Sophos XG: Configuring IP Helpers

IP helpers, also known as DHCP relay agents, are essential for facilitating the distribution of IP addresses and DHCP messages across different subnets. By configuring IP helpers on a Sophos XG Firewall, you can efficiently relay DHCP requests from remote subnets to a centralized DHCP server, ensuring that devices on those subnets receive proper IP configurations and network services.

This comprehensive tutorial will guide you through the process of configuring IP helpers on a Sophos XG Firewall. By following these steps, you can establish smooth communication between DHCP clients and the DHCP server, even in multi-subnet environments.

Step 1: Access the Management Interface

Begin by accessing the Sophos XG Firewall’s web-based management interface:

1. Open a web browser on a computer connected to the same network as the Sophos XG Firewall.
2. Enter the IP address assigned to the LAN (Internal) interface of the Sophos XG Firewall in the browser’s address bar and press “Enter.”
3. Enter the administrative username and password to log in to the management interface.

Step 2: Navigate to IP Helper Settings

In the management interface, navigate to the IP helper settings to configure IP helpers:

1. Click on “Networking” in the top menu.
2. Select “Routing” from the drop-down menu and click on “IP Helper.”

Step 3: Add a New IP Helper

Create a new IP helper entry to relay DHCP requests to the DHCP server:

1. Click “Add” to create a new IP helper.
2. Enter a descriptive name for the IP helper (e.g., DHCP-Relay).
3. Specify the interface from which the DHCP requests will be relayed (usually the interface connected to the remote subnet).
4. Enter the IP address of the DHCP server to which the DHCP requests will be forwarded.

Step 4: Save and Apply IP Helper

Review the IP helper settings and save the changes:

1. Click “Save” to create the IP helper.
2. Apply the changes to activate the IP helper on the Sophos XG Firewall.

Step 5: Verify IP Helper Functionality

To ensure the IP helper is working correctly:

1. On a device located on the remote subnet without a configured IP address, initiate a DHCP request.
2. Monitor the DHCP server to confirm that it receives the DHCP request from the remote subnet via the IP helper.
3. Verify that the DHCP server responds to the DHCP request and assigns the appropriate IP configuration to the device.

Step 6: Additional Considerations

When configuring IP helpers, keep the following points in mind:

1. Ensure that the DHCP server is reachable from the interface specified in the IP helper settings.
2. Multiple IP helper entries may be required if DHCP servers are located on different subnets.
3. Review firewall rules and routing settings to permit DHCP traffic between subnets.
4. Monitor DHCP server logs and IP helper statistics for troubleshooting, if necessary.

Conclusion:

Configuring IP helpers on a Sophos XG Firewall is essential for enabling DHCP relay and seamless communication between DHCP clients and the DHCP server across multiple subnets. By following this comprehensive tutorial, you have successfully configured IP helpers to relay DHCP requests, ensuring proper IP address allocation and network services for devices on remote subnets. With IP helpers in place, your organization can maintain efficient DHCP operations in complex network environments.