Always On VPN IKEv2 Load Balancing Issue with Kemp LoadMaster

Always On VPN IKEv2 Load Balancing Issue with Kemp LoadMasterA recent update to the Kemp LoadMaster load balancer may cause failed connections for Always On VPN connections using IKEv2. SSTP VPN connections are unaffected.

Load Balancing IKEv2

When using the Kemp LoadMaster load balancer to load balance IKEv2, custom configuration is required to ensure proper operation. Specifically, the virtual service must be configured to use “port following” to ensure both the initial request on UDP port 500 and the subsequent request on UDP port 4500 are sent to the same real server. This requires the virtual service to be configured to operate at layer 7. Detailed configuration guidance for load balancing IKEv2 on the Kemp LoadMaster load balancer can be found here.

Always On VPN IKEv2 Load Balancing Issue with Kemp LoadMaster

Issues with LMOS 7.2.48.0

A recent release of the Load Master Operating System (LMOS) v7.2.48.0 introduced a bug that affects UDP services configured to operate at layer 7, which includes IKEv2. This bug breaks Always On VPN connections using IKEv2, resulting in failed connections. When this occurs, the administrator may encounter an error 809 message for device tunnel or user tunnel.

Always On VPN IKEv2 Load Balancing Issue with Kemp LoadMaster

Update Available

Administrators who use the Kemp LoadMaster load balancer to load balance Always On VPN IKEv2 connections and have updated to LMOS 7.2.48.0 are encouraged to update to LMOS 7.2.48.1 immediately. This latest update includes a fix that resolves broken IKEv2 load balancing for Always On VPN. Once the LoadMaster has been updated to 7.2.48.1, Always On VPN connections using IKEv2 should complete successfully.

Additional Information

Windows 10 Always On VPN IKEv2 Load Balancing with Kemp LoadMaster Load Balancer

Windows 10 Always On VPN SSTP Load Balancing with Kemp LoadMaster Load Balancer

Windows 10 Always On VPN Load Balancing with Kemp LoadMaster in Azure

Windows 10 Always On VPN Load Balancing Deployment Guide for Kemp Load Balancers

Always On VPN Load Balancing with Kemp in Azure

Always On VPN Load Balancing with Kemp in AzureIn a recent post I discussed options for load balancing Windows Server Routing and Remote Access Service (RRAS) in Microsoft Azure for Always On VPN. There are many choices available to the administrator, however the best alternative is to use a dedicated Application Delivery Controller (ADC), or load balancer. The Kemp LoadMaster load balancer is an excellent choice here, as it is easy to configure and deploy. It is also very cost effective and offers flexible licensing plans, including a metered licensing option.

Deploy LoadMaster in Azure

To provision a Kemp LoadMaster load balancer in Microsoft Azure, open the Azure management console and perform the following steps.

1. Click Create Resource.
2. Enter LoadMaster in the search field.
3. Click on LoadMaster Load Balancer ADC Content Switch.

Always On VPN Load Balancing with Kemp in Azure

4. Choose an appropriate license model from the Select a software plan drop-down list.
5. Click Create.

Prepare Azure Instance

Follow the steps below to provision the Azure VM hosting the Kemp LoadMaster load balancer.

1. Choose an Azure subscription to and resource group to deploy the resources to.
2. Provide instance details such as virtual machine name, region, availability options, and image size.
3. Select an authentication type and upload the SSH private key or provide a username and password.
4. Click Next:Disks >.

Always On VPN Load Balancing with Kemp in Azure

5. Select an OS disk type.
6. Click Next: Networking >.

Always On VPN Load Balancing with Kemp in Azure

7. Select a virtual network and subnet for the load balancer.
8. Create or assign a public IP address.
9. Click Review + create.

Always On VPN Load Balancing with Kemp in Azure

LoadMaster Configuration

Once the virtual machine has been provisioned, open a web browser and navigate to the VM’s internal IP address on port 8443 to accept the licensing terms.

Always On VPN Load Balancing with Kemp in Azure

Next, log in with your Kemp ID and password to finish licensing the appliance.

