Configure Kemp LoadMaster for DirectAccess NLS

In a previous post I outlined how to configure the F5 BIG-IP Local Traffic Manager (LTM) to serve as the Network Location Server (NLS) for a DirectAccess deployment. Many people then asked if it was possible to do the same with the Kemp Technologies LoadMaster load balancing solution. Until now, it was not. However, beginning with release 7.1-28b it is!

After upgrading your Kemp LoadMaster to version 7.1-28b, open the LoadMaster management console, expand Virtual Services, and then click Add New. Specify a Virtual Address, enter 443 for the Port, optionally provide a descriptive Service Name, select TCP for the Protocol, and then click Add this Virtual Service.

Configure Kemp LoadMaster for DirectAccess NLS

Expand SSL Properties and select Enabled for SSL Acceleration. If you have not yet installed the SSL certificate for the NLS, you will be prompted to use a temporary certificate.

Configure Kemp LoadMaster for DirectAccess NLS

Expand Advanced Properties and select 200 OK from the Error Code drop-down list. Optionally you can enter a description for the service in the Error Message box and click Set Message. This will be displayed if someone opens the NLS web site in a web browser.

Configure Kemp LoadMaster for DirectAccess NLS

At the top of the page click Back. If the SSL certificate for the NLS was not previously installed, add it now by clicking Add New.

Configure Kemp LoadMaster for DirectAccess NLS

Click Import Certificate and provide the certificate file as required. Once the certificate is installed successfully, assign the certificate to the NLS virtual service and click Save Changes.

Configure Kemp LoadMaster for DirectAccess NLS

Once complete, update the DNS record for NLS to point to the IP address assigned to the virtual service running on the LoadMaster.

For more information about the Kemp Technologies LoadMaster load balancer and to download a free fully-functional trial, click here. You can also download a completely free and fully-functional version of the Kemp LoadMaster here.

To learn more about the DirectAccess NLS, please refer to the following posts:

DirectAccess Network Location Server Guidance

DirectAccess NLS Deployment Considerations for Large Enterprises

Configuring Multiple Windows Server 2012 R2 DirectAccess Instances

DirectAccess in Windows Server 2012 R2 supports many different deployment configurations. It can be deployed with a single server, multiple servers in a single location, multiple servers in multiple locations, edge facing, in a perimeter or DMZ network, etc.

Global Settings

There are a number of important DirectAccess settings that are global in scope and apply to all DirectAccess clients, such as certificate authentication, force tunneling, one-time password, and many more. For example, if you configure DirectAccess to use Kerberos Proxy instead of certificates for authentication, Windows 7 clients are not supported. In this scenario it is advantageous to have a second parallel DirectAccess deployment configured specifically for Windows 7 clients. This allows Windows 8 clients to take advantage of the performance gains afforded by Kerberos Proxy, while at the same time providing an avenue of support for Windows 7 clients.

Parallel Deployments

To the surprise of many, it is indeed possible to deploy DirectAccess more than once in an organization. I’ve been helping customers deploy DirectAccess for nearly five years now, and I’ve done this on more than a few occasions. In fact, there are some additional important uses cases that having more than one DirectAccess deployment can address.

Common Use Cases

QA and Testing – Having a separate DirectAccess deployment to perform testing and quality assurance can be quite helpful. Here you can validate configuration changes and verify updates without potential negative impact on the production deployment.

Delegated Administration – DirectAccess provides support for geographic redundancy, allowing administrators to create DirectAccess entry points in many different locations. DirectAccess in Windows Server 2012 R2 lacks support for delegated administration though, and in some cases it may make more sense to have multiple separate deployments as opposed to a single, multisite deployment. For example, many organizations are divided in to different business units internally and may operate autonomously. They may also have different configuration requirements, which can be better addressed using individual DirectAccess implementations.

