Top 5 DirectAccess Troubleshooting PowerShell Commands

Top 5 DirectAccess Troubleshooting PowerShell CommandsNative PowerShell commands in Windows 10 make DirectAccess troubleshooting much easier than older operating systems like Windows 7. For example, with one PowerShell command an administrator can quickly determine if a DirectAccess client has received the DirectAccess client settings policy. In addition, PowerShell can be used to view the status of the connection and retrieve additional information or error codes that can be helpful for determining the cause of a failed connection. Further, PowerShell can also be used to review configuration details and perform other troubleshooting and connectivity validation tasks.

Here are my top 5 PowerShell commands for troubleshooting DirectAccess on Windows 10.

1. Get-DAClientExperienceConfiguration

Ensuring that the DirectAccess Client Settings group policy has been applied to the client is one of the first steps in troubleshooting failed DirectAccess connections. While it is possible to use gpresult to do this, using the Get-DAClientExperienceConfiguration PowerShell command is much simpler. If DirectAccess client settings have been applied, the output of the command will include information such as the IPsec tunnel endpoint IPv6 addresses and the Network Connectivity Assistant (NCA) corporate resource URL. If DirectAccess client settings have not been applied, this information will be missing.

Top 5 DirectAccess Troubleshooting PowerShell Commands

Figure 1. DirectAccess Client Settings group policy successfully applied.

Top 5 DirectAccess Troubleshooting PowerShell Commands

Figure 2. DirectAccess Client Settings group policy not applied.

2. Get-NetIPHttpsState

Performance improvements first introduced in Windows 8 have made IP-HTTPS the IPv6 transition technology of choice when it comes to supporting DirectAccess client connectivity. Also, if the DirectAccess server is located behind an edge device performing Network Address Translation (NAT), IP-HTTPS is the only supported transition technology. Using the Get-NetIPHttpsState PowerShell command, the DirectAccess administrator can quickly determine if the IP-HTTPS connection was successful. If it was not, the command will return an error code and interface status that will indicate why the IP-HTTPS connection was unsuccessful.

Top 5 DirectAccess Troubleshooting PowerShell Commands

Figure 3. Get-NetIPHttpsState

3. Get-NetIPHttpsConfiguration

When troubleshooting IP-HTTPS connection failures, it is necessary to obtain additional information to continue the troubleshooting process. Using the Get-NetIPHttpsConfiguration PowerShell command, the DirectAccess administrator can obtain the public hostname for the DirectAccess server and ensure that the name resolves to the correct IP address in DNS and that it is reachable on TCP port 443.

Top 5 DirectAccess Troubleshooting PowerShell Commands

Figure 4. Get-NetIPHttpsConfiguration

4. Resolve-DnsName

Using the Resolve-DnsName PowerShell command is crucial when performing any name resolution tasks on the DirectAccess client. This is because Resolve-DnsName is aware of the Name Resolution Policy Table (NRPT) and will direct name resolution requests accordingly. Tools like nslookup are DNS server testing tools and are unaware of the NRPT. Typically they do not yield expected results when testing name resolution on a DirectAccess client.

Top 5 DirectAccess Troubleshooting PowerShell Commands

Figure 5. Name resolution results from Resolve-DnsName and nslookup.

5. Get-DnsClientNrptPolicy

Often the cause of DirectAccess client connectivity issues is a misconfigured NRPT. Using the Get-DnsClientNrptPolicy PowerShell command the DirectAccess administrator can validate that name resolution requests for host names in any internal namespaces are being sent to the DirectAccess DNS64 IPv6 address.