Always On VPN Load Balancing with Kemp in Azure

Finally, log in to the appliance using the username ‘bal’ and the password provided when the virtual machine was configured.

Always On VPN Load Balancing with Kemp in Azure

Azure Network Security Group

A Network Security Group (NSG) is automatically configured and associated with the LoadMaster’s network interface when the appliance is created. Additional inbound security rules must be added to allow VPN client connectivity.

In the Azure management console open the properties for the LoadMaster NSG and follow the steps below to configure security rules to allow inbound VPN protocols.

SSTP

1. Click Inbound security rules.
2. Click Add.
3. Choose Any from the Source drop-down list.
4. Enter * in the Source port ranges field.
5. Select Any from the Destination drop-down list.
6. Enter 443 in the Destination port ranges field.
7. Select the TCP protocol.
8. Select the Allow action.
9. Enter a value in the Priority field.
10. Enter a name for the service in the Name field.
11. Click Add.

Always On VPN Load Balancing with Kemp in Azure

IKEv2

1. Click Inbound security rules.
2. Click Add.
3. Choose Any from the Source drop-down list.
4. Enter * in the Source port ranges field.
5. Select Any from the Destination drop-down list.
6. Enter 500 in the Destination port ranges field.
7. Select the UDP protocol.
8. Select the Allow action.
9. Enter a value in the Priority field.
10. Enter a name for the service in the Name field.
11. Click Add.
12. Repeat the steps below for UDP port 4500.

Always On VPN Load Balancing with Kemp in Azure

Load Balancing SSTP and IKEv2

Refer to the following posts for detailed, prescriptive guidance for configuring the Kemp LoadMaster load balancer for Always On VPN load balancing.

Always On VPN SSTP Load Balancing with Kemp LoadMaster

Always On VPN IKEv2 Load Balancing with the Kemp LoadMaster

Always On VPN Load Balancing Deployment Guide for the Kemp LoadMaster

Summary

Although Windows Server RRAS is not a formally supported workload in Azure, it is still a popular and effective solution for Always On VPN deployments. The Kemp LoadMaster load balancer can be deployed quickly and easily to provide redundancy and increase scalability for larger deployments.

Additional Information

Windows 10 Always On VPN SSTP Load Balancing with Kemp LoadMaster Load Balancers

Windows 10 Always On VPN IKEv2 Load Balancing with Kemp LoadMaster Load Balancers

Windows 10 Always On VPN Load Balancing Deployment Guide for Kemp LoadMaster Load Balancers

Deploying the Kemp LoadMaster Load Balancer in Microsoft Azure

Always On VPN SSTP Load Balancing with Kemp LoadMaster

Always On VPN SSTP Load Balancing with Kemp LoadMaster The Windows Server Routing and Remote Access Service (RRAS) includes support for the Secure Socket Tunneling Protocol (SSTP), which is a Microsoft proprietary VPN protocol that uses SSL/TLS for security and privacy of VPN connections. The advantages of using SSTP for Always On VPN is that it is firewall friendly and ensures consistent remove connectivity even behind highly restrictive firewalls.

Load Balancing SSTP

In a recent post, I described some of the use cases and benefits of SSTP load balancing as well as the offloading of TLS for SSTP VPN connections. Using a load balancer for SSTP VPN connections increases scalability, and offloading TLS for SSTP reduces resource utilization and improves performance for VPN connections. There are positive security benefits too.

Note: A comprehensive reference with detailed, prescriptive guidance for configuring the Kemp LoadMaster for Always On VPN can be found in the Always On VPN Load Balancing Deployment Guide for Kemp Load Balancers. Download this free guide now!

Configuration

Enabling load balancing on the Kemp LoadMaster platform is fundamentally similar to load balancing HTTPS web servers. However, there are a few subtle but important differences.

Health Check

Using a standard TCP port check on the LoadMaster will not accurately reflect the health of the SSTP service running on the RRAS server. In addition, using a simple TCP port check could yield unexpected results. To ensure accurate service status monitoring, it is recommended that HTTP or HTTPS health checks be configured instead.

