Troubleshooting Always On VPN Error Code 809

When testing an Always On VPN connection, the administrator may encounter a scenario where the VPN client fails to connect to the VPN server. On the Windows 10 client the error message states the following.

“Can’t connect to [connection name]. The network connection between your computer and the VPN server could not be established because the remote server is not responding. This could be because one of the network devices (e.g. firewalls, NAT, routers, etc.) between your computer and the remote server is not configured to allow VPN connections. Please contact your Administrator or your service provider to determine which device may be causing the problem.”

Always On VPN and IKEv2 Fragmentation

In addition, the Application event log records an error message with Event ID 20227 from the RasClient source. The error message states the following.

“The User [username] dialed a connection named [connection name] with has failed. The error code returned on failure is 809.”

Troubleshooting Always On VPN Error Code 809

Connection Timeout

The error code 809 indicates a VPN timeout, meaning the VPN server failed to respond. Often this is related directly to network connectivity, but sometimes other factors can come in to play.

Troubleshooting VPN Error Code 809

When troubleshooting VPN error code 809 the following items should be carefully checked.

  • Name Resolution – Ensure the VPN server’s public hostname resolves to the correct IP address.
  • Firewall Configuration – Confirm the edge firewall is configured properly. Inbound TCP port 443 is required for the Secure Socket Tunneling Protocol (SSTP) and inbound UDP ports 500 and 4500 are required for the Internet Key Exchange version 2 (IKEv2) protocol. Make sure that any NAT rules are forwarding traffic to the correct server.
  • Load Balancer Configuration – If VPN servers are located behind a load balancer, make certain that virtual IP address and ports are configured correctly and that health checks are passing. For IKEv2 specifically, it is crucial that UDP ports 500 and 4500 be delivered to the same backend server. This commonly requires custom configuration. For example, on the KEMP LoadMaster the administrator will configure “port following”. On the F5 BIG-IP a  custom “persistence profile” must be configured. On the Citrix NetScaler a “persistency group” must be defined.

IKEv2 Fragmentation

VPN error code 809 can also be caused by IKE fragmentation when using the IKEv2 VPN protocol. During IKEv2 connection establishment, payload sizes may exceed the IP Maximum Transmission Unit (MTU) for the network path between the client and server. This causes the IP packets to be fragmented. However, it is not uncommon for intermediary devices (routers, NAT devices, or firewalls) to block IP fragments. When this occurs, a VPN connection cannot be established. However, looking at a network trace of the connection attempt, the administrator will see that the connection begins but subsequently fails.

Troubleshooting Always On VPN Error Code 809

Enable IKEv2 Fragmentation Support

The IKEv2 protocol includes support for fragmenting packets at the IKE layer. This eliminates the need for fragmenting packets at the IP layer. IKEv2 fragmentation must be configured on both the client and server.

Client

IKEv2 fragmentation was introduced in Windows 10 1803 and is enabled by default. No client-side configuration is required.

Server

IKEv2 is commonly supported on many firewall and VPN devices. Consult the vendor’s documentation for configuration guidance. For Windows Server Routing and Remote Access (RRAS) servers, IKEv2 fragmentation was introduced in Windows Server 1803 and is also supported in Windows Server 2019. It is enabled via a registry key. The following PowerShell command can be used to enable IKEv2 fragmentation on supported servers.

New-ItemProperty -Path “HKLM:\SYSTEM\CurrentControlSet\Services\RemoteAccess\Parameters\Ikev2\” -Name EnableServerFragmentation -PropertyType DWORD -Value 1 -Force

Validation

Once IKEv2 fragmentation is configured on the VPN server, a network capture will reveal the IKE_SA_INIT packet now includes the IKEV2_FRAGMENTATION_SUPPORTED notification message.

