Quickstart: Secure your virtual hub using Azure Firewall Manager - Bicep

Article
03/08/2023

In this quickstart, you use Bicep to secure your virtual hub using Azure Firewall Manager. The deployed firewall has an application rule that allows connections to www.microsoft.com . Two Windows Server 2019 virtual machines are deployed to test the firewall. One jump server is used to connect to the workload server. From the workload server, you can only connect to www.microsoft.com.

Bicep is a domain-specific language (DSL) that uses declarative syntax to deploy Azure resources. It provides concise syntax, reliable type safety, and support for code reuse. Bicep offers the best authoring experience for your infrastructure-as-code solutions in Azure.

For more information about Azure Firewall Manager, see What is Azure Firewall Manager?.

Prerequisites

An Azure account with an active subscription. Create an account for free.

Review the Bicep file

This Bicep file creates a secured virtual hub using Azure Firewall Manager, along with the necessary resources to support the scenario.

The Bicep file used in this quickstart is from Azure Quickstart Templates.

@description('Admin username for the servers')
param adminUsername string

@description('Password for the admin account on the servers')
@secure()
param adminPassword string

@description('Location for all resources.')
param location string = resourceGroup().location

@description('Size of the virtual machine.')
param vmSize string = 'Standard_D2_v3'

resource virtualWan 'Microsoft.Network/virtualWans@2021-08-01' = {
  name: 'VWan-01'
  location: location
  properties: {
    disableVpnEncryption: false
    allowBranchToBranchTraffic: true
    type: 'Standard'
  }
}

resource virtualHub 'Microsoft.Network/virtualHubs@2021-08-01' = {
  name: 'Hub-01'
  location: location
  properties: {
    addressPrefix: '10.1.0.0/16'
    virtualWan: {
      id: virtualWan.id
    }
  }
}

resource hubVNetconnection 'Microsoft.Network/virtualHubs/hubVirtualNetworkConnections@2021-08-01' = {
  parent: virtualHub
  name: 'hub-spoke'
  dependsOn: [
    firewall
  ]
  properties: {
    remoteVirtualNetwork: {
      id: virtualNetwork.id
    }
    allowHubToRemoteVnetTransit: true
    allowRemoteVnetToUseHubVnetGateways: false
    enableInternetSecurity: true
    routingConfiguration: {
      associatedRouteTable: {
        id: hubRouteTable.id
      }
      propagatedRouteTables: {
        labels: [
          'VNet'
        ]
        ids: [
          {
            id: hubRouteTable.id
          }
        ]
      }
    }
  }
}

resource policy 'Microsoft.Network/firewallPolicies@2021-08-01' = {
  name: 'Policy-01'
  location: location
  properties: {
    threatIntelMode: 'Alert'
  }
}

resource ruleCollectionGroup 'Microsoft.Network/firewallPolicies/ruleCollectionGroups@2021-08-01' = {
  parent: policy
  name: 'DefaultApplicationRuleCollectionGroup'
  properties: {
    priority: 300
    ruleCollections: [
      {
        ruleCollectionType: 'FirewallPolicyFilterRuleCollection'
        name: 'RC-01'
        priority: 100
        action: {
          type: 'Allow'
        }
        rules: [
          {
            ruleType: 'ApplicationRule'
            name: 'Allow-msft'
            sourceAddresses: [
              '*'
            ]
            protocols: [
              {
                port: 80
                protocolType: 'Http'
              }
              {
                port: 443
                protocolType: 'Https'
              }
            ]
            targetFqdns: [
              '*.microsoft.com'
            ]
          }
        ]
      }
    ]
  }
}

resource firewall 'Microsoft.Network/azureFirewalls@2021-08-01' = {
  name: 'AzfwTest'
  location: location
  properties: {
    sku: {
      name: 'AZFW_Hub'
      tier: 'Standard'
    }
    hubIPAddresses: {
      publicIPs: {
        count: 1
      }
    }
    virtualHub: {
      id: virtualHub.id
    }
    firewallPolicy: {
      id: policy.id
    }
  }
}

resource virtualNetwork 'Microsoft.Network/virtualNetworks@2021-08-01' = {
  name: 'Spoke-01'
  location: location
  properties: {
    addressSpace: {
      addressPrefixes: [
        '10.0.0.0/16'
      ]
    }
    enableDdosProtection: false
    enableVmProtection: false
  }
}

