OpenVPN setup - server on Ubuntu & Tunnelblick on OS X (Snow Leopard)

README

# install openvpn
sudo apt-get install -y openvpn

# NAT 192.168.99.1/2 subnet <-> eth0 (interface on server)
sudo modprobe iptable_nat
echo 1 | sudo tee /proc/sys/net/ipv4/ip_forward
sudo iptables -t nat -A POSTROUTING -s 192.168.99.1/2 -o eth0 -j MASQUERADE

# generate secret key; scp this key to the client later
sudo openvpn --genkey --secret ovpn.key

# add server config (see openvpn.conf gist)

# start/stop openvpn server
sudo /etc/init.d/openvpn { start | stop | restart }

openvpn.conf

# 
# OpenVPN server config (tested on Ubuntu)
#

port 8080
proto tcp-server
dev tun1

# 192.168.99.1 is the local ip; 192.168.99.2 is the remote IP
ifconfig 192.168.99.1 192.168.99.2

# logging
status /var/log/openvpn.log
verb 3

secret /etc/openvpn/ovpn.key

tunnelblick.conf

#
# Tunnelblick 3.0.0 OpenVPN client-side config; place this under ~/Library/Application Support/Tunnelblick/Configurations
#

dev tun1
proto tcp-client
remote <your-vpn-server> 8080

resolv-retry infinite
nobind
persist-key
persist-tun

# scp the key file from server & put it in ~/Library/Application Support/Tunnelblick/Configurations
secret yourkeyfile.key

# verbose level
verb 3

# upon successful connection, automatically add a default route to route all traffic to the tun
# upon termination of vpn connection, restore the original default route
redirect-gateway def1

# 192.168.99.2 is the local address; 192.168.99.1 is the remote address.
ifconfig 192.168.99.2 192.168.99.1