Real Server Check Method

Open the Kemp LoadMaster management console and follow the steps below to enable HTTP/HTTPS health checks for SSTP.

1. Expand Virtual Services in the navigation pane.
2. Click View/Modify Services.
3. Click Modify on the SSTP VPN virtual service.
4. Expand Real Servers.
5. Select HTTPS Protocol from the Real Server Check Method drop-down list. Alternatively, if TLS offload is enabled select HTTP Protocol.
6. In the URL field enter /sra_{BA195980-CD49-458b-9E23-C84EE0ADCD75}/ and click Set URL.
7. In the Status Codes field enter 401 and click Set Status Codes.
8. Check the box next to Use HTTP/1.1.
9. Select Head from the HTTP Method drop-down list.

Always On VPN SSTP Load Balancing with Kemp LoadMaster

TLS Offload

It is generally recommended that TLS offload not be enabled for SSTP VPN. However, if TLS offload is desired, it is configured in much the same way as a common HTTPS web server. Specific guidance for enabling TLS offload on the Kemp LoadMaster load balancer can be found in the Always On VPN Load Balancing Deployment Guide for Kemp Load Balancers. Details for configuring RRAS and SSTP to support TLS offload can be found here.

Certificates

When enabling TLS offload for SSTP VPN connections it is recommended that the public SSL certificate be installed on the RRAS server, even though TLS processing will be handled on the LoadMaster and HTTP will be used between the LoadMaster and the RRAS server. If installing the public SSL certificate on the RRAS server is not an option, additional configuration will be required. Specifically, TLS offload for SSTP must be configured using the Enable-SSTPOffload PowerShell script, which can be found here.

Once the script has been downloaded, open an elevated PowerShell command window and enter the following command.

Enable-SSTPOffload -CertificateHash [SHA256 Certificate Hash of Public SSL Certificate] -Restart

Example:

Enable-SSTPOffload -CertificateHash “C3AB8FF13720E8AD9047DD39466B3C8974E592C2FA383D4A3960714CAEF0C4F2” -Restart

Re-Encryption

When offloading TLS for SSTP VPN connections, all traffic between the LoadMaster and the RRAS server will be sent in the clear using HTTP. In some instances, TLS offload is required only for traffic inspection, not performance gain. In this scenario the LoadMaster will be configured to terminate and then re-encrypt connections to the RRAS server. When terminating TLS on the LoadMaster and re-encrypting connections to the RRAS server is required, the same certificate must be used on both the LoadMaster and the RRAS server. Using different certificates on the RRAS server and the load balancer is not supported.

Additional Information

Windows 10 Always On VPN Load Balancing Deployment Guide for Kemp Load Balancers

Windows 10 Always On VPN SSTP Load Balancing and SSL Offload

Windows 10 Always On VPN SSL Certificate Requirements for SSTP

Windows 10 Always On VPN ECDSA SSL Certificate Request for SSTP

Windows 10 Always On VPN SSTP Connects then Disconnects

Windows 10 Always On VPN SSTP Load Balancing with F5 BIG-IP

Always On VPN Load Balancing Deployment Guide for Kemp Load Balancers

Always On VPN Load Balancing Deployment Guide for Kemp Load BalancersI’m pleased announce that Kemp has released their Load Balancing Deployment Guide for Windows 10 Always On VPN. Authored by yours truly, this guide provides detailed, prescriptive guidance for configuring the Kemp LoadMaster load balancer to provide important scalability and eliminate critical points of failure in Always On VPN deployments.

Configuration Guidance

Included in the guide are configuration steps for load balancing VPN servers using IKEv2 and SSTP using Kemp LoadMaster. Crucial details for IKEv2 load balancing as well as SSL offload for SSTP are covered in detail. In addition, the guide includes information about load balancing important supporting infrastructure services such as the Network Policy Server (NPS). Finally, guidance is included for enabling active/passive or active/active load balancing as well as geographic load balancing for multisite Always On VPN deployments.

Always On VPN Load Balancing Deployment Guide for Kemp Load Balancers

Download

You can download the Windows 10 Always On VPN load balancing deployment guide for Kemp LoadMaster load balancers here.

