DirectAccess and Always On VPN with Trusted Platform Module (TPM) Certificates

DirectAccess and Always On VPN with Trusted Platform Module (TPM) CertificatesTo enhance security when provisioning certificates for DirectAccess (computer) or Windows 10 Always On VPN (user) it is recommended that private keys be stored on a Trusted Platform Module (TPM) on the client device. A TPM is a dedicated security processor included in nearly all modern computers. It provides essential hardware protection to ensure the highest levels of integrity for digital certificates and is used to generate, store, and restrict the use of cryptographic keys. It also includes advanced security and protection features such as key isolation, non-exportability, and anti-hammering to prevent brute-force attacks.

To ensure that private keys are created and stored on a TPM, the certificate template must be configured to use the Microsoft Platform Crypto Provider. Follow the steps below to configure a certificate template required to use a TPM.

  1. Open the Certificate Templates management console (certtmpl.msc) and duplicate an existing certificate template. For example, if creating a certificate for DirectAccess, duplicate the Workstation Authentication certificate template. For Always On VPN, duplicate the User certificate template.
  2. On the Compatibility tab, ensure the Certification Authority and Certificate recipient compatibility settings are set to a minimum of Windows Server 2008 and Windows Vista/Server 2008, respectively.DirectAccess and Always On VPN with Trusted Platform Module (TPM) Certificates
  3. Select the Cryptography tab.
  4. Choose Key Storage Provider from the Provider Category drop down list.
  5. Choose the option Requests must use one of the following providers and select Microsoft Platform Crypto Provider.DirectAccess and Always On VPN with Trusted Platform Module (TPM) Certificates

Note: If Microsoft Platform Crypto Provider does not appear in the list above, got to the Request Handling tab and uncheck the option Allow private key to be exported.

Complete the remaining certificate configuration tasks (template display name, subject name, security settings, etc.) and publish the certificate template. Client machines configured to use this template will now have a certificate with private key fully protected by the TPM.

Additional Resources

Trusted Platform Module (TPM) Fundamentals

DirectAccess and Always On VPN Certificate Auto Enrollment

Deploying NetMotion Mobility in Azure

NetMotion MobilityOne of the many advantages NetMotion Mobility offers is that it requires no proprietary hardware to deliver its advanced capabilities and performance. It is a software solution that can be installed on any physical or virtual Windows server. This provides great deployment flexibility by allowing administrators to deploy this remote access solution on their existing virtual infrastructure, which is much less costly than investing in dedicated hardware or virtual appliances.

Cloud Deployment

As customers begin moving their traditional on-premises infrastructure to the cloud, it’s good to know that NetMotion Mobility is fully supported in popular public cloud platforms such as Microsoft Azure. Installing and configuring Mobility on a server in Azure requires a few important changes to a standard Azure VM deployment however. Below is detailed guidance for installing and configuring NetMotion Mobility on a Windows Server 2016 virtual machine hosted in the Microsoft Azure public cloud.

Azure Networking Configuration

Before installing the NetMotion Mobility software, follow the steps below to configure the Azure VM with a static public IP address and enable IP forwarding on the internal network interface.

  1. In the Azure management portal, select the NetMotion Mobility virtual machine and click Networking.
  2. Click on the public-facing network interface.
  3. In the Settings section click IP configurations.
  4. In the IP configurations section click on the IP configuration for the network interface.
  5. In the Public IP address setting section click Enabled for the Public IP address.
  6. Click Configure required settings for the IP address.
  7. Click Create New.
  8. Enter a descriptive name and select Static as the assignment method.
    Deploying NetMotion Mobility in Azure
  9. Click OK
  10. Click Save.Deploying NetMotion Mobility in AzureNote: The process of saving the network interface configuration takes a few minutes. Be patient!
  11. Note the public IP address, as this will be used later during the Mobility configuration.
  12. Close the IP address configuration blade.
  13. In the IP forwarding settings section click Enabled for IP forwarding.Deploying NetMotion Mobility in Azure
  14. Click Save.

