Can i extract from XFF the System IP along with Proxy IP

Hi,

I am writing a iRule in which i am able to extract the XFF IP i.e. the proxy IP.

Along with the following XFF IP i even want to extract the System IP from the which the request is generated.

Let's Suppose:

Proxy IP: 163.x.x.x

System IP: 10.56.x.x

Is it possible to extract System IP along with XFF IP.