What is a VPN (Dial-up) client's source address going to be?

[check6]

At this point I am assuming that the source address of the VPN client would be whatever they have assigned on their pc. What I need is a way to know this address.

So, Is there a way to assign a pool of addresses to the dial-up VPN clients? There are various terms for this but Netscreen calls it a DIP (Dynamic IP Pool). But, the idea is that the client's source address gets "changed" to to one of these pool addresses as it passes through the VPN.

Thanks....

[larsdennert]

A dial up client would get an ip from the ISP. That ip is assigned to the client's dialup adaptor. To find out what that "random" ip is run winipcfg or ipconfig on the client after connecting. It changes every time the client dials up.