Set up Active/Passive HA on Azure

Set up the VM-Series firewall on Azure in a high availability set up using the VM-Series plugin.

With the VM-Series Plugin, you can configure a pair of VM-Series firewalls on Azure in an active/passive high availability (HA) configuration. For HA on Azure, you must deploy both firewall HA peers within the same Azure Resource Group.

To ensure uptime in an HA setup on Azure, you need floating IP addresses that can quickly move from one peer to the other. Because you cannot move the IP address associated with the primary interface of the firewall on Azure, you need to assign a secondary IP address that can function as a floating IP address. When the active firewall goes down, the floating IP address moves from the active to the passive firewall so that the passive firewall can seamlessly secure traffic as soon as it becomes the active peer. In addition to the floating IP address, the HA peers also need HA links—a control link (HA1) and a data link (HA2)—to synchronize data and maintain state information.

Set up Active/Passive HA on Azure
Set up the Firewalls for Enabling HA
Configure Active/Passive HA on the VM-Series Firewall on Azure

Set up the Firewalls for Enabling HA

Gather the following details for configuring HA on the VM-Series firewalls on Azure.

Set up the Active Directory application and a Service Principal to enable programmatic API access.
- For the firewall to interact with the Azure APIs, you need to create an Azure Active Directory Service Principal. This Service Principle has the permissions required to authenticate to the Azure AD and access the resources within your subscription.To complete this set up, you must have permissions to register an application with your Azure AD tenant, and assign the application to a role in your subscription. If you don't have the necessary permissions, ask your Azure AD or subscription administrator to create a Service Principal with an IAM role of contributor. Copy the following details for use later in this workflow:
  - Client ID—The Application ID associated with the Active Directory (Azure Active DirectoryApp registrations, select your application and copy the ID).
  - Tenant ID—The Directory ID (Azure Active DirectoryPropertiesDirectory ID on the Azure portal).
  - Azure Subscription ID—The Azure subscription in which you have deployed the firewalls. You must login to your Azure portal to get this subscription ID.
  - Resource Group Name— The resource group name in which you have deployed the firewalls that you want to configure as HA peers. Both firewalls must be in the same resource group.
  - Secret Key—The authentication key associated with the Active Directory application. To log in as the application, you must provide both the key value and the Application ID.
Know where to get the templates you need to deploy the VM-Series firewalls within the same Azure Resource Group.
For an HA configuration, both HA peers must belong to the same Azure Resource Group. If you deploy the first instance of the firewall from the Azure Marketplace, and must use your custom ARM template or the Palo Alto Networks sample GitHub template for deploying the second instance of the firewall into the existing Resource Group. The reason you need a custom template or the Palo Alto Networks sample template is because Azure does not support the ability to deploy the firewall in to an Resource Group that is not empty.

Copy the deployment information for the first firewall instance. For example:

Plan the network interface configuration on the VM-Series firewalls on Azure.

To set up HA, you must deploy both HA peers within the same Azure Resource Group and both firewalls must have the same number of network interfaces. A minimum of four network interfaces is required on each HA peer:

Management interface (eth0)—Private and public IP address associated with the primary interface. The public IP address enables access to the firewall web interface and SSH access.
You can use the private IP interface on the management interface as the HA1 peer IP address for the control link communication between the active/passive HA peers. If you want a dedicated HA1 interface, you must attach an additional network interface on each firewall, and this means that you need five interfaces on each firewall.
Untrust interface (eth1/1)—Primary private IP address with /32 netmask, and secondary IP configuration with both a private IP address (any netmask) and a public IP address.
On failover, when the passive peer transitions to the active state, the public IP address associated with the secondary IP configuration is detached from the previously active peer and attached to the now active HA peer.
Trust interface (eth1/2)—Primary and secondary private IP addresses. On failover, when the passive peer transitions to the active state, the secondary private IP address is detached from the previously active peer and is attached to the now active HA peer.
HA2 (eth 1/3)—Primary private IP address. The HA2 interface is the data link that the HA peers use for synchronizing sessions, forwarding tables, IPSec security associations and ARP tables.

Interface	Active firewall peer	Passive firewall peer	Description
Trust	Secondary IP address	—	The trust interface of the active peer requires a secondary IP configuration that can float to the other peer on failover. This secondary IP configuration on the trust interface must be a private IP address with the netmask of the servers that it secures. On failover, the VM-Series plugin calls the Azure API to detach this secondary private IP address from the active peer and attach it to the passive peer. Attaching this IP address to the now active peer ensures that the firewall can receive traffic on the floating IP on the untrust interface and send it through to the floating IP on the trust interface and on to the workloads.
Untrust	Secondary IP address	—	The untrust interface of the firewall requires a secondary IP configuration that includes a static private IP address with a netmask for the untrust subnet, and a public IP address for accessing the back-end servers or workloads over the internet. On failover, the VM-Series plugin calls the Azure API to detach the secondary IP configuration from the active peer and attach it to the passive peer before it transitions to the active state. This process of floating the secondary IP configuration, enables the now active firewall to continue processing inbound traffic that is destined to the workloads.
HA2	Add a NIC to the firewall from the Azure management console.	Add a NIC to the firewall from the Azure management console.	On the active and passive peers, add a dedicated HA2 link to enable session synchronization. The default interface for HA1 is the management interface, and you can opt to use the management interface instead of adding an additional interface to the firewall. For enabling data flow over the HA2 link, you need to add an additional network interface on the Azure portal and configure the interface for HA2 on the firewall.

