Setting up a VPN tunnel between two branch offices takes some effort but it is a grand use of IP protocols to achieve convenience. This project attempts to do that with OpenBSD. You have a clear set of step by step instructions to do this on your own.
Once you download the 7z image, install p7zip and unzip the USB image.
Setting up a VPN involves certain changes to the MODEM/router that connects to the Internet. Usually it is best to just configure the local IP of the VPN node as the DMZ host in the MODEM.
However this is not always possible or desirable. Under such situations you can port forward UDP and TCP 500 and UDP and TCP 4500 to the VPN node. Also forwarding UDP 1194 for OpenVPN is necessary in case you want to setup an SSL VPN. G3VPN support OpenVPN as well.
After the above mentioned steps are done, you have to configure the G3VPN using the web interface as given below.
Please e-mail email@example.com for anything. I can do any amount of customizations for your needs. Support charges are 50$ per site per year.