Migration – If you have currently deployed DirectAccess using Windows Server 2008 R2 with or without Forefront UAG 2010, migrating to Windows Server 2012 R2 can be challenging because a direct, in-place upgrade is not supported. You can, however, deploy DirectAccess using Windows Server 2012 R2 in parallel to your existing deployment and simply migrate users to the new solution by moving the DirectAccess client computer accounts to a new security group assigned to the new deployment.

Major Configuration Changes – This strategy is also useful for scenarios where implementing changes to the DirectAccess configuration would be disruptive for remote users. For example, changing from a single site to a multisite configuration would typically require that all DirectAccess clients be on the LAN or connect remotely out-of-band to receive group policy settings changes after multisite is first configured. In addition, parallel deployments can significantly ease the pain of transitioning to a new root CA if required.

Unique Client Requirements – Having a separate deployment may be required to take advantage of the unique capabilities of each client operating system. For example, Windows 10 clients do not support Microsoft Network Access Protection (NAP) integration. NAP is a global setting in DirectAccess and applies to all clients. If you still require NAP integration and endpoint validation using NAP for Windows 7 and Windows 8.x, another DirectAccess deployment will be required to support Windows 10 clients.

Requirements

To support multiple Windows Server 2012 R2 DirectAccess deployments in the same organization, the following is required:

Unique IP Addresses – It probably goes without saying, but each DirectAccess deployment must have unique internal and external IPv4 addresses.

Distinct Public Hostname – The public hostname used for each deployment must also be unique. Multi-SAN certificates have limited support for DirectAccess IP-HTTPS (public hostname must be the first entry in the list), so consider using a wildcard certificate or obtain certificates individually for each deployment.

Group Policy Objects – You must use unique Active Directory Group Policy Objects (GPOs) to support multiple DirectAccess deployments in a single organization. You have the option to specify a unique GPO when you configure DirectAccess for the first time by clicking the Change link next to GPO Settings on the Remote Access Review screen.

Configuring Multiple Windows Server 2012 R2 DirectAccess Instances

Enter a distinct name for both the client and server GPOs. Click Ok and then click Apply to apply the DirectAccess settings for this deployment.

Configuring Multiple Windows Server 2012 R2 DirectAccess Instances

Note: It is not possible to change the names of DirectAccess GPOs after initial configuration is complete. The only way to change GPO names after DirectAccess has been configured the first time is to remove the configuration completely and start over.

Windows 7 DirectAccess Connectivity Assistant (DCA) GPOs – If the DirectAccess Connectivity Assistant (DCA) v2.0 has been deployed for Windows 7 clients, separate GPOs containing the DCA client settings for each individual deployment will have to be configured. Each DirectAccess deployment will have unique Dynamic Tunnel Endpoint (DTE) IPv6 addresses which are used by the DCA to confirm corporate network connectivity. The rest of the DCA settings can be the same, if desired.

Supporting Infrastructure

The rest of the supporting infrastructure (AD DS, PKI, NLS, etc.) can be shared between the individual DirectAccess deployments without issue. Once you’ve deployed multiple DirectAccess deployments, make sure that DirectAccess clients DO NOT belong to more than one DirectAccess client security group to prevent connectivity issues.

Summary

DirectAccess with Windows Server 2012 R2 supports many different deployment models. For a given DirectAccess deployment model, some settings are global in scope and may not provide the flexibility required by some organizations. To address these challenges, consider a parallel deployment of DirectAccess. This will enable you to take advantage of the unique capabilities of each client operating system, or allow you to meet the often disparate configuration requirements that a single deployment cannot support.

DirectAccess and Windows 10 Better Together

With last week’s release of Windows 10, many organizations who chose to skip Windows 8 are now beginning to deploy Windows 10. To maximize investment in Windows 10, DirectAccess can be leveraged to provide employees with seamless and transparent, always on, secure remote corporate network connectivity. DirectAccess has been around for many years, and today the most popular DirectAccess client is Windows 7. However, Windows 10 provides better support for DirectAccess features that enhance performance and availability, while at the same making it easier to implement and support. Windows 10 opens up many new and compelling deployment scenarios for small businesses to large scale enterprises.

