How to create a NAT Switch in HYPER-V

Sometimes might need to isolate specific VMs but allow them to have access to the Internet.

We know that if we want to isolate a VM we can use a Private Virtual Switch in HYPER-V. This solution has the disadvantage that the VM will not have an Internet connection. (include the containers)

Today I will explain how can use a NAT Network with a HYPER-V Switch.

What is NAT

I will try to give a simple explanation of what is a NAT.

NAT It's a technology that maps an external IP Address and a port to an Internal IP Address to a much largest set of IP addresses.

The most common example of NAT is the translation of the Public IP Address from a home router to multiple internal or private IP Addresses (Laptops, mobiles, TV).

Today I will explain how can use a NAT Network in HYPER-V.

We will create a NAT Switch that will provide Internet access to multiple VMs from the Host Network Adapter.

How to create a NAT Network in HYPER-V

NAT Switch can use it from Windows Server 2016 and after. It's not supported in Windows Server 2012.

We can't create a NAT Switch from HYPER-V Manager but only with PowerShell commands.

So let's take a look at how can do it.

Open PowerShell as Administrator
Run the below command to create the Virtual Switch in HYPER-V
New-VMSwitch -SwitchName "NATSwitch"-SwitchTyper Internal

You can see the Virtual Switch from the HYPER-V Manager as well.

Now run the below command to get the Index Number of the Virtual Switch Interface. Will be used to give an IP address on the specific Interface.
Get-NetAdapater

We will run the following to give an IP Address to the NATSwitch. This IP Address will be used as a Gateway in the VMs
You must have decided the IP Range that will give to the VMs
New-NetIPAddress -IPAdress 192.168.60.254 -PrefixLength 24 -InterfaceAlias "vEthernet(NAT")

Now we can create the NAT in the NATSwitch.
New-NetNat -Name "NatSwitch" -InternalIPInterfaceAddressPrefix 192.168.60.0/24

Open the HYPER-V Manager and select the VM that you want to use the NAT Network
Click Settings.
Select the Network Adapter. From the right side in the Virtual Switch select the Switch that we created before.

HYPERV Virtual machine network adapter settings

Now login to the Virtual Machine.
Click Start and type Ethernet Settings.
Click on Ethernet Settings.
From the left side select Change adapter options.

Right click on the Interface and select Properties.
Click on Internet Protocol Version 4 and select Properties.

Configure the IP Address in the range of the NAT Network.
The default Gateway will be the IP Address that gave in the NAT Switch.
Configure your DNS Servers and click OK.

Now the VM should has access to the Internet but will not communicate with the HYPER-V Host.
In case that you can't connect in the Internet, check the routing with the route print command to verify that all the traffic goes to the Default Gateway.

If you will see more that one routes in the Persistent Routes then use the route delete to delete the routing and add again the Default Gateway.
The route delete command can use it like route delete 0.0.0.0 192.168.60.254