I see this tutorial, http://djinnsour.com/2015/08/23/adding-a-public-ip-address-to-a-system-behind-pfsense-using-nat-11/. Author of this blog say, add external ip to this network, so what is the public ip ( whatismyip ) of that machine?
Referring to that tutorial, the external IP address (routable) would be the 222.222.222.x range address.
Anything within 192.168.x.x will be a private range which can only be used internally as per RFC1918 hence why you would use NAT.
Hope this helps you on your quest.