NetMotion Mobility Installation

Proceed with the installation of NetMotion Mobility. When prompted for the external address, enter the public IP address created previously.

Deploying NetMotion Mobility in Azure

Next choose the option to Use pool of virtual IP addresses. Click Add and enter the starting and ending IP addresses, subnet prefix length, and default gateway and click OK.

Deploying NetMotion Mobility in Azure

Complete the remaining NetMotion Mobility configuration as required.

Azure Routing Table

A user defined routing table must be configured to ensure that NetMotion Mobility client traffic is routed correctly in Azure. Follow the steps below to complete the configuration.

  1. In the Azure management portal click New.
  2. In the Search the Marketplace field enter route table.
  3. In the results section click Route table.
  4. Click Create.
  5. Enter a descriptive name and select a subscription, resource group, and location.
  6. Click Create.

Deploying NetMotion Mobility in Azure

Once the deployment has completed successfully, click Go to resource in the notifications list.

Deploying NetMotion Mobility in Azure

Follow the steps below to add a route to the route table.

  1. In the Settings sections click Routes.
  2. Click Add.
  3. Enter a descriptive name.
  4. In the Address prefix field enter the subnet used by mobility clients defined earlier.
  5. Select Virtual appliance as the Next hop type.
  6. Enter the IP address of the NetMotion Mobility server’s internal network interface.
  7. Click OK.Deploying NetMotion Mobility in Azure
  8. Click Subnets.
  9. Click Associate.
  10. Click Choose a virtual network and select the network where the NetMotion Mobility gateway resides.
  11. Click Choose a subnet and select the subnet where the NetMotion Mobility gateway’s internal network interface resides.
  12. Click OK.

Note: If clients connecting to the NetMotion Mobility server need to access resources on-premises via a site-to-site gateway, be sure to associate the route table with the Azure gateway subnet.

Azure Network Security Group

A network security group must be configured to allow inbound UDP port 5008 to allow external clients to reach the NetMotion Mobility gateway server. Follow the steps below to create and assign a network security group.

  1. In the Azure management portal click New.
  2. In the Search the Marketplace field enter network security group.
  3. In the results section click Network security group.
  4. Click Create.
  5. Enter a descriptive name and select a subscription, resource group, and location.
  6. Click Create.

Deploying NetMotion Mobility in Azure

Once the deployment has completed successfully, click Go to resource in the notifications list.

Deploying NetMotion Mobility in Azure

Follow the steps below to configure the network security group.

  1. In the Settings section click Inbound security rules.
  2. Click Add.
  3. Enter 5008 in the Destination port ranges field.
  4. Select UDP for the protocol.
  5. Select Allow for the action.
  6. Enter a descriptive name.
  7. Click OK.
    Deploying NetMotion Mobility in Azure
  8. Click Network Interfaces.
  9. Click Associate.
  10. Select the external network interface of the NetMotion Mobility gateway server.

Summary

After completing the steps above, install the client software and configure it to use the static public IP address created previously. Alternatively, configure a DNS record to point to the public IP address and specify the Fully Qualified Domain Name (FQDN) instead of the IP address itself.

Additional Resources

Enabling Secure Remote Administration for the NetMotion Mobility Console

NetMotion Mobility Device Tunnel Configuration

NetMotion Mobility as an Alternative to Microsoft DirectAccess

NetMotion Mobility and Microsoft DirectAccess Comparison Whitepaper

NetMotion and Microsoft DirectAccess On-Demand Webinar

What is the Difference Between DirectAccess and Always On VPN?

Always On VPN Device Tunnel Configuration Guidance Now AvailableDirectAccess has been around for many years, and with Microsoft now moving in the direction of Always On VPN, I’m often asked “What’s the difference between DirectAccess and Always On VPN?” Fundamentally they both provide seamless and transparent, always on remote access. However, Always On VPN has a number of advantages over DirectAccess in terms of security, authentication and management, performance, and supportability.

Security

DirectAccess provides full network connectivity when a client is connected remotely. It lacks any native features to control access on a granular basis. It is possible to restrict access to internal resources by placing a firewall between the DirectAccess server and the LAN, but the policy would apply to all connected clients.