Configure Active/Passive HA on the VM-Series Firewall on Azure

In this workflow, you deploy the first instance of the VM-Series firewall using the VM-Series firewall solution template in the Azure marketplace, and the second instance of the firewall using the sample GitHub template.

Deploy the VM-Series firewall using the Solution template and set up the network interfaces for HA.
1. Add a secondary IP configuration to the untrust interface of the firewall.
  
  You must attach the secondary IP configuration—with a private IP address (any netmask) and a public IP address—to the firewall that will be designated as the active peer. The secondary IP configuration always stays with the active HA peer, and moves from one peer to the another when a failover occurs.
  In this workflow, this firewall will be designated as the active peer. The active HA peer has a lower numerical value for device priority that you configure as a part of the HA configuration on the firewall, and this value indicates a preference for which firewall assumes the role of the active peer.
2. Add a secondary IP configuration to the trust interface of the firewall.
  
  The secondary IP configuration for the trust interface requires a static private IP address only. This IP address moves from the active firewall to the passive firewall on failover so that traffic flows through from the untrust to the trust interface and to the destination subnets that the firewall secures.
3. Attach a network interface for the HA2 communication between the firewall HA peers.
  1. Add a subnet within the virtual network.
  2. Create and attach a network interface to the firewall.
Configure the interfaces on the firewall.
Complete these steps on the active HA peer, before you deploy and set up the passive HA peer.
1. Log in to the firewall web interface.
2. Configure ethernet 1/1 as the untrust interface and ethernet 1/2 as the untrust interface.
  Select NetworkInterfaces and configure as follows:
3. Configure ethernet 1/3 as the HA interface.
  To set up the HA2 link, select the interface and set Interface Type to HA. Set link speed and duplex to auto.
Configure the VM-Series plugin to authenticate to the Azure resource group in which you have deployed the firewall.
Set up the Azure HA configuration on the VM-Series plugin.
1. Select DeviceVM-Series to enable programmatic access between the firewall plugin and the Azure resources.
2. Enter the Client ID. The client ID is the Application ID associated with your Azure Active Directory application.
3. Enter the Subscription ID for the Azure subscription you want to monitor.
4. Enter the Client Secret and re-enter it to confirm.
5. Enter the Tenant ID. The tenant ID is the Directory ID you saved when you set up the Active Directory application.
6. Click Validate to verify that the keys and IDs you entered are valid, and that VM-Series plugin can successfully communicate with the Azure resources using the API.
Enable HA.
1. Select DeviceSetupHA.
2. Enter Peer HA1 IP address as the private IP address of the passive peer.
3. (Optional) Edit the Control Link (HA1). If you do not plan to use the management interface for the control link and have added an additional interface (for example ethernet 1/4), edit this section to select the interface to use for HA1 communication.
4. Edit the Data Link (HA2) to use Port ethernet 1/3 and add the IP address of this peer and the Gateway IP address for the subnet.
Commit the changes.
Set up the passive HA peer within the same Azure Resource Group.
1. Deploy the second instance of the firewall.
  - Download the custom template and parameters file from GitHub.
  - Log in to the Azure Portal.
  - Search for custom template and select Deploy from a custom template.
  - Select Build your own template in the editorLoad file.
  - Select the azuredeploy.json that you downloaded earlier, and Save.
  - Complete the inputs, agree to the terms and Purchase.
    Make sure to match the following inputs to that of the firewall instance you have already deployed— Azure subscription, name of the Resource Group, location of the Resource Group, name of the existing VNet into which you want to deploy the firewall, VNet CIDR, Subnet names, Subnet CIDRs, and start the IP address for the management, trust and untrust subnets.
2. Repeat Step 1and Step 2to set up the interfaces and configure the firewall as the passive HA peer.
3. Skip Step 3 and complete Enable HA (Step 5). In Step 4 modify the IP addresses as appropriate for this passive HA peer.
After you finish configuring both firewalls, verify that the firewalls are paired in active/passive HA.
1. Access the Dashboard on both firewalls, and view the High Availability widget.
2. On the active firewall, click the Sync to peer link.
3. Confirm that the firewalls are paired and synced, as shown as follows:
  - On the passive firewall: the state of the local firewall should display passive and the Running Config should show as synchronized.
  - On the active firewall: The state of the local firewall should display active and the Running Config should show as synchronized.
4. On the passive peer, verify that the VM-Series plugin configuration is now synced.
  Select DeviceVM-Series and validate that you can view the Azure HA configuration that you had omitted configuring on the passive peer.