Always On VPN and IKEv2 Fragmentation

Additional Information

Windows 10 Always On VPN and IKEv2 Fragmentation

Windows 10 Always On VPN IKEv2 Security Configuration

Windows 10 Always On VPN Hands-On Training Classes

Always On VPN and Network Policy Server (NPS) Load Balancing

Always On VPN and Network Policy Server (NPS) Load BalancingLoad balancing Windows Server Network Policy Servers (NPS) is straightforward in most deployment scenarios. Most VPN servers, including Windows Server Routing and Remote Access Service (RRAS) servers allow the administrator to configure multiple NPS servers for redundancy and scalability. In addition, most solutions support weighted distribution, allowing administrators to distribute requests evenly between multiple NPS servers (round robin load balancing) or to distribute them in order of priority (active/passive failover).

The Case for NPS Load Balancing

Placing NPS servers behind a dedicated network load balancing appliance is not typically required. However, there are some deployment scenarios where doing so can provide important advantages.

Deployment Flexibility

Having NPS servers fronted by a network load balancer allows the administrator to configure a single, virtual IP address and hostname for the NPS service. This provides deployment flexibility by allowing administrators to add or remove NPS servers without having to reconfigure VPN servers, network firewalls, or VPN clients. This can be beneficial when deploying Windows updates, migrating NPS servers to different subnets, adding more NPS servers to increase capacity, or performing rolling upgrades of NPS servers.

Traffic Shaping

Dedicated network load balancers allow for more granular control and of NPS traffic. For example, NPS routing decisions can be based on real server availability, ensuring that authentication requests are never sent to an NPS server that is offline or unavailable for any reason. In addition, NPS traffic can be distributed based on server load, ensuring the most efficient use of NPS resources. Finally, most load balancers also support fixed or weighted distribution, enabling active/passive failover scenarios if required.

Traffic Visibility

Using a network load balancer for NPS also provides better visibility for NPS authentication traffic. Most load balancers feature robust graphical displays of network utilization for the virtual server/service as well as backend servers. This information can be used to ensure enough capacity is provided and to monitor and plan for additional resources when network traffic increases.

Configuration

Before placing NPS servers behind a network load balancer, the NPS server certificate must be specially prepared to support this unique deployment scenario. Specifically, the NPS server certificate must be configured with the Subject name of the cluster, and the Subject Alternative Name field must include both the cluster name and the individual server’s hostname.

Always On VPN and Network Policy Server (NPS) Load Balancing

Always On VPN and Network Policy Server (NPS) Load Balancing

Create Certificate Template

Perform the following steps to create a certificate template in AD CS to support NPS load balancing.

  1. Open the Certificate Templates management console (certtmpl.msc) on the certification authority (CA) server or a management workstation with remote administration tool installed.
  2. Right-click the RAS and IAS Servers default certificate template and choose Duplicate.
  3. Select the Compatibility tab.
    1. Select Windows Server 2008 or a later version from the Certification Authority drop-down list.
    2. Select Windows Vista/Server 2008 or a later version from the Certificate recipient drop-down list.
  4. Select the General tab.
    1. Enter a descriptive name in the Template display name field.
    2. Choose an appropriate Validity period and Renewal period.
    3. Do NOT select the option to Publish certificate in Active Directory.
  5. Select the Cryptography tab.
    1. Chose Key Storage Provider from the Provider Category drop-down list.
    2. Enter 2048 in the Minimum key size field.
    3. Select SHA256 from the Request hash drop-down list.
  6. Select the Subject Name tab.
    1. Select the option to Supply in the request.
  7. Select the Security tab.
    1. Highlight RAS and IAS Servers and click Remove.
    2. Click Add.
    3. Enter the security group name containing all NPS servers.
    4. Check the Read and Enroll boxes in the Allow column in the Permissions for [group name] field.
  8. Click Ok.

Perform the steps below to publish the new certificate template in AD CS.

  1. Open the Certification Authority management console (certsrv.msc) on the certification authority (CA) server or a management workstation with remote administration tool installed.
  2. Expand Certification Authority (hostname).
  3. Right-click Certificate Templates and choose New and Certificate Template to Issue.
  4. Select the certificate template created previously.
  5. Click Ok.

Request Certificate on NPS Server

Perform the following steps to request a certificate for the NPS server.

