I have 2 NIC on my BM38SP5 box

Internal has 1 IP
External has 2 IP (primary and secondary)

I am using dynamic NAT.

Now dinamic NAT and proxy use one IP address together - primary.

I want make dynamic NAT use one external IP (primary) and proxy use another
external IP - seconadary (some billing reasons)

How can I do that thing?

WBR, Viktor