Additional Information

Windows 10 Always On VPN Load Balancing Deployment Guide for Kemp LoadMaster Load Balancers

Windows 10 Always On VPN IKEv2 Load Balancing with the Kemp LoadMaster Load Balancer

 

 

Always On VPN IKEv2 Features and Limitations

Always On VPN IKEv2 Features and LimitationsThe Internet Key Exchange version 2 (IKEv2) VPN protocol is a popular choice for Windows 10 Always On VPN deployments. IKEv2 is a standards-based IPsec VPN protocol with customizable security parameters that allows administrators to provide the highest level of protection for remote clients. In addition, it provides important interoperability with a variety of VPN devices, including Microsoft Windows Server Routing and Remote Access Service (RRAS) and non-Microsoft platforms such as Cisco, Checkpoint, Palo Alto, and others.

IKEv2 Limitations

IKEv2 is clearly the protocol of choice in terms of security. It supports modern cryptography and is highly resistant to interception. It’s not without some operational challenges, however. Consider the following.

Firewalls

IKEv2 uses UDP ports 500 and 4500 for communication. Unfortunately, these ports are not always open. Often, they are blocked by network administrators to prevent users from bypassing security controls or attackers from exfiltrating data.

Fragmentation

IKEv2 packets can become quite large at times, especially when using client certificate authentication with the Protected Extensible Authentication Protocol (PEAP). This can result in fragmentation occurring at the network layer. Unfortunately, many firewalls and network devices are configured to block IP fragments by default. This can result in failed connection attempts from some locations but not others.

Load Balancing

Load balancing IKEv2 connections is not entirely straightforward. Without special configuration, load balancers can cause intermittent connectivity issues for Always On VPN connections. Guidance for configuring IKEv2 load balancing on the Kemp LoadMaster and the F5 BIG-IP can be found here:

IKEv2 Fragmentation

IKEv2 fragmentation can be enabled to avoid IP fragmentation and restore reliable connectivity. IKEv2 fragmentation is supported in Windows 10 and Windows Server beginning with v1803. Guidance for enabling IKEv2 fragmentation on Windows Server RRAS can be found here. Support for IKEv2 fragmentation on non-Microsoft firewall/VPN devices is vendor-specific. Consult with your device manufacturer for more information.

IKEv2 Security and RRAS

Be advised that the default security settings for IKEv2 on Windows Server RRAS are very poor. The minimum recommended security settings and guidelines for implementing them can be found here.

IKEv2 or TLS?

IKEv2 is recommend for deployments where the highest level of security and protection is required for remote connections. In these scenarios, the sacrifice of ubiquitous availability in favor of ultimate security might be desired.

SSTP or another TLS-based VPN protocol is recommended if reliable operation and connectivity are desired. SSTP and TLS VPNs can be configured to provide very good security by following the security and implementation guidelines found here.

IKEv2 with TLS Fallback

In theory, preferring IKEv2 and falling back to the Secure Socket Tunneling Protocol (SSTP) or another TLS-based VPN protocol when IKEv2 is unavailable would seem like a logical choice. This would ensure the highest level of protection, while still providing reliable connectivity. Unfortunately, the Windows VPN client doesn’t work this way in practice. Details here.

Additional Information

Windows 10 Always On VPN IKEv2 Load Balancing with F5 BIG-IP

Windows 10 Always On VPN IKEv2 Load Balancing with Kemp LoadMaster

Windows 10 Always On VPN IKEv2 Fragmentation

Windows 10 Always On VPN IKEv2 and SSTP Fallback

Windows 10 Always On VPN IKEv2 Security Configuration

Windows 10 Always On VPN Certificate Requirements for IKEv2

Windows 10 Always On VPN Protocol Recommendations for Windows Server RRAS

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 IKEv2 Load Balancing with KEMP LoadMaster

Always On VPN IKEv2 Load Balancing with KEMP LoadMasterIKEv2 is an IPsec-based VPN protocol with configurable security parameters that allows administrators to ensure the highest level of security for Windows 10 Always On VPN clients. It is the protocol of choice for deployments that require the best possible protection for communication between remote clients and the VPN server. IKEv2 has some unique requirements when it comes to load balancing, however. Because it uses UDP on multiple ports, configuring the load balancer requires some additional steps for proper operation. This article demonstrates how to enable IKEv2 load balancing using the KEMP LoadMaster load balancer.

