IP Networking

i have one private network with one ip address, and i have a seperate network on a seperate ip address.
now, each network is behind a firewall/router. now what i want to do is be able to access one server on the second network from a computer on the first., but with the private ip address, (this is so i can use insecure services on both networks from one computer which can be on either network.) have i lost anyone? ok so what i want to do is this, i want to throw together another computer, i dunno what its gonna run, maybe a single floppy unix varient, so i can run a diskless machine, it will have 2 nic's and will be connected to the router of each network. now i know there can be no duplicate ip address, but i am not sure how to set up the gateway. will i have to change settings in each of the existing routers on the 2 networks? please help!

hmm i re read that and I got lost, maybe this will help:


#internet#
network 1--^ ^---network 2
^------???-------^
those question marks represent "what do i do??"

The easiest solution would be to forget about your machine attached to both firewalls and just configure the firewalls to allow what you want. There are several options, but basically you would configure one or both firewalls to create a tunnel between the two firewalls over the internet. The exact details will depend on your firewall vendor but would go like this:

PC1--FW1=====FW2--PC2

The === would be your tunnel. Depending on your security requirements you may want to make FW2 a VPN endpoint so you can connect from anywhere on the internet to the LAN behind it after you give some credentials. If this is too risky, then you can configure FW1 and FW2 to have a permanent tunnel between the two of them so only PCs belonging to LAN1 or LAN2 can talk to each other and there is no (well maybe a little) chance of anyone not on LAN1 or LAN2 connecting to LAN1 or LAN2 via FW1 or FW2.

Hope this helps. This is basically what you were trying to accomplish with your third PC connected to both Firewalls but there is not need as most firewalls have the functionallity to do this and it is much easier to implement.

thanks! i hadnt really thought of tunnling it, i guess what i could do is just configure the firewall to accept request from my ip addresses only, i guess as long as no one knows that these two networks are related theres no problem with people trying to get in that way, by spoofing my ip address. thats probably what im gonna do seeing as im out of spare computer parts! thanks again.