IP Masquerading and Raptor Mobile Tunnel, how to?

I have installed Mandracke 6.5 as a server/router for a small home network.
It is a dual-homed with one nic connected to the cable modem and the other to the hub. I am using class C private ips for the machines on my local network and I have assigned the static ip given to me when I had first installed the cable service.

The server works well and I have used ipchains to get the internal machines to talk to the internet. So far, nothing fancy.

Here is my problem: the original machine that was connected to the internet before I setup the server has RaptorMobile on it. I use RaptorMobile to tunnel through the corporate firewall. This machine has not yet joined my home network. I need to know how to configure it so that the RaptorMobile could still tunnel through.

Is this possible if I assign a private IP to the machine or will the tunneling fail?

If not, do I have to get an IP address to ALL the machines on the internal network or only for the server and the machine with RaptorMobile on it?

Also, in case I get an ip address for the server and for the machine with RaptorMobile installed, do I have to assign a valid IP to the nic on the server connecting the server to the internal network so that the path from the machine with RaptorMobile to the internet has only valid IPs?

As you can see, I am groping in the dark and any help and/or pointers is greatly appreciated.
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Current Raptor mobile VPN clients do not support network address translation...i.e. the machine with the client has to be the one connected to the internet...Tunneling fails for Raptor for everything except the machine the client is installed on... After months of frustration attempting to come up with a suitable solution for clients behind firewalls or DSL routers, we finally scrapped Raptor and went with Compatible systems for this very reason...
naji012600Author Commented:
Thanks for the clarification. What if I assign a network ip address to my machine such that I have the following setup:

Machine A: real ip address
        RaptorMobile installed

Server  Nic1:
        Nic2: real ip address

Linux is routing between Nic1 and Nic2.

Routers are no problem for RaptorMobile, but what about that private ip address on the path? Would that be something RaptorMobile would choke on?

Raptor chokes on the fact that when Linux masqurades an address it put its own address into the IP header...The tunnel is authenticated to the ip address on the machine with the client on it...So the addresses don't match...And vice-versa for NAT...If the tunnel is completed then the ip address behind the firewall is unknown to the Raptor firewall and packets can't be routed back....
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naji012600Author Commented:
My understanding of masquerading is that it is necessary only when a machine does not have a real IP address, is it not so?

From what I have been able to see, Linux performs two seperate yet related tasks: routing and masquerading. The second is not needed for valid IP addresses? Is this correct?

True...Linux can act as a gateway only but I wouldn't do it open access...Masquerading is for firewall type functions...Where all traffic on your internal net looks to the world like it came from the firewall server...The server then keeps track of the internal addresses and translates back to the correct machines...Masquerading is exactly what it sounds like ... The firewall pretends it is your machine...

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