IKEv2 and NAT

IKEv2 VPN security associations (SAs) begin with a connection to the VPN server that uses UDP port 500. During this initial exchange, if it is determined that the client, server, or both are behind a device performing Network Address Translation (NAT), the connection switches to UDP port 4500 and the connection establishment process continues.

IKEv2 Load Balancing Challenges

Since UDP is connectionless, there’s no guarantee that when the conversation switches from UDP 500 to UDP 4500 that the load balancer will forward the request to the same VPN server on the back end. If the load balancer forwards the UDP 500 session from a VPN client to one real server, then forwards the UDP 4500 session to a different VPN server, the connection will fail. The load balancer must be configured to ensure that both UDP 500 and 4500 from the same VPN client are always forwarded to the same real server to ensure proper operation.

Port Following

To meet this unique requirement for IKEv2 load balancing, it is necessary to use a feature on the KEMP LoadMaster load balancer called “port following”. Enabling this feature will ensure that a VPN client using IKEv2 will always have their UDP 500 and 4500 sessions forwarded to the same real server.

Load Balancing IKEv2

Open the web-based management console and perform the following steps to enable load balancing of IKEv2 traffic on the KEMP LoadMaster load balancer.

Create the Virtual Server

  1. Expand Virtual Services.
  2. Click Add New.
  3. Enter the IP address to be used by the virtual server in the Virtual Address field.
  4. Enter 500 in the Port field.
  5. Select UDP from the Protocol drop-down list.
  6. Click Add this Virtual Service.

Always On VPN IKEv2 Load Balancing with KEMP LoadMaster

Add Real Servers

  1. Expand Real Servers.
  2. Click Add New.
  3. Enter the IP address of the VPN server in the Real Server Address field.
  4. Click Add This Real Server.
  5. Repeat the steps above for each VPN server in the cluster.

Always On VPN IKEv2 Load Balancing with KEMP LoadMaster

Repeat all the steps above to create another virtual server using UDP port 4500.

Always On VPN IKEv2 Load Balancing with KEMP LoadMaster

Enable Layer 7 Operation

  1. Click View/Modify Services below Virtual Services in the navigation tree.
  2. Select the first virtual server and click Modify.
  3. Expand Standard Options.
  4. Uncheck Force L4.
  5. Select Source IP Address from the Persistence Options drop-down list.
  6. Choose an appropriate value from the Timeout drop-down list.
  7. Choose an appropriate setting from the Scheduling Method drop-down list.
  8. Click Back.
  9. Repeat these steps on the second virtual server.

Always On VPN IKEv2 Load Balancing with KEMP LoadMaster

Enable Port Following

  1. Click View/Modify Services below Virtual Services in the navigation tree.
  2. Select the first virtual server and click Modify.
  3. Expand Advanced Properties.
  4. Select the virtual server using UDP 500 from the Port Following drop-down list.
  5. Click Back.
  6. Repeat these steps on the second virtual server.

Always On VPN IKEv2 Load Balancing with KEMP LoadMaster

Demonstration Video

The following video demonstrates how to enable IKEv2 load balancing for Windows 10 Always On VPN using the KEMP LoadMaster Load Balancer.

Summary

With the KEMP LoadMaster load balancer configured to use port following, Windows 10 Always On VPN clients using IKEv2 will be assured that their connections will always be delivered to the same back end VPN server, resulting in reliable load balancing for IKEv2 connections.

Additional Information

Windows 10 Always On VPN Certificate Requirements for IKEv2

Windows 10 Always On VPN Protocol Recommendations for Windows Server RRAS

KEMP LoadMaster Load Balancer Certificate Format Invalid

When implementing a KEMP LoadMaster load balancer, one of the first configuration tasks performed is importing root and intermediate Certification Authority (CA) certificates. When doing this, it is not uncommon to encounter the following error message.