resource subnet_Workload_SN 'Microsoft.Network/virtualNetworks/subnets@2021-08-01' = {
  parent: virtualNetwork
  name: 'Workload-SN'
  properties: {
    addressPrefix: '10.0.1.0/24'
    privateEndpointNetworkPolicies: 'Enabled'
    privateLinkServiceNetworkPolicies: 'Enabled'
  }
}

resource subnet_Jump_SN 'Microsoft.Network/virtualNetworks/subnets@2021-08-01' = {
  parent: virtualNetwork
  name: 'Jump-SN'
  dependsOn: [
    subnet_Workload_SN
  ]
  properties: {
    addressPrefix: '10.0.2.0/24'
    routeTable: {
      id: routeTable.id
    }
    privateEndpointNetworkPolicies: 'Enabled'
    privateLinkServiceNetworkPolicies: 'Enabled'
  }
}

resource Jump_Srv 'Microsoft.Compute/virtualMachines@2022-03-01' = {
  name: 'Jump-Srv'
  location: location
  properties: {
    hardwareProfile: {
      vmSize: vmSize
    }
    storageProfile: {
      imageReference: {
        publisher: 'MicrosoftWindowsServer'
        offer: 'WindowsServer'
        sku: '2019-Datacenter'
        version: 'latest'
      }
      osDisk: {
        osType: 'Windows'
        createOption: 'FromImage'
        caching: 'ReadWrite'
        managedDisk: {
          storageAccountType: 'StandardSSD_LRS'
        }
        diskSizeGB: 127
      }
    }
    osProfile: {
      computerName: 'Jump-Srv'
      adminUsername: adminUsername
      adminPassword: adminPassword
      windowsConfiguration: {
        provisionVMAgent: true
        enableAutomaticUpdates: true
      }
      allowExtensionOperations: true
    }
    networkProfile: {
      networkInterfaces: [
        {
          id: netInterface_jump_srv.id
        }
      ]
    }
  }
}

resource Workload_Srv 'Microsoft.Compute/virtualMachines@2022-03-01' = {
  name: 'Workload-Srv'
  location: location
  properties: {
    hardwareProfile: {
      vmSize: vmSize
    }
    storageProfile: {
      imageReference: {
        publisher: 'MicrosoftWindowsServer'
        offer: 'WindowsServer'
        sku: '2019-Datacenter'
        version: 'latest'
      }
      osDisk: {
        osType: 'Windows'
        createOption: 'FromImage'
        caching: 'ReadWrite'
        managedDisk: {
          storageAccountType: 'StandardSSD_LRS'
        }
        diskSizeGB: 127
      }
    }
    osProfile: {
      computerName: 'Workload-Srv'
      adminUsername: adminUsername
      adminPassword: adminPassword
      windowsConfiguration: {
        provisionVMAgent: true
        enableAutomaticUpdates: true
      }
      allowExtensionOperations: true
    }
    networkProfile: {
      networkInterfaces: [
        {
          id: netInterface_workload_srv.id
        }
      ]
    }
  }
}

resource netInterface_workload_srv 'Microsoft.Network/networkInterfaces@2021-08-01' = {
  name: 'netInterface-workload-srv'
  location: location
  properties: {
    ipConfigurations: [
      {
        name: 'ipconfig1'
        properties: {
          privateIPAllocationMethod: 'Dynamic'
          subnet: {
            id: subnet_Workload_SN.id
          }
          primary: true
          privateIPAddressVersion: 'IPv4'
        }
      }
    ]
    enableAcceleratedNetworking: false
    enableIPForwarding: false
    networkSecurityGroup: {
      id: nsg_workload_srv.id
    }
  }
}

resource netInterface_jump_srv 'Microsoft.Network/networkInterfaces@2021-08-01' = {
  name: 'netInterface-jump-srv'
  location: location
  properties: {
    ipConfigurations: [
      {
        name: 'ipconfig1'
        properties: {
          privateIPAllocationMethod: 'Dynamic'
          publicIPAddress: {
            id: publicIP_jump_srv.id
          }
          subnet: {
            id: subnet_Jump_SN.id
          }
          primary: true
          privateIPAddressVersion: 'IPv4'
        }
      }
    ]
    enableAcceleratedNetworking: false
    enableIPForwarding: false
    networkSecurityGroup: {
      id: nsg_jump_srv.id
    }
  }
}

