Important note about SSL VPN compatibility for 20.0 MR1 with EoL SFOS versions and UTM9 OS. Learn more in the release notes.

Sophos Firewall: DHCP over IP Alias

Disclaimer: This information is provided as-is for the benefit of the Community. Please contact Sophos Professional Services if you require assistance with your specific environment.


This Recommend Read shows you how to configure a DHCP server on an Alias IP

Alias IP

You may refer to the following KB for reference:

Add an alias

Step 1:Creating an Alias on Physical Interface

Go to Network> Interfaces, click Add interface, and then select Alias.

Step 2:Alias IP Configurations

 Specify the following

  • Physical Interface
  • IP version
  • IPv4/Netmask or IPv6/Prefix

DHCP for Alias IP

Go to Network > DHCP > Server > Add.
Create an Alias Network Range.

  • Interface: Alias Interface won't show on the Interface drop-down. Select the Port where Alias is created.
    • Ex. Port1
  • Dynamic IP Lease: “ IP Alias” needs to be input manually.
  • Gateway: “Use interface IP as a gateway” needs to be unchecked
    • Enter the IP address of the Alias IP

See the screenshot below.

To further verify.
Go back to Network > DHCP > Servers.

Network > Interfaces

DHCP Leasing on a workstation

In command prompt

Type ipconfig /release and then Ipconfig /renew

Fixed wrong format
[edited by: Erick Jan at 11:55 PM (GMT -8) on 12 Dec 2023]