Abstract:

In today’s interconnected world, network security is of utmost importance. One effective technique for securing a network is subnet whitelisting, which allows only trusted IP addresses to access the network. Windows operating systems provide several tools to implement subnet whitelisting, but it can be challenging for network administrators to navigate through the different options available. This article provides a comprehensive guide on how to whitelist a subnet on Windows, including the necessary steps to set up the Windows Firewall and configure the routing tables.

Introduction:

Subnet whitelisting is an essential tool for network administrators who need to secure their network against unauthorized access. By allowing only trusted IP addresses, subnet whitelisting prevents attacks from malicious actors and minimizes the risk of data breaches. Windows operating systems provide several tools to implement subnet whitelisting, but the process can be confusing for network administrators who are not familiar with the technical aspects of network security.

This article will guide network administrators through the process of implementing subnet whitelisting on Windows. We will cover the steps to configure the Windows Firewall, create routing rules, and test the configuration.

Setting up the Windows Firewall:

The Windows Firewall is a built-in feature that allows administrators to control inbound and outbound network traffic. To whitelist a subnet, administrators must first create a new inbound rule that allows traffic from the desired subnet. To do this, follow these steps:

1. Open the Windows Firewall with Advanced Security console by typing wf.msc in the Run dialog box.
2. Click on Inbound Rules on the left-hand side of the console.
3. Click on New Rule on the right-hand side of the console.
4. In the New Inbound Rule Wizard, select Custom as the rule type and click Next.
5. Select All programs and click Next.
6. Select Protocol type as TCP and specify the port number(s) that you want to allow traffic for. Click Next.
7. Select the “These IP addresses” option and add the subnet you want to whitelist. Click Next.
8. Select Allow the connection and click Next.
9. Give the rule a name and description, then click Finish.

Creating Routing Rules:

The next step is to create routing rules to direct incoming traffic to the appropriate destination. This step requires knowledge of the command-line interface (CLI) and the use of the Route command. To create a routing rule, follow these steps:

1. Open the Command Prompt as an administrator.
2. Type the following command: route add <destination network> mask <subnet mask> <gateway IP address> metric 1 if <interface number>
3. Replace the <destination network>, <subnet mask>, <gateway IP address>, and <interface number> with the appropriate values. The <interface number> can be obtained by typing the command “route print” in the Command Prompt.
4. Press Enter to add the routing rule.

Testing the Configuration:

After completing the above steps, it is essential to test the configuration to ensure that it is working correctly. To test the configuration, follow these steps:

1. Connect a device to the subnet that you want to whitelist.
2. Try to access the network resources that you have allowed in the Windows Firewall rule.
3. If you can access the resources, the configuration is working correctly.

Conclusion:

Subnet whitelisting is a vital tool for network administrators who need to secure their networks against unauthorized access. Windows operating systems provide several tools to implement subnet whitelisting, including the Windows Firewall and routing rules. By following the steps outlined in this article, network administrators can configure their Windows systems to whitelist a subnet effectively.