Windows 10 Always On VPN includes support for granular traffic filtering. Where DirectAccess provides access to all internal resources when connected, Always On VPN allows administrators to restrict client access to internal resources in a variety of ways. In addition, traffic filter policies can be applied on a per-user or group basis. For example, users in accounting can be granted access only to their department servers. The same could be done for HR, finance, IT, and others.

Authentication and Management

DirectAccess includes support for strong user authentication with smart cards and one-time password (OTP) solutions. However, there is no provision to grant access based on device configuration or health, as that feature was removed in Windows Server 2016 and Windows 10. In addition, DirectAccess requires that clients and servers be joined to a domain, as all configuration settings are managed using Active Directory group policy.

Windows 10 Always On VPN includes support for modern authentication and management, which results in better overall security. Always On VPN clients can be joined to an Azure Active Directory and conditional access can also be enabled. Modern authentication support using Azure MFA and Windows Hello for Business is also supported. Always On VPN is managed using Mobile Device Management (MDM) solutions such as Microsoft Intune.

Performance

DirectAccess uses IPsec with IPv6, which must be encapsulated in TLS to be routed over the public IPv4 Internet. IPv6 traffic is then translated to IPv4 on the DirectAccess server. DirectAccess performance is often acceptable when clients have reliable, high quality Internet connections. However, if connection quality is fair to poor, the high protocol overhead of DirectAccess with its multiple layers of encapsulation and translation often yields poor performance.

The protocol of choice for Windows 10 Always On VPN deployments is IKEv2. It offers the best security and performance when compared to TLS-based protocols. In addition, Always On VPN does not rely exclusively on IPv6 as DirectAccess does. This reduces the many layers of encapsulation and eliminates the need for complex IPv6 transition and translation technologies, further improving performance over DirectAccess.

Supportability

DirectAccess is a Microsoft-proprietary solution that must be deployed using Windows Server and Active Directory. It also requires a Network Location Server (NLS) for clients to determine if they are inside or outside the network. NLS availability is crucial and ensuring that it is always reachable by internal clients can pose challenges, especially in very large organizations.

Windows 10 Always On VPN supporting infrastructure is much less complex than DirectAccess. There’s no requirement for a NLS, which means fewer servers to provision, manage, and monitor. In addition, Always On VPN is completely infrastructure independent and can be deployed using third-party VPN servers such as Cisco, Checkpoint, SonicWALL, Palo Alto, and more.

Summary

Windows 10 Always On VPN is the way of the future. It provides better overall security than DirectAccess, it performs better, and it is easier to manage and support.

Here’s a quick summary of some important aspects of VPN, DirectAccess, and Windows 10 Always On VPN.

Traditional VPN DirectAccess Always On VPN
Seamless and Transparent No Yes Yes
Automatic Connection Options None Always on Always on, app triggered
Protocol Support IPv4 and IPv6 IPv6 Only IPv4 and IPv6
Traffic Filtering No No Yes
Azure AD Integration No No Yes
Modern Management Yes No (group policy only) Yes (MDM)
Clients must be domain-joined? No Yes No
Requires Microsoft Infrastructure No Yes No
Supports Windows 7 Yes Yes Windows 10 only

Always On VPN Hands-On Training

If you are interested in learning more about Windows 10 Always On VPN, consider registering for one of my hands-on training classes. More details here.

Additional Resources

Always On VPN and the Future of Microsoft DirectAccess

5 Important Things DirectAccess Administrators Should Know about Windows 10 Always On VPN

3 Important Advantages of Windows 10 Always On VPN over DirectAccess

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

Always On VPN Protocol Recommendations for Windows Server Routing and Remote Access Service (RRAS)Windows 10 Always On VPN is infrastructure independent and can be implemented using third-party VPN devices. It is not necessary to deploy any Windows servers at all to support an Always On VPN solution. However, in a recent blog post I outlined some compelling reasons to consider using Windows Server 2016’s Routing and Remote Access Service (RRAS) feature to terminate VPN connections. RRAS supports both modern and legacy VPN protocols, each with their own advantages and disadvantages. The choice of which protocols to support will be determined by many factors, but it is important to understand the capabilities of each to make an informed decision.