Top 5 DirectAccess Troubleshooting PowerShell Commands

Figure 6. Get-DnsClientNrptPolicy

Additional Resources

Top 5 DirectAccess Troubleshooting Tips

Troubleshooting Name Resolution Issues on DirectAccess Clients

Learn PowerShell in a Month of Lunches Book by Don Jones and Jeff Hicks

Implementing DirectAccess with Windows Server 2016 Book

Planning and Implementing DirectAccess with Windows Server 2016 Video Training Course

Managing and Supporting DirectAccess with Windows Server 2016 Video Training Course

 

 

DirectAccess Network Connectivity Assistant (NCA) Configuration Guidance

DirectAccess Network Connectivity Assistant (NCA) Configuration GuidanceThe DirectAccess Network Connectivity Assistant (NCA), first introduced in Windows 8, provides DirectAccess connectivity status information as well as diagnostic support on the client. The NCA validates that DirectAccess is working end-to-end by attempting to reach internal resources defined by the administrator during the configuration of DirectAccess. NCA configuration and operation is a source of much confusion. This article serves to provide best practice configuration guidance for the NCA to ensure optimum and reliable operation.

NCA Operation

When a DirectAccess client is outside the corporate network, it will attempt to establish a DirectAccess connection any time it has an active Internet connection. After a DirectAccess connection is made, the NCA will attempt to validate DirectAccess connectivity by verifying availability of corporate resources as defined in the DirectAccess configuration (Remote Access Management console, Step 1, Edit, Network Connectivity Assistant).

If the NCA can reach the defined internal corporate resource(s), the DirectAccess connection is verified end-to-end and it will report the connection status as “Connected”. If it fails to connect to any internal corporate resource, it displays “Connecting”.

DirectAccess Network Connectivity Assistant (NCA) Configuration Guidance

Figure 1. NCA successfully validated internal corporate resource connectivity.

DirectAccess Network Connectivity Assistant (NCA) Configuration Guidance

Figure 2. NCA failed to connect to one or more corporate resources.

NCA Configuration

When first installing DirectAccess, the Remote Access Setup wizard will collect information to be used by the NCA, including corporate resources, helpdesk email address, and DirectAccess connection name. It will also provide the option to allow DirectAccess clients to use local name resolution.

Note: The NCA settings configured in the Remote Access Management console pertain only to Windows 8.x and Windows 10 clients. They are not used by Windows 7 clients at all.

DirectAccess Network Connectivity Assistant (NCA) Configuration Guidance

Intuitively it would appear that information needs to be entered in the Resource and Type fields. However, it is recommended to leave this blank when first configuring DirectAccess. This is because the Remote Access Setup Wizard will automatically populate this field later. Specifying a resource during initial configuration will result in two entries being included, as shown here.

DirectAccess Network Connectivity Assistant (NCA) Configuration Guidance

As you can see, the Remote Access Setup wizard automatically added the resource directaccess-WebProbeHost.<internal domain.>. A corresponding DNS record is created that resolves this hostname to the internal IPv4 address of the DirectAccess server. In this configuration, the DirectAccess server itself serves as the corporate resource used by the NCA.

Multiple Corporate Resources

Having more than one resource to validate connectivity to the internal network is problematic though. If there are multiple entries specified, they must ALL pass a validation check from the client to report the connection status as “Connected”. Some administrators configure multiple entries with the mistaken belief that it will provide redundancy for the NCA, but it actually has the opposite effect. Having more than one entry only increases the chance of a false positive.

NCA Configuration Best Practices

It is recommended that only a single corporate resource URL be defined for the NCA. The default directaccess-WebProbeHost running on the DirectAccess server can be used, or, alternatively, another internal web server can be specified if desired. Any web server will work, including Microsoft Internet Information Services (IIS), Apache, NGINX, and most Application Delivery Controllers (ADCs) or load balancers. HTTPS is not required for the web probe host, only HTTP. If using an internal web server, ensure that it is highly available.

Do NOT use the Network Location Server (NLS) as a corporate resource! The NLS is exempted from the Name Resolution Policy Table (NRPT) on the client and is not reachable over DirectAccess. This will result in the NCA failing and reporting a “Connecting” status perpetually. In addition, avoid the use of PING for validating internal corporate resources. Ping uses ICMP which is inherently unreliable and commonly blocked by host and intermediary firewalls, making it an unreliable indicator of corporate network connectivity over DirectAccess.

