Is it possible to configure a Tunnel VPN between 2 Untangle NG Firewall boxes where the tunnel goes through another private network. I have my main network 192.168.1.0/23 with a Untangle NG firewall. I want to create a separate Domain with parts in 2 different buildings which are physically connected with my main network. I know there might be a way to use VLAN's to do this but there are numerous different switches between the two locations and I would like to keep my main network as simple as possible. my initial thinking is the two new Untangles, A and B would each have an internal network of 10.75.75.0/24 with A having a Domain Controller with DNS/DHCP/AD, etc. Untangle A would also have a WAN port providing Internet access to both A and B. Untangle A would have a 3rd port connected to my main network with a static IP of 192.168.0.200. Untangle B would have a WAN port that connects to my main network with a static IP of 192.168.0.201. These locations have less than 10 PC's combined and my main network has 1GB fiber/copper connections so I need to separate them from my Domain, but what them to have the best possible connection for all the PC's in this new Domain.

Thanks for any advise.