RRAS VPN Protocols

Windows RRAS supports the following VPN protocols.

  • Internet Key Exchange version 2 (IKEv2) – RFC7296
  • Secure Sockets Tunneling Protocol (SSTP) – Microsoft
  • Layer Two Tunneling Protocol over IPsec (L2TP/IPsec) – RFC2661
  • Point-to-Point Tunneling Protocol (PPTP) – RFC2637

There are pros and cons associated with each of these VPN protocols. Here’s a breakdown of each.

IKEv2

This IPsec-based VPN protocol is the preferred choice for most deployments. IKEv2 provides the best security and performance, with native features that enhance mobility. This latest version of IKE (v2) features streamlined messaging during connection establishment and enhanced session management that reduce protocol overhead and improve performance.

Advantages: Best security and performance.
Disadvantages: Firewalls may block required UDP ports.

SSTP

SSTP is an excellent alternative to IKEv2. It uses industry standard Transport Layer Security (TLS), making it widely accessible from most locations. It provides good security out of the box, but can be improved upon with additional configuration. SSTP lends itself well to load balancing, making it much easier to scale out than IKEv2. Optionally, TLS can be offloaded to an Application Delivery Controller (ADC) to reduce resource utilization on the RRAS server and further improve performance.

Advantages: Easy to configure with firewall friendly access.
Disadvantages: Not as secure IKEv2.

L2TP

While technically supported for Always On VPN, L2TP is a legacy VPN protocol that offers no real advantages over IKEv2. Its use is unnecessary and should be avoided.

Advantages: None.
Disadvantages: Firewalls may block required UDP ports.

PPTP

PPTP is considered an obsolete VPN protocol with many known security vulnerabilities. Its use should be avoided at all costs.

Advantages: None.
Disadvantages: Insecure.

Summary

Implementation best practices dictate that IKEv2 and SSTP be enabled to support Windows 10 Always On VPN connections when using Windows Server 2016 RRAS. The use of L2TP/IPsec and PPTP should be avoided. The combination of IKEv2 and SSTP will provide the best security and availability for remote workers. Clients that can establish IKEv2 VPN connections can take advantages of the security and performance benefits it provides. SSTP can be enabled as a fallback for clients that are unable to establish an IKEv2 connection due to restricted firewall access.

Always On VPN Hands-On Training

Interested in learning more about Windows 10 Always On VPN? Hands-on training classes are now forming. More details here.

Additional Resources

Frequently Asked Questions about Microsoft’s PPTP Implementation

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

Windows 10 Always On VPN and the Future of DirectAccess 

5 Things DirectAccess Administrators Should Know about Always On VPN 

3 Important Advantages of Windows 10 Always On VPN over DirectAccess 

Windows 10 Always On VPN Hands-On Training Classes

Always On VPN Device Tunnel Configuration Guidance Now Available

Always On VPN Device Tunnel Configuration Guidance Now AvailableWindows 10 Always On VPN hands-on training classes now forming. Details here.

When Always On VPN is configured for Windows 10, the VPN connection is established automatically when the user logs on to their device. This differs fundamentally from DirectAccess, where the connection is established by the machine, before the user logs on. This subtle but important difference has some important ramifications. For example, it means that a user cannot use Always On VPN until they’ve logged on to their device at least once while connected to the corporate network. DirectAccess doesn’t have this limitation, as a connection to an on-premises domain controller is available to authenticate a new user upon first logon.

Device Tunnel Support

To address this shortcoming with Always On VPN, and to provide better feature parity with DirectAccess, Microsoft introduced an update to Windows 10 in the recent Fall Creators update (v1709) that allows for the configuration of a device tunnel for Windows 10 Always On VPN. Once enabled, the device itself can automatically establish a secure remote connection before the user logs on. This enables scenarios such as device provisioning for new remote users without cached credentials. It also enables support for password reset using CTRL+ALT+DEL.

