LAN Routing and NAT with Windows Server 2016

Introduction

In this article I’m setting up a 3 way router with Windows Server 2016, which will be performing LAN routing between two subnets and NAT for both subnets. This setup will replace the gateway I had in my Hyper-V virtual lab. So, basically, I needed to add a new subnet to my virtual lab (10.0.0.32/27) and I needed both subnets to communicate and both to have internet access. I could have done this by adding a router between both subnets, but for that I would need to add a new virtual machine, which would be consuming additional resources from my Hyper-V server. This way, I’ll have a solution that will grow with the virtual lab. In case I need to add a new subnet to the lab, I just have to add a new interface to the router and all subnets will be automatically routed between each other. Perfect!

 

If you are looking to set up a simple NAT router with Windows Server 2016, with one subnet and an internet connection, please read this article instead:

https://www.experiencingit.net/windows/windows-server-2016-nat-router/

My virtual lab

Please note that this is my virtual lab configuration. You will have to configure the router to match your own network config, but, if you are reading this, I assume you already know that. Also, DNS servers are not in place here. After configuring the router, your client PCs will need to have a DNS server configured – usually your internet router – so that they will be able to browse the internet. Again, if you are reading this article I assume you have a basic understanding how these things work.

Virtual Lab

Let’s start

First things first

You will need a machine with Windows Server 2016 installed, for which you can find a guide here, with three network cards attached to it, as per the diagram above.

 

Adding the Remote Access role

  • Open “Server Manager”. Click on the start button and find “Server Manager”.
  • Click on “Add roles and features”.

Nat and Lan Routing With Windows Server 2016 - Add roles and features

 

  • Click “Next” until you reach the “Select server roles” window. Check the “Remote Access” box and click “Next”.

Lan Routing and NAT with Windows Server 2016 - Select server roles

 

NOTE: If you get the message below when adding the “Remote Access” role, just press the “Previous” button and “Next” again, and try again adding the role. This should make that message go away.

Lan Routing and NAT with Windows Server 2016 - version mismatch message

  • Click “Next” until you reach the “Select role services” window.
  • Select “Routing”

LAN Routing and NAT with Windows Server 2016 - Select role services

 

  • Click on “Add Features”

LAN Routing and NAT with Windows Server 2016 - Add role features

 

  • Note that “DirectAccess and VPN (RAS)” are selected by default. No need to make any changes. Press “Next”.

LAN Routing and NAT with Windows Server 2016 - Select role services

 

  • Click on “Install” on the “Confirmation” window and wait for the role to be installed.

LAN Routing and NAT with Windows Server 2016 - Confirmation Remote Access

 

Configuring the Remote Access Role

  • Press the “Start” button and find the “Routing and Remote Access” console. Open it.

LAN Routing and NAT with Windows Server 2016 - RRAS Console on the Start Menu

 

  • Right-click on the (local) server and select “Configure and Enable Routing and Remote Access”

LAN Routing and NAT with Windows Server 2016 - Routing and Remote Access Console

 

  • Press “Next” at the welcome window of the “Routing and Remote Access Server Setup Wizard”.
  • On the “Configuration” window, select “Network address translation (NAT)” and press “Next”.

LAN and NAT Routing with Windows Server 2016 - RRAS Config Window

 

  • Select the public interface that you are using to connect to the internet. Press “Next”.
  • Select the interface that will have access to internet. Select the first interface and press “Next”. We’ll deal with the second interface later.

LAN Routing and NAT with Windows Server 2016 - RRAS Setup choose NAT interface 1

 

  • Click on “Finish” to close the setup wizard. If a pop-up window comes up warning about firewall ports for VPN connections, you can safely ignore this warning as we are not setting up any VPN access. Just press “OK” and wait  for the “Routing and Remote” access service to start.

LAN Routing and NAT with Windows Server 2016 - RRAS Service Starting

 

Adding the second NAT interface

So, during the Routing and Remote Access setup wizard, we’ve configured NAT for one of the subnets, but if we want (and we do!) to provide internet access to another subnet, we must configure NAT for the second (n) interface.

  • On the “Routing and Remote Access” console, under IPv4, right-click “NAT” and select “New Interface…”

LAN Routing and NAT with Windows Server 2016 - RRAS Setup Add New Interface NAT

 

  • Select the interface for the second subnet and press “OK”.

LAN Routing and NAT with Windows Server 2016 - RRAS Setup add second NAT interface

 

  • Select “Private interface connected to private network” and click “OK”

LAN Routing and NAT with Windows Server 2016 - RRAS Setup add NAT interface

 

And this ends setting up the server. Now it’s time to test if all is working as it should!

 

Checking the configuration

In the “Routing and Remote Access” console, under IPv4, right-click “Static Routes” and choose “Show IP Routing Table…”. A new window, with the known routes to this computer, will pop-up. Analyzing that window (please always remember that this IP Routing table is regarding my setup, which is the one described in the diagram on the top of the page), you will see that we have:

1 – A gateway! All traffic that the router doesn’t know where to direct it, will direct it to the gateway.

2- Traffic for the network (subnet) 10.0.0.0 with a netmask of 255.255.255.224 (/27) will be directed to the interface S01, which is the interface connected to that subnet.

3- Traffic for the network 10.0.0.32 with a netmask of 255.255.255.224 will be directed to the interface S02, which is the interface connected to that subnet.

LAN Routing and NAT with Windows Server 2016 - IP Routing Table

 

Testing the LAN Routing and NAT

NOTE: for all to work properly, ideally you should have a DHCP assigning IP addresses on each subnet and also a DNS server for your client computers to be able to resolve names and browse the internet.

Having said that, from one of the computer clients connected to S01, you should be able to ping S02. This is the IP config I have at one of my servers in S01. You’ll see that the gateway for this subnet is the IP of the router (10.0.0.30).

LAN Routing and NAT with Windows Server 2016 - IP Config S01

If you ping an IP address in the S02 subnet, this should be the result:

LAN Routing and NAT with Windows Server 2016 - Testing

 

And if you try and browse the internet, voilá!

LAN Routing and NAT with Windows Server 2016 - Testing Internet Browsing

 

And the sames goes from a computer on subnet S02:

LAN Routing and NAT with Windows Server 2016 - Testing S02

 

If you run into any issues, ie, not pinging from one subnet to the other, disable the router firewall and try again. That should do it. Or, instead of disabling the firewall completely, add – or enable – rules to allow traffic between both subnets. In my case, I disabled the firewall completely because this is a lab environment, with no direct connection to the internet.

 

As always, if you found this article useful, share it with your friends.

If you have any questions or suggestions, please leave your comment.

And… Thank you for reading!

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