  1. Open the Certificates management console (certlm.msc) on the NPS server.
  2. Expand the Personal folder.
  3. Right-click Certificates and choose All Tasks and Request New Certificate.
  4. Click Next.
  5. Click Next.
  6. Select the NPS server certificate template and click More information is required to enroll for this certificate link.
  7. Select the Subject tab.
    1.  Select Common name from the Type drop-down list in the Subject name section.
    2. Enter the cluster fully-qualified hostname (FQDN) in the Value field.
    3. Click Add.
    4. Select DNS from the Type drop-down list in the Alternative name section.
    5. Enter the cluster FQDN in the Value field.
    6. Click Add.
    7. Enter the NPS server’s FQDN in the Value field.
    8. Click Add.
      Always On VPN and Network Policy Server (NPS) Load Balancing
  8. Select the General tab.
    1. Enter a descriptive name in the Friendly name field.
  9. Click Ok.
  10. Click Enroll.

Load Balancer Configuration

Configure the load balancer to load balance UDP ports 1812 (authentication) and 1813 (accounting). Optionally, to ensure that authentication and accounting requests go to the same NPS server, enable source IP persistence according to the vendor’s guidance. For the KEMP LoadMaster load balancer, the feature is called “port following”. On the F5 BIG-IP it is called a “persistence profile”, and on the Citrix NetScaler it is called a “persistency group”.

Additional Information

Always On VPN IKEv2 Load Balancing with KEMP LoadMaster

Always On VPN Hands-On Training Classes in U.S. and Europe

Always On VPN and Windows Server 2019 NPS Bug

When deploying a Windows Server 2019 Network Policy Server (NPS) to support a Windows 10 Always On VPN implementation, administrators may encounter the following error when attempting to establish a VPN connection on a remote Windows 10 client.

Can’t connect to [connection name].

The connection was prevented because of a policy configured on your RAS/VPN server. Specifically, the authentication method used by the server to verify your username and password may not match the authentication method configured in your connection profile. Please contact the Administrator of the RAS server and notify them of this error.

Always On VPN and Windows Server 2019 Network Policy Server Bug
In addition, an event ID 20227 from the RasClient will be recorded in the application event log with the following error message.

The user [username] dialed a connection named [connection name] which has failed. The error code returned on failure is 812.

Always On VPN and Windows Server 2019 Network Policy Server Bug

Common Causes

Always On VPN error code 812 indicates an authentication policy mismatch between the client and the server. This often occurs when, for example, the server is configured to use Protected Extensible Authentication Protocol (PEAP), but the client is configured to use Microsoft CHAP Version 2 (MS-CHAP v2).

Troubleshooting

Carefully review the authentication policy on both the client and server to ensure they match. Next, enable firewall logging on the NPS server to log both allowed and dropped packets. Attempt another VPN connection and observe the firewall logs. In this example the firewall is dropping packets inbound on UDP port 1812.

Always On VPN and Windows Server 2019 Network Policy Server Bug

Interestingly, the default Windows firewall rule allowing inbound UDP port 1812 is enabled and set to allow for all profiles.

Always On VPN and Windows Server 2019 Network Policy Server Bug

Windows Server 2019 Bug

It appears that Microsoft’s recently released Windows Server 2019 has a bug that prevents NPS from working correctly out of the box. Specifically, it appears the default Windows firewall rules to allow inbound UDP port 1812 (RADIUS authentication) and inbound UDP port 1813 (RADIUS accounting) do not work. As a workaround the administrator can create new firewall rules to allow inbound UDP port 1812 and 1813 and restore NPS operation using the following PowerShell commands.