Full Support for Geographic Redundancy

Without a doubt the most important DirectAccess feature Windows 10 supports is automatic entry point selection and transparent failover for multisite deployments. DirectAccess multisite deployment provides essential geographic redundancy for organizations with multiple physical locations. Windows 7 has only minimal support for multisite deployment, with clients required to be assigned to a single entry point. Windows 10 clients are aware of all entry points and will intelligently select the closest entry point when establishing a DirectAccess connection. If the entry point becomes unavailable during the connection, Windows 10 clients will transparently connect to another entry point automatically.

Better Scalability and Performance

Windows 10, like Windows 8 before it, includes support for IP-HTTPS null encryption. This feature greatly improves scalability on the DirectAccess server by eliminating the needless double encryption that Windows 7 clients perform. This reduces resource consumption on the server and enables the server to support many more DirectAccess client connections.

DirectAccess and Windows 10 Better Together

Enhanced Supportability

Many will also appreciate Windows 10’s built-in DirectAccess connectivity status indicator. No longer will administrators have to deploy, manage, and maintain additional software to provide this essential functionality.

To access DirectAccess information in Windows 10, press Window Key + I, click Network & Internet, and then click the DirectAccess tab. Here you will find vital details about DirectAccess configuration and status such as connection state, currently connected entry point, and a site selection drop down box (if manual site selection is enabled by an administrator). In addition you can generate and collect log information for troubleshooting purposes.

DirectAccess and Windows 10 Better Together

Native PowerShell Support

Anyone tasked with troubleshooting DirectAccess configuration and connectivity issues will appreciate the native PowerShell integration with DirectAccess in Windows 10. With just a few commands a wealth of information about DirectAccess configuration and connectivity status can be obtained.

Need to quickly determine if a Windows 10 client has been provisioned for DirectAccess successfully?

Get-DAClientExperienceConfiguration

DirectAccess and Windows 10 Better Together

Has the Windows 10 client connected successfully? If not, why?

Get-DAConnectionStatus

DirectAccess and Windows 10 Better Together

Need to identify the Network Location Server (NLS) the client is configured to use?

Get-NCSIPolicyConfiguration

DirectAccess and Windows 10 Better Together

Looking for DirectAccess multisite entry point details and connection status?

Get-DAEntryPointTableItem

DirectAccess and Windows 10 Better Together

PKI Optional (But Recommended)

Finally, when Windows 10 (and Windows 8.x) clients are supported exclusively a Public Key Infrastructure (PKI) is optional. Here instead the Kerberos Proxy is leveraged to perform DirectAccess client authentication, which reduces infrastructure requirements by eliminating the need for a PKI. However, this configuration offers only limited support for DirectAccess features. For example, a PKI is still required if any Windows 7 clients are deployed. Also, PKI is required to support features such as one-time password (OTP) authentication, Microsoft Network Access Protection (NAP) integration, load balancing (integrated or external), force tunneling, and multisite configuration.

DirectAccess and Windows 10 Better Together

For optimum security and maximum deployment flexibility it is recommended that PKI be used to manage certificates for all DirectAccess deployments including those supporting only Windows 8.x and Windows 10 clients.

Summary

DirectAccess and Windows 10 are much better together. Windows 10 provides full support for the geographic load balancing features of DirectAccess and at the same time offers improved scalability and performance. Windows 10 also makes supporting and troubleshooting DirectAccess clients much easier. And for smaller deployments, Windows 10 can lower the barrier to entry for organizations considering DirectAccess by eliminating the need for a full PKI deployment.