Summary

The NCA is a crucial and often misunderstood component in the DirectAccess architecture. Follow the guidance outlined here to ensure that the NCA works reliably and effectively in your environment.

Additional Resources

DirectAccess Clients in Connecting State when using External Load Balancer
Planning and Implementing DirectAccess on Windows Server 2016 on Pluralsight
Implementing DirectAccess with Windows Server 2016 book

Top 5 DirectAccess Troubleshooting Tips

Top 5 DirectAccess Troubleshooting TipsDirectAccess is a thing of beauty when everything is working as it should. When it isn’t, troubleshooting can be quite challenging. DirectAccess relies on many Windows platform technologies such as Active Directory for authentication, PKI for certificate management, group policy for settings deployment, IPsec for encryption, and IPv6 for transport. With so many dependencies, locating the source of the problem can be a difficult and daunting task.

I’m frequently called upon to help organizations of all sizes with DirectAccess troubleshooting. While this post is not intended to be a detailed, prescriptive guide for DirectAccess troubleshooting, I did want to share some common troubleshooting tips based on many years of troubleshooting DirectAccess.

Here are my top 5 DirectAccess troubleshooting tips:

  1. Check Prerequisites – Before diving in and collecting network traces and scouring event logs for clues as to why DirectAccess isn’t working, it’s essential to start at the beginning. Often the source of trouble is missing or misconfigured prerequisites. For example, is the DirectAccess client running a supported operating system? Remember, clients must be running Windows 10 Enterprise or Education, Windows 8.x Enterprise, or Windows 7 Enterprise or Ultimate. Also, ensure that the Windows firewall is enabled on DirectAccess servers and clients, that certificates are installed and valid (trusted, correct EKU, etc.), and that the DirectAccess settings GPO has been applied to servers and clients.
  2. Validate External Connectivity – If you are following implementation and security best practices for DirectAccess, the DirectAccess server will be in a perimeter/DMZ network behind an edge firewall. The firewall must be configured to allow inbound TCP port 443 only. If the firewall is also performing Network Address Translation (NAT), the NAT rule must be configured to forward traffic to the DirectAccess server’s dedicated or virtual IP address (VIP), or the VIP of the load balancer. Watch for routing issues when using load balancers too. It’s a good idea to confirm external connectivity using the Test-NetConnection PowerShell command. Even better, use the open source tool Nmap for more thorough testing.
  3. Remove Third Party Software – I can’t tell you how many times I’ve resolved DirectAccess connectivity issues by removing (not just disabling!) third party software on the client and/or server. It’s not uncommon for third-party security software to interfere with IPsec and/or IPv6 communication, both of which are vital to DirectAccess. If your DirectAccess troubleshooting efforts reveal no underlying issues with prerequisites or external connectivity, I’d suggest removing (at least temporarily) any third-party software and testing again.
  4. Isolate Environmental Issues – Occasionally other settings applied manually or via Active Directory group policy will interfere with DirectAccess. Examples include IPv6 being disabled in the registry, IPv6 transition technologies required to support DirectAccess are turned off, essential firewall rules for DirectAccess are disabled, or manipulating local security settings such as Access this computer from the network. To assist with troubleshooting it might be necessary to temporarily place DirectAccess clients and servers in their own dedicated Organizational Units (OUs) and block inheritance to isolate the configuration as much as possible. In addition, if DirectAccess clients are servers are provisioned using images or templates, testing with a clean build straight from the installation source (ISO or DVD) can be helpful.
  5. Check for Unsupported Configurations – If DirectAccess isn’t working, it might be possible the configuration you are trying to use is not supported. Examples including strong user authentication with OTP when force tunneling is enabled, provisioning Windows 7 clients when using Kerberos Proxy authentication, or provisioning Windows 10 clients when Network Access Protection (NAP) integration is enabled. These configurations won’t work and are formally documented here.