New-NetFirewallRule -Name “NPS-UDP-1812-In” -DisplayName “Network Policy Server (RADIUS Authentication – UDP-in)” -Description “Inbound rule to allow Network Policy Server to receive RADIUS authentication requests on UDP port 1812” -Group “Network Policy Server” -Protocol UDP -LocalPort 1812 -Direction Inbound -Profile Any -Action Allow -Enabled True

New-NetFirewallRule -Name “NPS-UDP-1813-In” -DisplayName “Network Policy Server (RADIUS Accounting – UDP-in)” -Description “Inbound rule to allow Network Policy Server to receive RADIUS accounting requests on UDP port 1813” -Group “Network Policy Server” -Protocol UDP -LocalPort 1813 -Direction Inbound -Profile Any -Action Allow -Enabled True

DirectAccess IP-HTTPS Performance Issues

DirectAccess IP-HTTPS Performance IssuesPerformance issues with DirectAccess are not uncommon. In fact, there are numerous threads on Microsoft and third-party forums where administrators frequently complain about slow download speeds, especially when using the IP-HTTPS IPv6 transition technology. Based on my experience the problem does not appear to be widespread but occurs with enough regularity that it is worthy of further investigation.

DirectAccess Design

The inherent design of DirectAccess is a major limiting factor for performance. DirectAccess uses a complex and heavy communication channel, with multiple layers of encapsulation, encryption, and translation. Fundamentally it is IPsec encrypted IPv6 traffic, encapsulated in HTTP, and then encrypted with Transport Layer Security (TLS) and routed over IPv4. It is then decrypted, decapsulated, decrypted again, then converted back to IPv4. The high protocol overhead incurred with multiple layers of encapsulation, encryption, and translation result in increased packet fragmentation, which further reduces performance.

DirectAccess Performance

Even under the best circumstances, DirectAccess performance is limited by many other factors, most notably the quality of the network connection between the client and the server. DirectAccess performs reasonably well over high bandwidth, low latency connections. However, network performance drops precipitously as latency increases and packet loss is encountered. This is to be expected given the design of the solution.

Intermediary Devices

It is not uncommon to find intermediary devices like firewalls, intrusion detection systems, malware scanners, and other security inspection devices limit the performance of DirectAccess clients. In addition, many security appliances have bandwidth caps enforced in software for licensing restrictions. Further, incorrect configuration of inline edge devices can contribute to increased fragmentation, which leads to poor performance as well.

Slow Downloads over IP-HTTPS

Many people report that download speeds seem to be artificially capped at 355Kbps. While this seems to be a display bug in the UI, there is plenty of evidence to indicate that, in some scenarios, DirectAccess is incapable of high throughput even over high-quality connections. Some who have deployed DirectAccess and VPN on the same server have reported that download speeds are only limited when using DirectAccess over IP-HTTPS and not with VPN using Secure Socket Tunneling Protocol (SSTP), which also uses TLS. This has led many to speculate that the issue is either a bug or a design flaw in the IP-HTTPS tunnel interface itself.

TCP Window Scaling Issues

In some of the network traces I’ve analyzed I’ve seen evidence that seems to support this theory. For example, a network trace taken when downloading a file over DirectAccess with IP-HTTPS showed the TCP window never scaled beyond 64K, which would seriously impede performance. Interestingly this doesn’t seem to happy when the client uploads files over IP-HTTPS. Clearly something unusual is happening.

Microsoft KB Article

Microsoft recently released a vaguely-worded KB article that appears to lend credence to some of these findings. The article seems to acknowledge the fact there are known issues with DirectAccess performance, but it lacks any specific details as to what the root cause is. Instead, it simply advises migrating to Windows 10 Always On VPN.

Summary

DirectAccess IP-HTTPS performance issues don’t appear to affect everyone, and the problem only seems to apply to file downloads and not to other types of traffic. However, there is mounting evidence of a systemic issue with DirectAccess performance especially over IP-HTTPS. Customers are advised to closely evaluate their uses cases for DirectAccess and if remote clients are frequently required to download large files over a DirectAccess connection, an alternative method of file transfer might be required. Optionally customers can consider evaluating alternative remote access solutions that offer better performance such as Windows 10 Always On VPN or third-party solutions such as NetMotion Mobility.

Additional Resources

Always On VPN and the Future of DirectAccess

What’s the Difference Between DirectAccess and Always On VPN?