DirectAccess Client and Server Settings GPOs Deleted

Microsoft Windows Server Active DirectoryFor DirectAccess deployments where domain controllers are running Windows Server 2003 or Windows Server 2003 R2 using the File Replication Service (FRS) for replication, DirectAccess client and server settings Group Policy Objects (GPOs) may be deleted. If these GPOs are deleted, DirectAccess connectivity will be disrupted. If the GPOs cannot be recovered via backup, it will be necessary to rebuild the entire DirectAccess deployment from scratch.

Microsoft recently updated their DirectAccess Unsupported Configurations documentation to reflect new guidance for DirectAccess deployments where the FRS is used for the distribution of Active Directory GPOs. DirectAccess is no longer supported in environments where FRS is used for SYSVOL replication.

What this means is that if you plan to deploy DirectAccess, domain controllers must be running Windows Server 2008 or later, and Distributed File System Replication (DFS-R) must be used for replication.

More details can be found here.

DirectAccess Consulting Services Now Available

Microsoft Certified Solutions Associate (MCSA)For the last five years I’ve been helping organizations large and small deploy DirectAccess. During that time I have amassed a wealth of knowledge and experience with this unique technology. DirectAccess is not trivial to install, configure, or troubleshoot. Also, it’s easy to make mistakes in the planning and design phase that can turn in to serious issues later in the deployment. To make matters worse, many organizations are deploying DirectAccess for the first time, and without essential guidance they are prone to making common mistakes or choosing configuration options that are less than optimal both in terms of supportability and performance.

Having deployed DirectAccess for some of the largest companies in the world, there isn’t much I haven’t already encountered. If you are looking for the best chance of success for your DirectAccess deployment, consider a consulting engagement with me. I can provide assistance with all facets of DirectAccess implementation including planning and design, installation, configuration, and troubleshooting. Consulting services at reasonable rates are available for all types of DirectAccess work including:

  • New DirectAccess installations
  • Migration from previous versions of DirectAccess
  • Upgrade or expansion of existing DirectAccess deployment
  • Enterprise planning and design for large-scale, multisite DirectAccess deployments
  • DirectAccess high availability (local and geographic)
  • Manage-out for DirectAccess with external hardware load balancers and/or multisite configuration
  • Multisite DirectAccess with geographic redundancy for Windows 7 clients
  • Existing DirectAccess design review and security assessment
  • Windows Server 2012 R2 client-based VPN configuration
  • DirectAccess client connectivity troubleshooting
  • DirectAccess training

These services and many more can be performed on-site or remotely. If you are interested in obtaining my services, drop me a note at rich@richardhicks.com for more details.

DirectAccess Single NIC Load Balancing with Kemp LoadMaster

Kemp Technologies Load BalancersEarlier this year I authored the Windows Server 2012 R2 DirectAccess Deployment Guide for Kemp LoadMaster load balancers. The documentation described in detail how to configure the Kemp LoadMaster to provide load balancing for DirectAccess when configured with two network adapters. It also assumed that the DirectAccess server is configured to use the LoadMaster as its default gateway.

There are many scenarios in which the DirectAccess server does not use the LoadMaster as its default gateway, most commonly deployments where the DirectAccess server is configured with a single NIC. To support load balancing for DirectAccess configured with a single NIC, it will be necessary to make some changes to the LoadMaster configuration to enable load balancing support for this scenario.

To configure the Kemp LoadMaster for load balancing DirectAccess single NIC deployments, follow the guidance to create the virtual service as documented. After creating the virtual service for DirectAccess, expand Standard Options, deselect Transparency, and then select Subnet Originating Requests.

DirectAccess Single NIC Load Balancing with Kemp LoadMaster

This will configure the LoadMaster to forward traffic to the DirectAccess server using the internal IP address of the LoadMaster as the source IP address for the connection instead of the original public address of the client. This allows the DirectAccess server to return DirectAccess traffic to the LoadMaster without having to use it as its default gateway.

