To deploy a firewall to subnetl-2, you need to create a network virtual appliance (NVA) in the same virtual network as subnetl-2. An NVA is a virtual machine that performs network functions, such as firewall, routing, or load balancing1.

To create an NVA, you need to create a virtual machine in the Azure portal and select an image that has the firewall software installed. You can choose from the Azure Marketplace or upload your own image2.

To assign the IP address of 10.1.2.4 to the NVA, you need to create a static private IP address for the network interface of the virtual machine. You can do this in the IP configurations settings of the network interface3.

To ensure that traffic from subnetl-1 to the IP address range of 192.168.10.0/24 is routed through the NVA, you need to create a user-defined route (UDR) table and associate it with subnetl-1. A UDR table allows you to override the default routing behavior of Azure and specify custom routes for your subnets4.

To create a UDR table, you need to go to the Route tables service in the Azure portal and select + Create. You can give a name and a resource group for the route table5.

To create a custom route, you need to select Routes in the route table and select + Add. You can enter the following information for the route5:

Destination: 192.168.10.0/24

Next hop type: Virtual appliance

Next hop address: 10.1.2.4

To associate the route table with subnetl-1, you need to select Subnets in the route table and select + Associate. You can select the virtual network and subnet that you want to associate with the route table5.