This is by no means a comprehensive or exhaustive troubleshooting guide. For more information and additional DirectAccess troubleshooting guidance I would encourage you to purchase my book Implementing DirectAccess with Windows Server 2016, which has an entire chapter devoted just to troubleshooting. In addition, watch my DirectAccess video training courses on Pluralsight for details and information about DirectAccess installation, configuration, management, support, and troubleshooting. And if you’re still struggling to resolve a DirectAccess problem, use the form at the bottom of this page to contact me to inquire about additional troubleshooting help.

Additional Resources

Microsoft Windows DirectAccess Client Troubleshooting Tool
DirectAccess and Windows 10 Professional
DirectAccess Troubleshooting with Nmap
DirectAccess Unsupported Configurations
Planning and Implementing DirectAccess with Windows Server 2016 Video Training Course on Pluralsight
Implementing DirectAccess with Windows Server 2016 Book

Need assistance with DirectAccess troubleshooting? Complete the form below and I’ll get in touch with you.

Deployment Considerations for DirectAccess on Amazon Web Services (AWS)

Organizations are rapidly deploying Windows server infrastructure with public cloud providers such as Amazon Web Services (AWS) and Microsoft Azure. With traditional on-premises infrastructure now hosted in the cloud, DirectAccess is also being deployed there more commonly.

Supportability

Interestingly, Microsoft has expressly stated that DirectAccess is not formally supported on their own public cloud platform, Azure. However, there is no formal statement of non-support for DirectAccess hosted on other non-Microsoft public cloud platforms. With supportability for DirectAccess on AWS unclear, many companies are taking the approach that if it isn’t unsupported, then it must be supported. I’d suggest proceeding with caution, as Microsoft could issue formal guidance to the contrary in the future.

DirectAccess on AWS

Deploying DirectAccess on AWS is similar to deploying on premises, with a few notable exceptions, outlined below.

IP Addressing

It is recommended that an IP address be exclusively assigned to the DirectAccess server in AWS, as shown here.

Deployment Considerations for DirectAccess on Amazon Web Services (AWS)

Prerequisites Check

When first configuring DirectAccess, the administrator will encounter the following warning message.

“The server does not comply with some DirectAccess prerequisites. Resolve all issues before proceed with DirectAccess deployment.”

The warning message itself states that “One or more network adapters should be configured with a static IP address. Obtain a static address and assign it to the adapter.

Deployment Considerations for DirectAccess on Amazon Web Services (AWS)

IP addressing for virtual machines are managed entirely by AWS. This means the DirectAccess server will have a DHCP-assigned address, even when an IP address is specified in AWS. Assigning static IP addresses in the guest virtual machine itself is also not supported. However, this warning message can safely be ignored.

No Support for Load Balancing

It is not possible to create load-balanced clusters of DirectAccess servers for redundancy or scalability on AWS. This is because enabling load balancing for DirectAccess requires the IP address of the DirectAccess server be changed in the operating system, which is not supported on AWS. To eliminate single points of failure in the DirectAccess architecture or to add additional capacity, multisite must be enabled. Each additional DirectAccess server must be provisioned as an individual entry point.

Network Topology

DirectAccess servers on AWS can be provisioned with one or two network interfaces. Using two network interfaces is recommended, with the external network interface of the DirectAccess server residing in a dedicated perimeter/DMZ network. The external network interface must use either the Public or Private Windows firewall profile. DirectAccess will not work if the external interface uses the Domain profile. For the Public and Private profile to be enabled, domain controllers must not be reachable from the perimeter/DMZ network. Ensure the perimeter/DMZ network cannot access the internal network by restricting network access in EC2 using a Security Group, or on the VPC using a Network Access Control List (ACL) or custom route table settings.

External Connectivity

A public IPv4 address must be associated with the DirectAccess server in AWS. There are several ways to accomplish this. The simplest way is to assign a public IPv4 address to the virtual machine (VM). However, a public IP address can only be assigned to the VM when it is deployed initially and cannot be added later. Alternatively, an Elastic IP can be provisioned and assigned to the DirectAccess server at any time.