DirectAccess DNS Records Explained

After installing and configuring DirectAccess with Windows Server 2012 R2, several new host records appear automatically in the internal DNS (assuming dynamic DNS is supported, of course). One of them is directaccess-corpConnectivityHost and the other is directaccess-WebProbeHost. These DirectAccess DNS entries are used by Windows 8 and later clients for connectivity checks at various stages of DirectAccess connection establishment.

DirectAccess DNS Records Explained

Figure 1 – DirectAccess DNS records for IPv4-only network.

DirectAccess DNS Records Explained

Figure 2 – DirectAccess DNS records for dual-stack IPv4/IPv6 network.

Here is a detailed description for each of these DirectAccess DNS entries.

directaccess-corpConnectivityHost – This DNS host record includes both A and AAAA records when deployed on IPv4-only networks. Its A host record resolves to 127.0.0.1, which is the IPv4 loopback address. Its AAAA host record resolves to an IPv6 address that is a combination of the DirectAccess NAT64 IPv6 prefix and 7F00:1 (the hexadecimal equivalent of 127.0.0.1). When DirectAccess is configured on a network with native IPv6, the directaccess-corpConnectivityHost DNS record will only include a single AAAA record resolving to ::1.

This host record is used by the DirectAccess client to determine if name resolution for the corporate namespace is working after the IPv6 transition tunnel (6to4, Teredo, or IP-HTTPS) has been established. It does this by attempting to resolve the hostname directaccess-corpConnectivityHost.<corp_fqdn> (e.g. directaccess-corpConnectivityHost.corp.example.net) to an IPv6 address that it expects (the organization’s NAT64 prefix + 7F00:1 or ::1). If it does not resolve, or resolves to a different address, the client will assume that the transition tunnel was not established successfully and, if possible, fall back to another IPv6 transition protocol and repeat the process until it is successful.

Note: The DirectAccess client does not attempt to connect to the IP address resolved by directaccess-corpConnectivityHost. It simply compares the IP address returned by the query to the expected address (NAT64 prefix + 7F00:1 or ::1).

directaccess-WebProbeHost – This DNS host record includes only A records and resolves to the IPv4 address assigned to the internal network interface of the DirectAccess server. If load balancing is enabled, this host record will resolve to the virtual IP address (VIP) of the array. For multisite deployments there will be directaccess-WebProbeHost A host records for each entry point in the organization.

This host record is used by the DirectAccess client to verify end-to-end corporate network connectivity over the DirectAccess connection. The client will attempt to connect to the directaccess-WebProbeHost URL using HTTP. If successful, the DirectAccess connectivity status indicator will show Connected.

If any of these DirectAccess DNS records are missing or incorrect, a number of issues may arise. If the directaccess-corpConnectivityHost host record is missing or incorrect, DirectAccess IPv6 transition tunnel establishment may fail. If the directaccess-WebProbeHost record is missing or incorrect, the DirectAccess connectivity status indicator will perpetually show Connecting. This commonly occurs when an external load balancer is used and a virtual server isn’t created for the web probe host port (TCP 80). In addition, these DirectAccess DNS entries are not static and may be deleted if DNS scavenging of stale resource records is enabled on the DNS server.

Provisioning DirectAccess Clients using Windows Offline Domain Join

DirectAccess on Microsoft WindowsOne of the many advantages DirectAccess has over traditional client-based VPN is the ease with which DirectAccess clients can be provisioned. DirectAccess does not require any special software to be installed on the client. Everything that DirectAccess needs is included as part of the operating system. This makes onboarding a client for DirectAccess is as simple as adding a computer account to the DirectAccess client security group in Active Directory. That’s it! As soon as the client restarts it will be configured for DirectAccess.

This process works great if the client computer is already joined to the domain and has access to the LAN (either directly connected or via client-based VPN). But what if the client is in a remote location and isn’t yet joined to the domain? Offline Domain Join (ODJ) can help. ODJ is a feature of the Windows operating system introduced with Windows 7 and Windows Server 2008 R2 that allows an administrator to join a host to the domain without requiring the host to contact a domain controller. Beginning with Windows 8 and Server 2012, ODJ supports new command-line parameters that allow the administrator to configure the client machine to include DirectAccess certificates and policies.

