IPCOP is one of my favourite pieces of software. It is a great internet gateway solution for home users and small to medium businesses. I use the Zerina addon to install OpenVPN and this in my option turns IPCOP into the best open source VPN/Firewall/Proxy solutions out there.
Following on from here. Another issue I find is when you install it; it does not push through DNS from the local network (green interface). To solve this problem it is a simple configuration change made to one file.
The easiest way to do this is use WINSCP to connect to your IPCOP machine. Locate the file server.conf from the location below
/var/ipcop/ovpn/server.conf
Edit the file adding the following line, just add it at the bottom.
push “dhcp-option DNS 192.168.0.5″
Replace ‘192.168.0.5‘ with your internal DNS server for the Green network.
Save the file and reboot IPCOP.
Now when your clients connect they can use IP or the DNS name of the computers in the green network!