resource nsg_jump_srv 'Microsoft.Network/networkSecurityGroups@2021-08-01' = {
  name: 'nsg-jump-srv'
  location: location
  properties: {
    securityRules: [
      {
        name: 'RDP'
        properties: {
          protocol: 'Tcp'
          sourcePortRange: '*'
          destinationPortRange: '3389'
          sourceAddressPrefix: '*'
          destinationAddressPrefix: '*'
          access: 'Allow'
          priority: 300
          direction: 'Inbound'
        }
      }
    ]
  }
}

resource nsg_workload_srv 'Microsoft.Network/networkSecurityGroups@2021-08-01' = {
  name: 'nsg-workload-srv'
  location: location
  properties: {}
}

resource publicIP_jump_srv 'Microsoft.Network/publicIPAddresses@2021-08-01' = {
  name: 'publicIP-jump-srv'
  location: location
  sku: {
    name: 'Standard'
  }
  properties: {
    publicIPAddressVersion: 'IPv4'
    publicIPAllocationMethod: 'Static'
    idleTimeoutInMinutes: 4
  }
}

resource routeTable 'Microsoft.Network/routeTables@2021-08-01' = {
  name: 'RT-01'
  location: location
  properties: {
    disableBgpRoutePropagation: false
    routes: [
      {
        name: 'jump-to-inet'
        properties: {
          addressPrefix: '0.0.0.0/0'
          nextHopType: 'Internet'
        }
      }
    ]
  }
}

resource hubRouteTable 'Microsoft.Network/virtualHubs/hubRouteTables@2021-08-01' = {
  parent: virtualHub
  name: 'RT_VNet'
  properties: {
    routes: [
      {
        name: 'Workload-SNToFirewall'
        destinationType: 'CIDR'
        destinations: [
          '10.0.1.0/24'
        ]
        nextHopType: 'ResourceId'
        nextHop: firewall.id
      }
      {
        name: 'InternetToFirewall'
        destinationType: 'CIDR'
        destinations: [
          '0.0.0.0/0'
        ]
        nextHopType: 'ResourceId'
        nextHop: firewall.id
      }
    ]
    labels: [
      'VNet'
    ]
  }
}

Multiple Azure resources are defined in the Bicep file:

Deploy the Bicep file

Save the Bicep file as main.bicep to your local computer.

Deploy the Bicep file using either Azure CLI or Azure PowerShell.

CLI
PowerShell

az group create --name exampleRG --location eastus
az deployment group create --resource-group exampleRG --template-file main.bicep --parameters adminUsername=<admin-user>

New-AzResourceGroup -Name exampleRG -Location eastus
New-AzResourceGroupDeployment -ResourceGroupName exampleRG -TemplateFile ./main.bicep -adminUsername "<admin-user>"

Note

Replace <admin-user> with the administrator login username for the servers. You'll be prompted to enter adminPassword.

When the deployment finishes, you should see a message indicating the deployment succeeded.

Validate the deployment

Use Azure CLI or Azure PowerShell to review the deployed resources.

CLI
PowerShell

az resource list --resource-group exampleRG

Get-AzResource -ResourceGroupName exampleRG

Now, test the firewall rules to confirm that it works as expected.

From the Azure portal, review the network settings for the Workload-Srv virtual machine and note the private IP address.
Connect a remote desktop to Jump-Srv virtual machine, and sign in. From there, open a remote desktop connection to the Workload-Srv private IP address.
Open Internet Explorer and browse to www.microsoft.com.
Select OK > Close on the Internet Explorer security alerts.

You should see the Microsoft home page.
Browse to www.google.com.

You should be blocked by the firewall.

Now you've verified that the firewall rules are working, you can browse to the one allowed FQDN, but not to any others.

Clean up resources

When you no longer need the resources that you created with the firewall, use Azure portal, Azure CLI, or Azure PowerShell to delete the resource group. This removes the firewall and all the related resources.

CLI
PowerShell

az group delete --name exampleRG

Remove-AzResourceGroup -Name exampleRG

Next steps

Learn about security partner providers