Note: ODJ will only provision DirectAccess certificates and policies for Windows 8.x and later clients. ODJ with Windows 7 clients is limited to joining the domain only. ODJ cannot provision Windows 7 clients for DirectAccess.

To use ODJ to provision a DirectAccess client, first create a computer account in Active Directory and then add the account to the DirectAccess client security group. Next, open an elevated Command Prompt window on the DirectAccess server and execute the following command.

djoin.exe /provision /machine <client_machine_name>
/domain <domain_name> /policynames
<DirectAccess_client_settings_ GPO_name>
/certtemplate <DirectAccess_certificate_template_name>
/savefile <filename> /reuse

For example:

djoin.exe /provision /machine client5
/domain lab.richardhicks.net
/policynames "DirectAccess Client Settings"
/certtemplate machine
/savefile c:\users\rhicks\desktop\provision.txt /reuse

Provisioning DirectAccess Clients using Windows Offline Domain Join

On the DirectAccess client, copy the ODJ provisioning file locally. Open an elevated Command Prompt window and execute the following command.

djoin.exe /requestodj /loadfile <filename>
/windowspath <Windows_directory> /localos

For example:

djoin.exe /requestodj /loadfile c:\users\setup\provision.txt
/windowspath C:\Windows /localos

Provisioning DirectAccess Clients using Windows Offline Domain Join

After a restart, the client will be joined to the domain and now be able to establish a DirectAccess connection to the corporate network. Users can now log on with their domain credentials.

DirectAccess and the Free Kemp Technologies LoadMaster

Kemp Technologies Load BalancersBeginning with Windows Server 2012, DirectAccess includes native support for external load balancers. Where high availability is required (which is most deployments!) the use of an external load balancer (physical or virtual) has many advantages over Windows Network Load Balancing (NLB).

While NLB is easy to configure, it is not without serious drawbacks. NLB relies on network broadcasts, which limits its effectiveness in some environments. In addition, NLB supports only a single load distribution mode, which is round robin. NLB also lacks a convenient monitoring interface.

A dedicated load balancing solution provides more robust load balancing and better, more granular traffic control than NLB. Along with this greater control comes increased traffic visibility, with most solutions providing details and insight in to node health, status, and performance. Many solutions also offer Global Server Load Balancing (GSLB) support, which enhances geographic redundancy and offers improvements when performing automatic site selection in multisite deployments.

Often the barrier to adoption for a dedicated external load balancer is cost. Many of the leading solutions are incredibly powerful and feature-rich, but come with a substantial price tag. The Kemp Technologies LoadMaster Load Balancers solution is an excellent, cost-effective alternative and works quite well providing load balancing support for DirectAccess. And to make things even more interesting, they recently announced a completely FREE version of their commercial load balancing product.

The Free Kemp Technologies LoadMaster Load Balancer is fully functional and supported for use in production environments. It provides full layer 4-7 support and includes reverse proxy, edge security, web application firewall (WAF) functionality, and GSLB. It can be installed on most major virtualization platforms including Microsoft Hyper-V, VMware, and more. The free LoadMaster is also available in Kemp Technologies LoadMaster Load Balancer on the Microsoft Azure Public Cloud Platform, as well as the VMware and Amazon public cloud platforms.

The free LoadMaster does have some restrictions, however. For example, you cannot create high availability clusters of LoadMasters. Also, the free LoadMaster is limited in terms of network throughput (20Mbps) and SSL/TLS transaction per second (50, using 2048 bit keys). There is also a limit on the number of virtual servers you can create (1000). The free LoadMaster must also have access to the Internet as it must be able to call home to validate its license every 30 days. You can find a complete model comparison matrix between the free and commercial Kemp LoadMasters Kemp LoadMaster Comparison Chart.

