Windows-UNIX hybrid network over VPN

[Randseed]

My life works well until Windows gets involved in something, then suddenly the simplest things become insanely complicated.

A friend with a small business has some Windows software package that networks itself by using a Windows file share. So if you stick all the Windows machines on a network, they'll talk, no problem. The catch is that they want to do it from off-site over a VPN too.

This means we have something like this:

Site 1: 1 Linux router, with terminals A and B connected to it through a switch.
Site 2: 1 Linux router, with terminals C and D connected to it through a switch.

A VPN connecting the two routers.

Right now, A and B can talk to each other and the Site 1 Router, and that router (running Linux) will route them out to the Internet if they want. The same thing with C, D, and Site 2. Setting up a VPN between the two routers wasn't difficult with OpenVPN, and soon enough they're sitting there pinging away.

The catch is that no matter what I do, I can't seem to get traffic to route from one terminal on one side to another one on the other, like from A to C.

Site 1 Router internal address: 192.168.100.1
Site 1 Router VPN address: 192.168.101.1
Terminal A: 192.168.100.2
Terminal B: 192.168.100.3
Site 2 Router internal address: 192.168.102.1
Site 2 Router VPN address: 192.168.101.2
Terminal C: 192.168.102.2
Terminal D: 192.168.102.3

On site 1 router: route add -net 192.168.102.0/24 gw 192.168.101.2
route add -net 192.168.101.0/24 gw 192.168.101.2 dev tun0
On site 2 the inverse.

Maybe it's caffeine deprivation, because I've set this kind of system up before, but what in God's name and I missing? And yes, both routers have /proc/sys/net/ipv4/ip_forward set to true. Is it the subnetting I did, meaning do the Windows machines just stare at it and go "duh?" The default route for those machines should be to use the router as a gateway regardless.

And then, once all that works, what headaches and I am going to run into trying to mount the Windows XP-hosted file share over the VPN?

Thanks for any help.

[Katphish]

Hi,

What are you using for a firewall? Do you have the rules setup for the subnets?