Configuring Windows Server 2012 R2 as a Router

Windows Server 2012 R2 routing/NAT functionality feature is a part of Remote Access and allows for connecting 2 networks together, allowing a Windows machine with at least 2 NICs on 2 separate networks to handle the routing between them.
To install this feature complete the steps below.

Prerequisites

• Windows 2012 R2
• 2 Physical or virtual NICs
• Static IP's on each NIC, 1 on each separate network

Setting up Windows Server 2012 R2 routing/NAT functionality

1. To start, from Server Manager click Manage > Add Roles and Features.
2. On the Before You Begin page, click Next.
3. Select Role-based or feature-based installation and click Next.
4. On Server Selection select the server you want to install the feature on and click Next.
5. In the list of Server Roles, select Remote Access and click Next.
6. On the Features page click Next.
7. Click Next on Remote Access.
8. On Role Services click the Routing checkbox. Click Add Features on the pop-up dialogue.
   
   Figure 1: Add Roles and Features Wizard
9. Click Next
10. Click Next on the Web Server Role (IIS) page.
11. On this Role Services page, leave the defaults and click Next
12. Finally on the Confirmation screen click Install
13. The Feature has now been added to Windows. A reboot is not necessary for this process so we will now proceed to the next part of the configuration.
14. From Administrative Tools look for Routing and Remote Access. Open the console and you will see a red down arrow over the server name.
15. Right-Click the server name and click Configure and Enable Routing and Remote Access.
    
    Figure 2: Routing and Remote Access screen
16. The Routing and Remote Access Server Setup Wizard appears.
17. Click Next.
18. On the Configuration screen select Network Address Translation (NAT).
    
    Figure 3: Routing and Remote Access Server Setup Wizard
    NOTE: If desired you may select VPN & NAT if you wish to setup VPN functionality on the system as well.
19. Click Next.
20. Here you will select your network interface that is connected to the external network or internet.
    
    Figure 4: Routing and Remote Access Network Interface selection
21. Click Next.
22. Next you will need to select to have RRAS provide DHCP and DNS forwarding or otherwise select that you will set up DHCP and DNS on your network later, if desired.
23. In our configuration we will choose the second option as under most circumstances you will set up DNS and DHCP separately from RRAS.
    
    Figure 5: Routing and Remote Access NAT Services
24. Click Next.
25. Click Finish.

Windows is now configured as a router with a private network and an external network connected.

Figure 6: Setup complete with Private and External Networks