ACraftyMarmoset

So me and two friends have been trying to set up a multiplayer game, but to no avail, sadly :/ Regardless of the host, we get the error "Lost Connection to server. Reason: Unknown Reason" Ideally, I would be the host, I'm running Ubuntu 11.04 Natty Narwhal, and have used the firewall settings gui to open UDP port 20595, but we get the error regardless. Port forwarding is likely to be the issue but I am unable to get that to work, so is it at all possible to use LogMeIn Hamachi to create a VPN and not require port forwards? If not, can someone help me with that? Thanks in advance