Certificate Format Invalid.

KEMP LoadMaster Load Balancer Certificate Invalid

To resolve this issue, .CER files must first be converted to .PEM format before being imported in to the LoadMaster. Using OpenSSL, .CER files can quickly be converted to .PEM with the following command.

openssl x509 -inform der -in example.cer -out example.pem

Optionally, .CER files can be converted to .PEM online here.

If the root and/or intermediate certificates are from an internal PKI, export the certificates using the Base-64 encoded x.509 (.CER) option. Certificates exported using this format can be imported directly in to the LoadMaster without first having to be converted to .PEM.

KEMP LoadMaster Load Balancer Certificate Format Invalid

Pro tip: When entering the Certificate Name, it is not necessary to enter a file extension. The name will be appended with .PEM automatically upon import.

KEMP LoadMaster Load Balancer Certificate Format Invalid

KEMP LoadMaster Load Balancer Certificate Format Invalid

Additional Resources

DirectAccess Deployment Guide for KEMP LoadMaster Load Balancers

Maximize Your Investment in Windows 10 with KEMP LoadMaster Load Balancers

DirectAccess and the FREE KEMP LoadMaster Load Balancer

Configure KEMP LoadMaster Load Balancer for DirectAccess Network Location Server (NLS)

Planning and Implementing DirectAccess Video Training Course on Pluralsight

Implementing DirectAccess with Windows Server 2016 Book

DirectAccess Load Balancing Tips and Tricks Webinar

KEMP Technologies LoadMaster Load BalancerEnabling load balancing for DirectAccess deployments is crucial for eliminating single points of failure and ensuring the highest levels of availability for the remote access solution. In addition, enabling load balancing allows DirectAccess administrators to quickly and efficiently add capacity in the event more processing power is required.

DirectAccess includes support for load balancing using integrated Windows Network Load Balancing (NLB) and external load balancers (physical or virtual). External load balancers are the recommended choice as they provide superior throughput, more granular traffic distribution, and greater visibility. External load balancers also more scalable, with support for much larger DirectAccess server clusters, up to 32 nodes. NLB is formally limited to 8 nodes, but because it operates at layer 2 in the OSI model and relies on broadcast heartbeat messages, it is effectively limited to 4 nodes.

The KEMP Technologies LoadMaster load balancer is an excellent choice for load balancing the DirectAccess workload. To learn more about configuring the LoadMaster with DirectAccess, join me for a free live webinar on Tuesday, August 16 at 10:00AM PDT where I’ll discuss DirectAccess load balancing in detail. I will also be sharing valuable tips, tricks, and best practices for load balancing DirectAccess.

DirectAccess Load Balancing Tips and Tricks Webinar

Don’t miss out. Register today!

Additional Resources

DirectAccess Load Balancing Overview

Load Balancing DirectAccess with the KEMP Loadmaster Load Balancer

Maximize your investment in Windows 10 with DirectAccess and the KEMP LoadMaster Load Balancer

KEMP LoadMaster DirectAccess Deployment Guide

DirectAccess Multisite Geographic Redundancy with Microsoft Azure Traffic Manager

Introduction

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

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

Challenges

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

GSLB

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

Azure Traffic Manager

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

DirectAccess Multisite Geographic Redundancy with Microsoft Azure Traffic Manager

Traffic Manager Configuration

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

DirectAccess Multisite Geographic Redundancy with Microsoft Azure Traffic Manager

Provide a name and select a Routing method.

DirectAccess Multisite Geographic Redundancy with Microsoft Azure Traffic Manager

Routing method options are Performance, Weighted and Priority.

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

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

DirectAccess Multisite Geographic Redundancy with Microsoft Azure Traffic Manager

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

DirectAccess Multisite Geographic Redundancy with Microsoft Azure Traffic Manager

DirectAccess Configuration

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

DirectAccess Multisite Geographic Redundancy with Microsoft Azure Traffic Manager

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

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

DirectAccess Multisite Geographic Redundancy with Microsoft Azure Traffic Manager

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

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

For example:

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

Summary

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

Additional Resources

 

 

 

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