Manage Out

Device tunnel for Windows 10 Always On VPN also enables important manage out scenarios that DirectAccess administrators have come to rely upon. With a device tunnel configured, administrators can initiate connections to remote connected Always On VPN clients to provide remote management and support, without requiring a user to be logged on at the time.

Requirements

To support an Always On VPN device tunnel, the client must be running Windows 10 Enterprise or Education v1709 or later. The computer must be domain-joined and have a machine certificate installed. Device tunnel can only be configured using the built-in Windows 10 VPN client (no support for third-party clients) and the IKEv2 protocol must be used.

Caveat

When configuring a device tunnel, traffic filters can be implemented to restrict communication to only those internal resources required, such as domain controllers, Windows Server Update Services (WSUS) or System Center Configuration Manager (SCCM) servers. However, when traffic filters are used, no inbound traffic to the client is allowed. If manage out is required over the device tunnel, traffic filters cannot be configured. Microsoft expects to remove this limitation in a future update.

Provisioning and Documentation

Configuring and provisioning a Windows 10 Always On VPN device tunnel is similar to the process for the Always On VPN connection itself. A VPN profileXML file is created and then deployed via a Mobile Device Management (MDM) solution such as Microsoft Intune. Optionally, the VPN profileXML can be deployed using SCCM or PowerShell. Additional information about Windows 10 Always On VPN device tunnel configuration, including a sample profileXML and PowerShell script, can be found here.

Additional Resources

Configure a VPN Device Tunnel in Windows 10

Always On VPN and the Future of DirectAccess

5 Things DirectAccess Administrators Should Know about Always On VPN

PowerShell Recommended Reading for DirectAccess and Always On VPN Administrators

PowerShell Recommended Reading for DirectAccess and Always On VPN AdministratorsPowerShell is an important skill for administrators supporting Microsoft workloads including DirectAccess and Always On VPN. Using PowerShell to install required roles and features is much simpler and quicker than using the Graphical User Interface (GUI), with only a single command required to accomplish this task. Some settings aren’t exposed in the GUI and can only be configured using PowerShell. In addition, PowerShell makes the task of troubleshooting DirectAccess and Always On VPN much easier.

Learn PowerShell

One of the best resources for learning PowerShell is the book Learn PowerShell in a Month of Lunches authored by Microsoft MVPs and recognized PowerShell experts Don Jones and Jeff Hicks. This book, now in its third edition, should be considered essential reading for all Microsoft administrators. Click here for more details.

PowerShell Recommended Reading for DirectAccess and Always On VPN Administrators

Learn PowerShell Scripting

Recently Don and Jeff released a new book entitled Learn PowerShell Scripting in a Month of Lunches. This new book builds upon the skills learned in their first title by focusing on the development of PowerShell scripts to automate many common administrative tasks. PowerShell scripts can also be used to build custom, reusable tools to more effectively manage and monitor Microsoft workloads. Click here for more details.

PowerShell Recommended Reading for DirectAccess and Always On VPN Administrators

PowerShell for the Future

In my experience, far too many administrators today lack crucial PowerShell abilities. Don’t get left behind! PowerShell is rapidly becoming a required skill, so get these books and start learning PowerShell today!

Additional Resources

Top 5 DirectAccess Troubleshooting PowerShell Commands

Configure Windows Server Core to use PowerShell by Default

 

Microsoft Ignite Conference 2017

Will you be attending the Microsoft Ignite conference in Orlando, FL next week? Let’s connect! I’m not giving any talks this year, so I will be spending most of my time with the folks at Pointsharp in their booth in the expo hall. Want to talk security, remote access, multifactor authentication, load balancing/application delivery, PKI, or anything else? Stop by and say hi! Follow me on Twitter @richardhicks for live updates. In addition, I’ll be hosting a happy hour event with NetMotion on Tuesday, September 26 at 6PM at the Rocks lounge in the Hyatt Regency hotel just across the street from the conference center. Be sure to drop in and say hello! Hope to see you there!