An ACL must also be configured for the public IP that restricts access from the Internet to only inbound TCP port 443. To provide additional protection, consider deploying an Application Delivery Controller (ADC) appliance like the Citrix NetScaler or F5 BIG-IP to enforce client certificate authentication for DirectAccess clients.

Network Location Server (NLS)

If an organization is hosting all of its Windows infrastructure in AWS and all clients will be remote, Network Location Server (NLS) availability becomes much less critical than with traditional on-premises deployments. For cloud-only deployments, hosting the NLS on the DirectAccess server is a viable option. It eliminates the need for dedicated NLS, reducing costs and administrative overhead. If multisite is configured, ensure that the NLS is not using a self-signed certificate, as this is unsupported.

Deployment Considerations for DirectAccess on Amazon Web Services (AWS)

However, for hybrid cloud deployments where on-premises DirectAccess clients share the same internal network with cloud-hosted DirectAccess servers, it is recommended that the NLS be deployed on dedicated, highly available servers following the guidance outlined here and here.

Client Provisioning

All supported DirectAccess clients will work with DirectAccess on AWS. If the domain infrastructure is hosted exclusively in AWS, provisioning clients can be performed using Offline Domain Join (ODJ). Provisioning DirectAccess clients using ODJ is only supported in Windows 8.x/10. Windows 7 clients cannot be provisioned using ODJ and must be joined to the domain using another form of remote network connectivity such as VPN.

Additional Resources

DirectAccess No Longer Supported in Microsoft Azure

Microsoft Server Software Support for Azure Virtual Machines

DirectAccess Network Location Server (NLS) Guidance

DirectAccess Network Location Server (NLS) Deployment Considerations for Large Enterprises

Provisioning DirectAccess Clients using Offline Domain Join (ODJ)

DirectAccess SSL Offload and IP-HTTPS Preauthentication with Citrix NetScaler

DirectAccess SSL Offload and IP-HTTPS Preauthentication with F5 BIG-IP

Planning and Implementing DirectAccess with Windows Server 2016 Video Training Course

Implementing DirectAccess with Windows Server 2016 Book

Planning and Implementing DirectAccess with Windows Server 2016 Video Training Course on Pluralsight

Planning and Implementing DirectAccess with Windows Server 2016I’m excited to announce my latest video training course, Planning and Implementing DirectAccess with Windows Server 2016, is now available on Pluralsight! In this course, I’ll provide a high-level overview of DirectAccess, compare it with VPN, and outline supporting infrastructure requirements. In addition, you’ll learn how to choose the best network topology for a DirectAccess deployment, how to prepare Active Directory and Public Key Infrastructure (PKI) for DirectAccess, and how to install and configure DirectAccess in Windows Server 2016 using the latest implementation and security best practices. You’ll also learn how to provision Windows 10 clients and understand the unique requirements for supporting Windows 7.

The course includes the following training modules:

Overview of DirectAccess
Planning for DirectAccess
Configuring DirectAccess with the Getting Started Wizard
Configuring DirectAccess with the Remote Access Setup Wizard
Provisioning DirectAccess Clients
Supporting Windows 7 Clients

Throughout the course, I share valuable knowledge and insight gained from more than 5 years of experience deploying DirectAccess for some of the largest organizations in the world. Pluralsight offers a free trial subscription if you don’t already have one, so watch my DirectAccess video training course today!

Additional Resources

Planning and Implementing DirectAccess with Windows Server 2016 on Pluralsight
Implementing DirectAccess with Windows Server 2016

Troubleshooting DirectAccess IP-HTTPS Error Code 0x90320

A Windows 7 or Windows 8.x/10 client may fail to establish a DirectAccess connection using the IP-HTTPS IPv6 transition technology. When troubleshooting this issue, running ipconfig.exe shows that the media state for the tunnel adapter iphttpsinterface is Media disconnected.

