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 and NAT

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 Load Balancing for RRAS in Azure

Always On VPN Load Balancing for RRAS in AzurePreviously I wrote about Always On VPN options for Microsoft Azure deployments. In that post I indicated that running Windows Server with the Routing and Remote Access Service (RRAS) role for VPN was an option to be considered, even though it is not a formally supported workload. Despite the lack of support by Microsoft, deploying RRAS in Azure works well and is quite popular. In fact, I recently published some configuration guidance for RRAS in Azure.

Load Balancing Options for RRAS

Multiple RRAS servers can be deployed in Azure to provide failover/redundancy or to increase capacity. While Windows Network Load Balancing (NLB) can be used on-premises for RRAS load balancing, NLB is not supported and doesn’t work in Azure. With that, there are several options for load balancing RRAS in Azure. They include DNS round robin, Azure Traffic Manager, the native Azure load balancer, Azure Application Gateway, or a dedicated load balancing virtual appliance.

DNS Round Robin

The easiest way to provide load balancing for RRAS in Azure is to use round robin DNS. However, using this method has some serious limitations. Simple DNS round robin can lead to connection attempts to a server that is offline. In addition, this method doesn’t accurately balance the load and often results in uneven distribution of client connections.

Azure Traffic Manager

Using Azure Traffic Manager is another alternative for load balancing RRAS in Azure. In this scenario each VPN server will have its own public IP address and FQDN for which Azure Traffic Manager will intelligently distribute traffic. Details on configuring Azure Traffic Manager for Always On VPN can be found here.

Azure Load Balancer

The native Azure load balancer can be configured to provide load balancing for RRAS in Azure. However, it has some serious limitations. Consider the following.

  • Supports Secure Socket Tunneling Protocol (SSTP) only.
  • Basic health check functionality (port probe only).
  • Limited visibility.
  • Does not work with IKEv2.
  • Does not support TLS offload for SSTP.

More information about the Azure Load Balancer can be found here.

Azure Application Gateway

The Azure Application Gateway can be used for load balancing RRAS SSTP VPN connections where advanced capabilities such as enhanced health checks and TLS offload are required. More information about the Azure Application Gateway can be found here.

Load Balancing Appliance

Using a dedicated Application Delivery Controller (ADC), or load balancer is a very effective way to eliminate single points of failure for Always On VPN deployments hosted in Azure. ADCs provide many advanced features and capabilities to ensure full support for all RRAS VPN protocols. In addition, ADCs offer much better visibility and granular control over VPN connections. There are many solutions available as virtual appliances in the Azure marketplace that can be deployed to provide RRAS load balancing in Azure.

Summary

Deploying Windows Server RRAS in Azure for Always On VPN can be a cost-effective solution for many organizations. Although not a formally supported workload, I’ve deployed it numerous times and it works quite well. Consider using a dedicated ADC to increase scalability or provide failover and redundancy for RRAS in Azure whenever possible.

Additional Information

Windows 10 Always On VPN Options for Azure Deployments

Windows 10 Always On VPN and RRAS in Microsoft Azure

Windows 10 Always On VPN with Microsoft Azure Gateway