IPSec, Racoon, and roaming clients

[Paul Lathrop]

I have recently been asked to implement VPN access for some of our 
roaming employees. Our gateway is a FreeBSD 4.7 box that I administer. 
Our employees are all on cablemodem connections when they are out and 
about. I have discovered IPSec and racoon, of course, and dug through 
their documentation. I have also read several very good tutorials on 
the web. The trouble I am having is that all the information I can find 
is for setting up a VPN tunnel between two gateways. What I need is a 
VPN connection between a roaming host (with a dynamic IP) and our VPN 
gateway (static IP) which will allow access to the internal network 
behind that gateway (private IP addresses). I have successfully 
established the VPN connection between a roaming host and the gateway, 
but without access to the internal network. I can't seem to figure out 
how to tell setkey to configure a tunnel into the network without 
knowing ahead of time what the client's IP will be.

Can anybody give me some pointers?

Thanks,
Paul D. Lathrop