically for some or all entry points.

DirectAccess Multisite Geographic Redundancy with Microsoft Azure Traffic Manager

If this occurs, it will be necessary to run the Set-DAEntryPoint PowerShell cmdlet to assign GLSB IP addresses to each entry point. The GSLB IP address is the public IPv4 address that the entry point public hostname resolves to.

Set-DAEntryPoint -Name [entrypoint_name] -GslbIP [external_ip_address]

For example:

Set-DAEntryPoint -Name "US West" -GslbIP 203.0.113.195
Set-DAEntryPoint -Name "US East" -GslbIP 198.51.100.21

Summary

DirectAccess includes native functionality to enable geographic load balancing for Windows 8.x and Windows 10 clients. The site selection process used by DirectAccess clients in this scenario is basic, and has the potential to yield unexpected results. Azure Traffic Manager is a simple, cost-effective alternative to dedicated on-premises GSLB appliances. It can be integrated with DirectAccess to address some of the shortcomings with the native entry point selection process.

Additional Resources

DirectAccess and Multi-SAN SSL Certificates for IP-HTTPS

Introduction

When preparing a DirectAccess server, an SSL certificate is required for the IP-HTTPS IPv6 transition technology. This certificate is often issued by a public Certification Authority (CA), but it can also be issued an organization’s internal Public Key Infrastructure (PKI).

SSL Certificate

Commonly an SSL certificate is issued for a single hostname, or subject. As long as the hostname matches the subject, everything works fine.

DirectAccess and Multi-SAN SSL Certificates for IP-HTTPS

Multi-SAN SSL Certificate

To ease the management burden of using multiple certificates, or reduce the expense associated with using a wildcard certificate, organizations can request a multi-SAN (Subject Alternative Name) certificate, which matches more than one subject. The additional subjects are included in the Subject Alternative Name field on the SSL certificate.

DirectAccess and Multi-SAN SSL Certificates for IP-HTTPS
A single multi-SAN certificate can be installed on multiple hosts and will work without issue as long as the hostname matches one of the SAN entries.

DirectAccess and Multi-SAN Certificates

When implementing DirectAccess in a multisite configuration, each entry point in the organization will have a unique public hostname. Instinctively, using a multi-SAN SSL certificate in this scenario would seem ideal.

Unfortunately, support for multi-SAN SSL certificates with DirectAccess is limited. To use a multi-SAN certificate for DirectAccess IP-HTTPS, the public hostname must match the name listed in the Subject field. In the example above, the subject is da.richardhicks.net, with SAN entries for da-west.richardhicks.net and da-east.richardhicks.net.

In this scenario, only the public name da.richardhicks.net is supported for use with DirectAccess. It will not work for any of the SAN entries. For example, attempting to configure DirectAccess to use this certificate with the public hostname da-west.richardhicks.net will fail with the following error message.

The subject name of certificate CN=[certificate subject name] is invalid.
Select a certificate with a valid subject name.

DirectAccess and Multi-SAN SSL Certificates for IP-HTTPS

Attempting to work around this issue by using the Set-DAServer PowerShell cmdlet also fails to recognize the SSL certificate correctly.

DirectAccess and Multi-SAN SSL Certificates for IP-HTTPS

Summary

Using a multi-SAN SSL certificate for the DirectAccess IP-HTTPS IPv6 transition technology is only supported when the public hostname matches the subject name of the certificate. Configuring DirectAccess with a public hostname listed in the SAN list is not supported. For multisite DirectAccess deployments, individual certificates must be issued for each entry point. Alternatively, a wildcard certificate can be used.

DirectAccess Deep Dive Training at TechMentor Las Vegas 2016

TechMentor Las Vegas 2016Looking for in-depth DirectAccess technical training? Join me at the TechMentor Conference March 7 to 11, 2016 at the Bally’s Hotel in Las Vegas, Nevada. There I will be delivering a three-hour deep-dive DirectAccess training session covering installation, configuration, and troubleshooting of DirectAccess on Windows Server 2012 R2. The conference also features many other excellent training sessions by industry experts like Don Jones, Greg Shields, Jeff Hicks, Ed Horley, and many more. Register now and save!

