Date: 24-08-08 12:31
You are using terminology which I've not heard of before. That does not mean it is not correct.
I think what you mean is:
You want to use one server as a gateway. It will have one of the IP addresses from your ISP.
By clients, you mean machines behind the gateway.
Yes, FreeBSD can act as a router like this.
The question is: Why?
What types of services will you be supplying from these machines that require such a setup?