Another method for traffic control is the inbound NAT rules, which map a public port on the load balancer to a port on a specific virtual machine in the backend address pool.

To add an inbound NAT rule, you have to follow these steps:

1. Navigate to the load balancer; under SETTINGS, click on Inbound NAT rules, and a new blade will be opened, as shown in the following screenshot:

2. To add a new rule, click on Add, and a new blade will pop up, asking you to specify the following:
   • Name: A descriptive name for the rule.
   • Frontend IP address: The frontend IP address is the address through which the clients will communicate, then it will route their traffic to the target VM by this NAT rule.
   • Service: You can scroll down and select one of the many services that are available in the drop-down list; if none of them are suitable for your service, you can select Custom.
   • Protocol: If Custom is selected, you need to specify its type – whether it is TCP or UDP.
   • Port: If custom is selected, you need to manually specify the port.
   • Associated to: Specify whether it is associated with an availability set, a single VM, or a VM scale set.
   • Target virtual machine: The VM that receives the traffic route by this NAT rule, taking into account that VMs must be in the same location as the load balancer.
   • Network IP configuration: The IP configuration that will receive traffic for the chosen virtual machine, taking into account that the IP version of the IP configuration must match the IP version of the frontend IP address.
   • Port mapping: If Default is selected, it will map the port through which the traffic comes to the same port on the VM. If custom is selected, you can manually specify the port to which the traffic will be routed:

3. Once you have clicked on Add, the rule should be added within a couple of minutes.