Windows Clients Do Not Receive DirectAccess Configuration Changes

Windows Clients Do Not Receive DirectAccess Configuration Changes

A scenario can occur in which changes to the DirectAccess configuration made using the Remote Access Management console or at the command line using PowerShell are not reflected on the DirectAccess client, even after receiving the latest group policy updates. The issue occurs for DirectAccess clients that are provisioned with the Offline Domain Join (ODJ, or djoin.exe) tool.

When the ODJ provisioning package is initially created, it does not add the new computer account to the DirectAccess security group. The ODJ-provisioned client receives all DirectAccess configuration settings at the time of provisioning, but it will not receive subsequent changes to the DirectAccess configuration made after it was originally provisioned.

To resolve this issue, be sure to proactively add the DirectAccess client’s computer account to the appropriate DirectAccess security group in Active Directory after provisioning with ODJ using Active Directory Users and Computers (ADUC), the Active Directory Administrative Center (ADAC), or by executing the following PowerShell command:

Add-ADGroupMember -Identity [DirectAccess Client Security Group] -Members [computername]

Once the DirectAccess client has been added to the security group and restarted, it will then receive DirectAccess configuration settings changes going forward.

Configuring Multicast NLB for DirectAccess

Introduction

DirectAccess in Windows Server 2012 R2 includes support for load balancing using either Windows Network Load Balancing (NLB) or an external physical or virtual load balancer. There are advantages and disadvantages to each, but NLB is commonly deployed due to its cost (free!) and relative ease of configuration. NLB has three operation modes – Unicast, Multicast, and IGMP Multicast. It may become necessary to change the NLB operation mode depending on the environment where DirectAccess is deployed. This article describes when and how to make those changes.

Default Configuration

When NLB is first configured, the default cluster operation mode is set to Unicast. In this configuration, all nodes in the NLB cluster share the same MAC address. The NLB kernel mode driver prevents the switch from learning the MAC address for any node in the cluster by masking it on the wire. When a frame is delivered to the switch where the NLB cluster resides, without a MAC address to switch port mapping the frame is delivered to all ports on the switch. This induces switch flooding and is by design. It is required for all nodes in the cluster to “see” all traffic. The NLB driver then determines which node will handle the request.

NLB on Hyper-V

Unicast NLB typically works without issue in most physical environments. However, enabling NLB when the DirectAccess server is running on a virtual machine requires some additional configuration. For Hyper-V, the only thing that is required is to enable MAC Address Spoofing on the virtual network adapter as I discussed here. No other changes are required.

NLB on VMWare

For VMware environments, it will be necessary to change the cluster operation mode from unicast to multicast. This is because the VMware hypervisor proactively informs the virtual switch of the virtual machine’s MAC address on startup and during other virtual networking events. When this occurs, all traffic for the NLB Virtual IP Address (VIP) will be delivered to a single node in the cluster. In multicast operation mode, all nodes in the NLB cluster retain their original MAC address and a unique MAC address is assigned to the cluster VIP. As such, there’s no need to prevent the switch from learning the virtual machine’s MAC address.

Configuring Multicast NLB

To enable Multicast NLB, first enable load balancing for DirectAccess using the Remote Access Management console as usual. DO NOT perform the initial configuration of NLB outside of the Remote Access Management console! Before adding another member to the array, open the Network Load Balancing Manager, right-click the cluster and choose Cluster Properties. Select the Cluster Parameters tab and change the Cluster operation mode to Multicast.

Configuring Multicast NLB for DirectAccess

When opening the Network Load Balancing Manager locally on the DirectAccess server, you may receive the following error message:

“Running NLB Manager on a system with all networks bound to NLB might
not work as expected. If all interfaces are set to run NLB in “unicast”
mode, NLB manager will fail to connect to hosts.”