NetMotion Mobility as an Alternative to Microsoft DirectAccess

DirectAccess Manage Out with ISATAP and NLB Clustering

DirectAccess Manage Out with ISATAP and NLB ClusteringDirectAccess connections are bidirectional, allowing administrators to remotely connect to clients and manage them when they are out of the office. DirectAccess clients use IPv6 exclusively, so any communication initiated from the internal network to remote DirectAccess clients must also use IPv6. If IPv6 is not deployed natively on the internal network, the Intrasite Automatic Tunnel Addressing Protocol (ISATAP) IPv6 transition technology can be used to enable manage out.

ISATAP Supportability

According to Microsoft’s support guidelines for DirectAccess, using ISATAP for manage out is only supported for single server deployments. ISATAP is not supported when deployed in a multisite or load-balanced environment.

Not supported” is not the same as “doesn’t work” though. For example, ISATAP can easily be deployed in single site DirectAccess deployments where load balancing is provided using Network Load Balancing (NLB).

ISATAP Configuration

To do this, you must first create DNS A resource records for the internal IPv4 address for each DirectAccess server as well as the internal virtual IP address (VIP) assigned to the cluster.

DirectAccess Manage Out with ISATAP and NLB Clustering

Note: Do NOT use the name ISATAP. This name is included in the DNS query block list on most DNS servers and will not resolve unless it is removed. Removing it is not recommended either, as it will result in ALL IPv6-enabled hosts on the network configuring an ISATAP tunnel adapter.

Once the DNS records have been added, you can configure a single computer for manage out by opening an elevated PowerShell command window and running the following command:

Set-NetIsatapConfiguration -State Enabled -Router [ISATAP FQDN] -PassThru

DirectAccess Manage Out with ISATAP and NLB Clustering

Once complete, an ISATAP tunnel adapter network interface with a unicast IPv6 address will appear in the output of ipconfig.exe, as shown here.

DirectAccess Manage Out with ISATAP and NLB Clustering

Running the Get-NetRoute -AddressFamily IPv6 PowerShell command will show routes to the client IPv6 prefixes assigned to each DirectAccess server.

DirectAccess Manage Out with ISATAP and NLB Clustering

Finally, verify network connectivity from the manage out host to the remote DirectAccess client.

Note: There is a known issue with some versions of Windows 10 and Windows Server 2016 that may prevent manage out using ISATAP from working correctly. There’s a simple workaround, however. More details can be found here.

Group Policy Deployment

If you have more than a few systems on which to enable ISATAP manage out, using Active Directory Group Policy Objects (GPOs) to distribute these settings is a much better idea. You can find guidance for creating GPOs for ISATAP manage out here.

DirectAccess Client Firewall Configuration

Simply enabling ISATAP on a server or workstation isn’t all that’s required to perform remote management on DirectAccess clients. The Windows firewall running on the DirectAccess client computer must also be configured to securely allow remote administration traffic from the internal network. Guidance for configuring the Windows firewall on DirectAccess clients for ISATAP manage out can be found here.

ISATAP Manage Out for Multisite and ELB

The configuration guidance in this post will not work if DirectAccess multisite is enabled or external load balancers (ELB) are used. However, ISATAP can still be used. For more information about enabling ISATAP manage out with external load balancers and/or multisite deployments, fill out the form below and I’ll provide you with more details.

Summary

Once ISATAP is enabled for manage out, administrators on the internal network can remotely manage DirectAccess clients wherever they happen to be. Native Windows remote administration tools such as Remote Desktop, Windows Remote Assistance, and the Computer Management MMC can be used to manage remote DirectAccess clients. In addition, enterprise administration tools such as PowerShell remoting and System Center Configuration Manger (SCCM) Remote Control can also be used. Further, third-party remote administration tools such as VNC, TeamViewer, LogMeIn, GoToMyPC, Bomgar, and many others will also work with DirectAccess ISATAP manage out.

Additional Information

ISATAP Recommendations for DirectAccess Deployments

DirectAccess Manage Out with ISATAP Fails on Windows 10 and Windows Server 2016 

DirectAccess Client Firewall Rule Configuration for ISATAP Manage Out

DirectAccess Manage Out and System Center Configuration Manager (SCCM)

Contact Me

Interested in learning more about ISATAP manage out for multisite and external load balancer deployments? Fill out the form below and I’ll get in touch with you.

DirectAccess Force Tunneling and Proxy Server Configuration

By default, DirectAccess is configured to use split tunneling. In this scenario, a remote DirectAccess client is connected to the internal corporate network and the public Internet at the same time. Some security administrators perceive split tunneling as a security risk, and the use of split tunneling may be prohibited by corporate security policy. In addition, enforcing web browsing policies on remote DirectAccess clients might be desired to reduce the risk of exposure from browsing unapproved web sites. In either case, force tunneling can be configured to meet these requirements.

When force tunneling is enabled, DirectAccess administrators can also define an on-premises proxy server for DirectAccess clients to use. The following is guidance for enabling force tunneling and configuring DirectAccess clients to use a proxy server to access the Internet.

Enabling Force Tunneling

To enable force tunneling, open the Remote Access Management console and perform the following steps.

  1. Expand Configuration and select DirectAccess and VPN.
  2. Click Edit on Step 1 Remote Clients.
  3. Click Select Groups in the navigation tree.
  4. Select the option to Use force tunneling.

DirectAccess Force Tunneling and Proxy Server ConfigurationFigure 1. Enable DirectAccess force tunneling in the Remote Access Management console.

Alternatively, force tunneling can quickly be enabled by opening an elevated PowerShell command window and running the following command.

Set-DAClient -ForceTunnel Enabled -PassThru

DirectAccess Force Tunneling and Proxy Server ConfigurationFigure 2. Enable DirectAccess force tunneling using PowerShell.

Configure a Proxy Server

Once force tunneling has been enabled, run the following PowerShell script to configure an on-premises proxy server for DirectAccess clients to use. Be sure to substitute the fully-qualified domain name (FQDN) and port for your proxy server in the $proxy variable below.

$gpo = (Get-RemoteAccess).ClientGpoName
$gpo = $gpo.Split(‘\’)[1]

$proxy = “proxy.corp.example.net:8080”

$rule = (Get-DnsClientNrptRule -GpoName $gpo | Where-Object Namespace -eq “.” | Select-Object -ExpandProperty “Name”)

Set-DnsClientNrptRule -DAEnable $true -DAProxyServerName $proxy -DAProxyType “UseProxyName” -Name $rule -GpoName $gpo

If multisite is enabled and Windows 7 clients are supported, run the following PowerShell script on one DirectAccess server in each entry point.

$downlevelgpo = (Get-RemoteAccess).DownlevelGpoName
$downlevelgpo = $downlevelgpo.Split(‘\’)[1]

$proxy = “proxy.corp.example.net:8080”

$downlevelrule = (Get-DnsClientNrptRule -GpoName $downlevelgpo | Where-Object Namespace -eq “.” | Select-Object -ExpandProperty “Name”)

Set-DnsClientNrptRule -DAEnable $true -DAProxyServerName $proxy -DAProxyType “UseProxyName” -Name $downlevelrule -GpoName $downlevelgpo

Remove Proxy Server

Run the following PowerShell script to remove the proxy server, if necessary.

$gpo = (Get-RemoteAccess).ClientGpoName
$gpo = $gpo.Split(‘\’)[1]

Set-DnsClientNrptRule -DAEnable $true -DAProxyType “UseDefault” -Name $rule -GpoName $gpo

$downlevelgpo = (Get-RemoteAccess).DownlevelGpoName
$downlevelgpo = $downlevelgpo.Split(‘\’)[1]

Set-DnsClientNrptRule -DAEnable $true -DAProxyType “UseDefault” -Name $downlevelrule -GpoName $downlevelgpo

Disable Force Tunneling

To disable force tunneling completely, run the following PowerShell command.

Set-DAClient -ForceTunnel Disabled -PassThru

Force Tunneling Caveats

When force tunneling is enabled, the user experience is typically poor when accessing the Internet. Web browsing performance is significantly reduced because of the added protocol overhead imposed by DirectAccess IPv6 transition technologies and IPsec encryption. This problem is further compounded when users access resources that are already encrypted, such as secure web sites. Increased packet fragmentation, along with the additional network latency caused by suboptimal network paths and increased network load on the server and Internet connection all contribute to degraded network performance for DirectAccess clients.

Force Tunneling Alternatives

Instead of enabling force tunneling, consider alternative solutions to address the security concerns associated with split tunneling. For example, implement technologies that enforce web browsing policies on the client. Many secure web gateways and next-generation firewalls (NGFW) have remote filtering capabilities that allow administrators to enforce web browsing policies on remote client machines. In addition, there are some excellent cloud-based solutions such as Zscaler and OpenDNS that can protect DirectAccess clients without the drawbacks associated with force tunneling.

Additional Information

Planning and Implementing DirectAccess with Windows Server 2016 video training course on Pluralsight
Managing and Supporting DirectAccess with Windows Server 2016 video training course 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

DirectAccess Troubleshooting with Nmap

DirectAccess IP-HTTPS Discovery Script for NmapDirectAccess troubleshooting can be made much easier using open source tools such as Nmap. Nmap can be used to perform many essential network connectivity and configuration checks, including validating network paths, confirming DirectAccess server response, and viewing SSL configuration. Nmap can also be used to ensure that the attack surface of the DirectAccess server is properly minimized. Some tests can be performed using only native Nmap functionality, while others require the use of specialized Nmap scripts that are included with the tool.

Installation

Nmap can be installed on a wide variety of operating systems, including Windows. If you plan to install Nmap on Windows, be sure to also install WinPcap and the Microsoft Visual C++ 2013 Redistributable. The Visual C++ component is included with the Nmap download. WinPcap must be downloaded separately here.

Testing External Connectivity

Validating external connectivity is often one of the first DirectAccess troubleshooting steps I take. Confirm that the DirectAccess public hostname resolves to the correct IP address, then run the following Nmap command to validate network connectivity from the Internet to the DirectAccess server.

nmap -n -Pn -p443 <da_public_hostname>

DirectAccess Troubleshooting with Nmap

If the hostname resolves correctly and the network path is complete, the server should respond and Nmap will show the port as open. However, this doesn’t necessarily mean that the DirectAccess server is the device that replied! Due to misconfiguration, it is possible that another server or network device listening on TCP port 443 responded, so this is not a conclusive test.

DirectAccess Server Response

To confirm the DirectAccess server is responding to HTTPS requests and not some other server or device, run the following Nmap command with the ip-https-discover script.

nmap -n -Pn -p443 <da_public_hostname> –script ip-https-discover

If the DirectAccess server responds to the request, Nmap will return the following message:

IP-HTTPS is supported. This indicates that this host supports Microsoft DirectAccess.

DirectAccess Troubleshooting with Nmap

If the port is open but the script does not return this message, it is likely that another server or device is responding on TCP port 443, not the DirectAccess server.

Note: If an Application Delivery Controller (ADC) is configured to perform IP-HTTPS preauthentication, the Nmap IP-HTTPS discovery script will not return this result. This is expected and by design.

SSL Certificate Validation

It is not uncommon for DirectAccess clients to fail to connect via IP-HTTPS because of SSL certificate issues. Specifically, an SSL certificate that is not trusted, is expired, or its subject field does not match the public hostname will prevent DirectAccess clients from connecting. To view the SSL certificate configuration of a DirectAccess server, run the following Nmap command with the ssl-cert script.

nmap -n -Pn -p443 <da_public_hostname> –script ssl-cert

DirectAccess Troubleshooting with Nmap

SSL Cipher Suite Configuration

Occasionally there can be issues with the SSL configuration on the DirectAccess server that prevent some clients from connecting, or result in poor performance. This commonly occurs when administrators perform SSL hardening on the DirectAccess server and remove support for null cipher suites. Null cipher suites should never be disabled on the DirectAccess server. They are important to ensure the highest levels of performance for Windows 8.x and Windows 10 clients. Also, if an Application Delivery Controller (ADC) or load balancer is performing SSL offload, lack of support for null cipher suites will prevent Windows 8.x and Windows 10 clients from connecting. To determine if the DirectAccess server supports null cipher suites, run the following Nmap command with the ssl-enum-ciphers script.

nmap -n -Pn -p443 <da_public_hostname> –script ssl-enum-ciphers

DirectAccess Troubleshooting with Nmap

Attack Surface Audit

If DirectAccess implementation and security best practices are followed, the DirectAccess server will be behind an edge firewall. The only port required to be allowed inbound for DirectAccess is TCP port 443. It is recommended that a full port scan be performed against the DirectAccess server’s public IPv4 address to identify any unnecessary ports that may be open externally. To perform a full port scan, run the following Nmap command.

nmap -n -Pn -p- <da_public_hostname>

Ideally it should look like this.

DirectAccess Troubleshooting with Nmap

If it looks something like this, you’re in serious trouble!

DirectAccess Troubleshooting with Nmap

The DirectAccess server should never be listening for requests other that HTTPS on the public Internet. Exposing services such as SMB (TCP port 445), RDP (TCP port 3389), and others presents a significant security risk. It is recommended that edge firewalls be configured to allow inbound TCP port 443 only. If the DirectAccess server is connected directly to the public Internet (not recommended!) then the Windows Firewall should be configured to restrict access to inbound TCP port 443 only.

Additional Resources

DirectAccess IP-HTTPS Discovery Script for Nmap
Planning and Implementing DirectAccess with Windows Server 2016 on Pluralsight
Implementing DirectAccess with Windows Server 2016 Book
DirectAccess Troubleshooting and Consulting Services

3 Important Things You Need to Know about Windows 10 and DirectAccess

DirectAccess and Windows 10 - Better TogetherDirectAccess has been with us for quite some time know, having been originally introduced with Windows Server 2008 R2, later enhanced with Forefront Unified Access Gateway (UAG) 2010, and finally integrated in to the base operating system in Windows Server 2012 R2. Client support for DirectAccess begins with Windows 7 (Enterprise or Ultimate), and also includes Windows 8.x (Enterprise) and Windows 10 (Enterprise or Education).

Although Windows 7 clients are supported for DirectAccess, Windows 10 is highly preferred. Here are three important things you need to know about using Windows 10 with DirectAccess.

  1. Windows 10 Provides Improved Performance and Scalability – Windows 10 includes support for null encryption when using the IP-HTTPS IPv6 transition protocol. This eliminates the needless double-encryption performed by Windows 7 clients, and dramatically reduces the protocol overhead for clients connecting behind port-restricted firewalls. DirectAccess servers can support many more concurrent IP-HTTPS sessions with Windows 10, and it has the added benefit of making the more secure perimeter/DMZ deployment behind an edge security device performing NAT much more attractive.
  2. Windows 10 Supports Geographic Redundancy – Windows 10 includes full support for DirectAccess multisite deployments. Where Windows 7 clients had to be assigned to a single entry point, Windows 10 clients are aware of all entry points in the organization. They are able to automatically select the nearest entry point on startup, and transparently failover to another site if the current site becomes unavailable.
  3. Windows 10 Features an Enhanced Management Experience – From a troubleshooting and support perspective, Windows 10 makes things much easier. The DirectAccess connectivity assistant, an optional component for Windows 7, is now fully integrated with the Windows 10 UI. PowerShell is greatly improved and now includes many native DirectAccess configuration and troubleshooting commands.

As you can see, there are a number of significant advantages for using Windows 10 with DirectAccess. Windows 10 now supports all of the enterprise features of DirectAccess, including geographic redundancy and performance and scalability improvements. Windows 10 is also easier to troubleshoot and manage. If you’re still supporting Windows 7, DirectAccess in Windows Server 2012 R2 can certainly support them. However, without a doubt the best experience, both from an administrator’s and the end user’s perspective, is with Windows 10. Just one more reason to begin planning your migration to Windows 10 with DirectAccess today!

Need assistance with implementing  DirectAccess with Windows 10? I can help! More details here.

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