Microsoft Ignite 2017

NetMotion Mobility as an Alternative to DirectAccess

Learn more about NetMotion Mobility by registering for my free live webinar here!

NetMotion Mobility as an Alternative to DirectAccessAs I outlined in a recent blog post, there has been much speculation surrounding the end of life for Microsoft DirectAccess. This is not surprising, as Microsoft has not made any investments in DirectAccess since the introduction of Windows Server 2012. Recently, Microsoft began promoting its Always On VPN solution as an alternative for DirectAccess. While DirectAccess has not been formally deprecated, Microsoft is actively encouraging organizations considering DirectAccess to deploy Always On VPN instead, as indicated here.

NetMotion Mobility as an Alternative to Microsoft DirectAccess

Source: https://docs.microsoft.com/en-us/windows-server/remote/remote-access/vpn/vpn-top#advanced-vpn-connectivity

DirectAccess Alternatives

It’s important to state that, at the time of this writing, DirectAccess is still fully supported in Windows 10 and Windows Server 2016 and will be for quite some time. However, the future for DirectAccess is definitely limited, and customers should start considering alternative remote access solutions.

Always On VPN

Microsoft is positioning Always On VPN as the replacement for DirectAccess. Always On VPN offers some important new capabilities missing from DirectAccess. For example, Always On VPN supports all Windows 10 client SKUs, not just Enterprise and Education as DirectAccess does. Always On VPN includes important security enhancements such as conditional access with system health checks, access control list (ACL) enforcement per device and per application, and more.

Always On VPN Limitations

But Always On VPN has some serious limitations too. For example, Always On VPN works only with Windows 10. Windows 7 is not supported at all. Managing and supporting Always On VPN has its own challenges. It cannot be managed using Active Directory and group policy in the traditional way. You must use System Center Configuration Manager (SCCM), Intune, or PowerShell to configure and manage VPN clients.

NetMotion Mobility

I’m excited to announce I’ve recently partnered with NetMotion to provide their secure remote access solutions to organizations looking for alternatives to DirectAccess and Always On VPN. NetMotion Mobility provides the same seamless and transparent, always on remote access with some additional important features not included in DirectAccess and Always On VPN.

Broad Client Support – NetMotion Mobility can provide DirectAccess-like remote access for all versions and SKUs of Windows as well as Mac, iOS (iPhone and iPad), and Android.

Enhanced Security – NetMotion Mobility includes fine-grained policy enforcement to restrict network access based on a wide range of parameters including IP address, protocol, port, application, time of day, location, and type of network (e.g. wired, Wi-Fi, wireless, etc.). NetMotion Mobility also includes integrated Network Access Control (NAC) to validate device configuration prior to connecting, ensuring the highest level of security for remote endpoints. More details here and here.

Improved Performance – NetMotion Mobility client to server communication is optimized to improve reliability and performance. Network traffic is compressed and prioritized to ensure optimum performance for critical applications. Session persistence allows mobile workers to remain connected during times of poor connectivity or when roaming between different networks. More details here.

Greater Visibility – NetMotion Mobility provides a wealth of detailed information to perform analysis and troubleshooting for remote connections. Performance and diagnostic information is logged in real-time and provides administrators with crucial data and insight to quickly identify and resolve connectivity issues. More details here.

Better Supportability – NetMotion Mobility is supported by dedicated, highly trained support engineers with deep product experience. NetMotion support is not tiered. The support engineer who answers the phone will handle the case until resolution.

Learn More about NetMotion

NetMotion Mobility is a truly comprehensive remote access solution and an excellent alternative to DirectAccess. To learn more about NetMotion Mobility and to see it in action, fill out the form below and I’ll get in touch with you. You can also register for my upcoming free live webinar here.

Additional Information

Webinar: Comparing DirectAccess and NetMotion Mobility

Always On VPN and the Future of DirectAccess

NetMotion and DirectAccess Comparison Whitepaper

NetMotion and Skype for Business demonstration video

NetMotion Website

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

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/

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