Troubleshooting DirectAccess IP-HTTPS Error Code 0x90320

Running the Get-NetIPHttpsState PowerShell command on Windows 8.x/10 clients or the netsh interface httpstunnel show interface command on Windows 7 clients returns an error code of 0x90320, with an interface status Failed to connect to the IPHTTPS server; waiting to reconnect.

Troubleshooting DirectAccess IP-HTTPS Error Code 0x90320

Error code 0x90320 translates to SEC_I_INCOMPLETE_CREDENTIALS, indicating the client was unable to authenticate to the DirectAccess server during the TLS handshake when establishing the IP-HTTPS IPv6 transition tunnel. This occurs when the DirectAccess server or an Application Delivery Controller (ADC) is configured to perform client certificate authentication for IP-HTTPS connections. The client may fail to authenticate if it does not have a valid certificate issued by the organization’s internal certification authority (CA) or if the DirectAccess server or ADC is configured to perform IP-HTTPS client authentication incorrectly.

To resolve this issue, ensure that a valid certificate is installed on the DirectAccess client. In addition, ensure that the DirectAccess server or ADC is configured to use the correct CA when authenticating clients establishing IP-HTTPS connections.

Additional Information

DirectAccess IP-HTTPS Preauthentication 

DirectAccess IP-HTTPS Preauthentication using Citrix NetScaler

DirectAccess SSL Offload and IP-HTTPS preauthentication using Citrix NetScaler 

DirectAccess IP-HTTPS preauthentication using F5 BIG-IP 

SSL Certificate Considerations for DirectAccess IP-HTTPS 

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/

Hotfix Available to Disable NRPT on Windows 8.x DirectAccess Clients

Updated April 9, 2015: The hotfix referred to in this article is now included in the November 2014 update rollup for Windows 8.1 and Windows Server 2012 R2. You will receive an error message when installing this update on Windows 8.x clients with the update rollup installed. More details here.

The Network Location Server (NLS) is a critical infrastructure component for DirectAccess deployments. The NLS is used by DirectAccess clients to determine if the client is located inside or outside of the corporate network. If the NLS becomes unavailable, DirectAccess clients that are already outside the corporate network are unaffected. However, DirectAccess clients that are inside the corporate network will mistakenly believe that they are outside and the Name Resolution Policy Table (NRPT) will be enabled, forcing name resolution requests for hosts in the internal namespace to be sent to the DNS64 service running on the DirectAccess server. If the DirectAccess server is unreachable from the internal network (a common scenario for a variety of reasons), DirectAccess clients inside the corporate network will be unable to connect to any local network resources by name until the NLS is once again reachable.

Configuring the Network Connectivity Assistant to Allow DirectAccess clients to use local name resolution does not resolve this issue. Although it sounds intuitive, it doesn’t resolve this specific issue where the NLS is unreachable.

Hotfix Available to Disable NRPT on Windows 8.x DirectAccess Clients

When the option to Allow DirectAccess clients to use local name resolution is enabled, the client can only choose to disconnect (use local name resolution) after it has successfully established a connection to the DirectAccess server. If the DirectAccess connection shows that it is still connecting, the option to disconnect is not available.

Hotfix Available to Disable NRPT on Windows 8.x DirectAccess Clients

To address this issue, Microsoft has released update KB2953212 for Windows 8.x clients that allows the disabling of the NRPT regardless if the client has successfully established a DirectAccess connection. With this update, if a DirectAccess client is located on the corporate network and is unable to reach the NLS, the user will be able to disable the NRPT (effectively disconnect DirectAccess) and once again connect to resources on the corporate network.
Hotfix Available to Disable NRPT on Windows 8.x DirectAccess Clients

This update is certainly no excuse not to deploy your NLS in a highly-available configuration using Windows Network Load Balancing (NLB) or a third-party external load balancer (hardware or software), but it can be a life-saver if your NLS becomes unavailable for any reason. I’d recommend deploying this update to all of your Windows 8.x DirectAccess clients soon.

For more information and to download the hotfix, click here.

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