VPN

[Office]

I have an office with a set of computers that I would like to connect to the HQ, but I'm having some issues that I don't know how to handle.

Office:
5 clients (192.168.0.X) <-> (192.168.0.1) Windows 2003 (Dynamic WAN IP) <-> Internet

HQ:
10 clients (192.168.0.x) <-> (192.168.0.1) m0n0wall  (Dynamic WAN IP) <-> Internet

For the sake of simplicity, both networks have the same layout and same IP ranges etc, which I now realize might be a problem. I kind of need the Windows 2003 server as it acts as a Printer server along with some other Windows related stuff.

As of now, some client IPs overlap, but I guess I could reassign some DHCP ranges to fix it, if that is enough.

Would this work?
- m0n0wall (LAN side): 192.168.0.1
- Windows 2003 (LAN side): 192.168.0.2
- Some general fixed machines: 192.168.0.3-8
- HQ DHCP range: 192.168.0.10-99
- Office DHCP range: 192.168.0.100-199
- Client PPTP connections: 192.168.0.200-216

Can I set the PPTP server (m0n0wall) address to 192.168.0.9 for example?

What I try to accomplish is a seamless connection between the clients at the Office bransch and the HQ, will this work?

It isn't a matter of "overlap" within networks, the two LANs must be in entirely different networks. Change one of them.

ok, I see

So how would the routing between the different LANs be solved?

For example, if client 192.168.1.X want to connect to 192.168.0.Y,
is this solved automatically with PPTP?

Is all traffic routed through the PPTP server, or can I configure each office gateway to
only direct LAN client traffic through the PPTP?

Your best option would be to have an additional Monowall on the Office location and then configure an IPSEC VPN tunnel between the two Monowalls.  This can provide a transparent network connection between the sites.  As already mentioned you will have to change the subnet on one of the sites for the routing to be correct.