As the free version of the Kemp LoadMaster does not support clustering, technically you still have a single point of failure. However, it can still deliver a net improvement in stability and uptime, as the LoadMaster is a purpose-built platform that requires much less servicing and maintenance than a typical Windows server.

DirectAccess Deployment Guide for Kemp LoadMaster Load BalancersFor detailed information about configuring the Kemp LoadMaster to provide load balancing services for DirectAccess, be sure to download the DirectAccess Deployment Guide for Kemp LoadMaster Load Balancers. And if you end up liking the free Kemp LoadMaster load balancer (and I’m confident you will!) you can always upgrade to the full commercial release at any time.

For more information about the free Kemp LoadMaster load balancer, click Free Kemp LoadMaster Load Balancer.

DirectAccess and the TLS Logjam Attack

Another critical flaw affecting Transport Layer Security (TLS) was discovered recently that could put some organizations at risk. The “Logjam” attack exploits a weakness in how the Diffie-Hellman key exchange is used. An attacker, acting as a man-in-the-middle, can potentially force a downgrade of the TLS connection, resulting in the use of weak cryptography. The Qualys SSL Labs SSL Server Test has been updated to identify this vulnerability. When testing a DirectAccess server you will receive the following warning message.

“This server supports weak Diffie-Hellman (DH) key exchange parameters. Grade capped to B.”

DirectAccess and the Logjam Attack

DirectAccess leverages SSL and TLS as part of the IP-HTTPS IPv6 transition protocol, which is used to tunnel IPv6 packets over the IPv4 Internet. These IPv6 packets are encrypted using IPsec. If an attacker were to break the SSL/TLS connection they would gain nothing. Because of this, a dedicated DirectAccess server is unaffected by the Logjam attack. Mitigating it would provide no additional protection, so you can safely ignore the warning about weak DH key exchange parameters being supported.

However, if DirectAccess has been configured to use one-time password (OTP) authentication, the client-based VPN role has been enabled and configured, or the Web Application Proxy (WAP) role has been installed on the DirectAccess server, then the Logjam attack represents a serious risk and should be mitigated. Also, in some cases it may be desirable to make this change on a dedicated DirectAccess server just to prevent an audit finding and avoid having to explain why the DirectAccess workload would be unaffected by this attack.

To mitigate this vulnerability it will be necessary to remove support for cipher suites that use the Diffie-Hellman key exchange protocol on the DirectAccess server. This is accomplished by opening the Local Group Policy Editor (gpedit.msc) on the DirectAccess server and expanding Computer Configuration, Administrative Templates, and Network. Select SSL Configuration Settings and then double-click SSL Cipher Suite Order. Select Enabled and then replace the default list of cipher suites with the following list.

TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384_P384
TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256_P256
TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA384_P384
TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256_P256
TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA_P384
TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA_P256
TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA_P384
TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA_P256
TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA_P384
TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA_P256
TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P384
TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256
TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA_P384
TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA_P256
TLS_RSA_WITH_AES_256_CBC_SHA256
TLS_RSA_WITH_AES_256_CBC_SHA
TLS_RSA_WITH_AES_128_CBC_SHA256
TLS_RSA_WITH_AES_128_CBC_SHA
TLS_RSA_WITH_NULL_SHA256
TLS_RSA_WITH_NULL_SHA

DirectAccess and the Logjam Attack

Once complete, restart the DirectAccess server. The Qualys SSL Labs server test should no longer give a warning about the use of weak Diffie-Hellman keys. In addition, this reordering and optimization of cipher suites will also improve the protocol support and key exchange scores, as shown here.

DirectAccess and the Logjam Attack

As a reminder, and overall rating of “F” is expected when testing a dedicated DirectAccess server. By design, DirectAccess provides support for null cipher suites to improve scalability and performance for Windows 8.x and later DirectAccess clients. More details here.

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