Configuring Multicast NLB for DirectAccess

If you encounter this error message it will be necessary to run the NLB Manager on another host. You can install the NLB Manager on a Windows Server 2012 R2 system by using the following PowerShell command.

Install-WindowsFeature RSAT-NLB

Optionally you can download and install the Windows Remote Server Administration Tools (RSAT) on a Windows desktop client and manage NLB remotely.

Once this change has been made you can add additional DirectAccess servers to the array using the Remote Access Management console.

Additional Configuration

If you cannot communicate with the cluster VIP from a remote subnet, but can connect to it while on the same subnet, it might be necessary to configure static ARP entries on any routers for the subnet where the NLB cluster resides. Often this is required because routers will reject responses to ARP requests that are from a host with a unicast IP address but have a multicast MAC address.

DirectAccess, Windows 10, and Network Access Protection (NAP)

Windows 10, DirectAccess, and NAPFirst introduced with Windows Server 2008, Microsoft Network Access Protection (NAP) is a technology that allows IT administrators to create and enforce system health requirements that must be met before a computer can connect to the network. Common NAP enforcement points include Ethernet switches (802.1x), DHCP, IPsec, remote access VPN, and Terminal Services Gateway (TS Gateway) connections. DirectAccess also supports NAP integration, which allows administrators to extend this solution to include their DirectAccess clients.

Unfortunately, NAP has proven not to be very popular, and the adoption rate for this technology has been quite minimal. With that, Microsoft formally deprecated NAP in Windows Server 2012 R2, and removed it completely from Windows Server 2016.

Crucially the plumbing for NAP integration in the Windows 10 client operating system has also been removed. For DirectAccess deployments that have been configured to use NAP, this obviously presents a problem. In this scenario, Windows 7/8 clients will function normally. However, Windows 10 clients will not be able to connect. Since NAP integration with DirectAccess is a global setting, all clients must conform to NAP. There is no option to exclude only Windows 10 clients from NAP.

DirectAccess, Windows 10, and NAP

There are two ways in which to resolve this problem. The first is simply to disable NAP integration. However, if you still want to enforce NAP requirements for Windows 7/8 clients, but at the same time also want to allow Windows 10 clients to use DirectAccess, a separate dedicated DirectAccess deployment without NAP integration configured will have to be deployed to support Windows 10 DirectAccess clients.

DirectAccess DNS Not Working Properly

Name resolution and proper DNS server configuration is vital to the functionality of DirectAccess. When performing initial configuration of DirectAccess, or making changes to the DNS server configuration after initial configuration, you may notice the operations status for DNS indicates Critical, and that the operations state shows Server responsiveness.

DirectAccess DNS Not Working Correctly

Highlighting the DNS server on the Operations Status page and viewing the details shows that DNS is not working properly with the following error message:

None of the enterprise DNS servers <IPv6_address> used by DirectAccess
clients for name resolution are responding. This might affect DirectAccess
client connectivity to corporate resources.

DirectAccess DNS Not Working Correctly

There are a number of things that can contribute to this problem, but a common cause is an error made when assigning a DNS server to a specific DNS suffix. An inexperienced DirectAccess administrator might specify the IPv4 address of an internal corporate DNS server, which is incorrect. The DNS server IPv4 address should be the address assigned to the DirectAccess server’s internal network interface.

The best way to ensure that the DNS server is configured correctly for DirectAccess is to delete the existing entry and then click Detect.

DirectAccess DNS Not Working Correctly

An IPv6 address will be added automatically. This is the IPv6 address of the DNS64 service running on the DirectAccess server, which is how the DNS server should be configured for proper DirectAccess operation.

DirectAccess DNS Not Working Correctly

Once the changes have been saved and applied, the DNS server should once again respond and the status should return to Working.

DirectAccess DNS Not Working Correctly

%d bloggers like this: