Passing external IP to internal device without NAT

Question

Hi, 
 
 We are migrating from SonicWall to Sophos XG210. 
 
 We have a linux firewall that protects our phone system. With our current SonicWall config we have an interface setup in "Transparent IP Mode Splice L3 Subnet" which allows us to use one of our external IP addresses 10.2.2.3 for example on the NIC of our Linux firewall and use the upstream gateway as the Linux Firewall NIC gateway. 
 
 How can I replicate this with the XG210? 
 
 Thanks in advance.

Vishal_R · Accepted Answer

Hi JohnSmithers If I am correct you would like to assign the public IP to your LAN or DMZ device behind the firewall. With XG you may achieve this with the help of Proxy ARP based scenario or setup. Please refer below KBA on how to setup Proxy ARP with XG: 
 https://community.sophos.com/kb/en-us/123525 Note: Proxy ARP will not work if there is any other L3 device in between end machine where you have assign public IP and XG.