Passave mode

[Michael Little]

I am 3.0 and am struggling to solve the following problem:

My network was provided with 32 IP addresses from my ISP and the router is
using NAT to map the 16 outside addresses with 16 internal addresses
(external is /27 and Internal is /24 ) I also want to use the Gnatbox
internally but do not want to readdress the network. How can I set the
Gnatbox up in this situation?