==== Installation on Ubuntu Server ====
<code>
apt-get install openvpn
</code>

==== Installation on Debian Server ====
<code>
tee /etc/apt/sources.list.d/backports.list << EOF
deb http://ftp.us.debian.org/debian wheezy-backports main
EOF
apt-get update; apt-get -t wheezy-backports install openvpn -y
</code>

==== CA Configuration ====
<code>
cp -r /usr/share/doc/openvpn/examples/easy-rsa/ /etc/openvpn/
cd /etc/openvpn/easy-rsa/2.0
source vars
./clean-all
./build-ca
./build-dh
</code>

==== Server Configuration ====
On CA:
<code>
cd /etc/openvpn/easy-rsa/2.0
source vars
./build-key-server <servername>
</code>
Then copy these files to the target server:
<code>
/etc/openvpn/easy-rsa/2.0/keys/ca.crt
/etc/openvpn/easy-rsa/2.0/keys/servername.crt
/etc/openvpn/easy-rsa/2.0/keys/servername.key
/etc/openvpn/easy-rsa/2.0/keys/dh1024.pem 
</code>

==== Server Configuration File Example ====
<code>
local <ServerIP> # Optional
port 8080
proto udp
dev tun
ca /etc/openvpn/ca.crt
cert /etc/openvpn/server.crt
key /etc/openvpn/server.key
dh /etc/openvpn/dh1024.pem 
ifconfig-pool-persist ipp.txt
server 10.168.1.0 255.255.255.0
push "redirect-gateway"
push "dhcp-option DNS 8.8.8.8"
push "dhcp-option DNS 8.8.4.4"
client-to-client
keepalive 20 60
comp-lzo
max-clients 50
persist-key
persist-tun
status openvpn-status.log
log-append openvpn.log
verb 3
mute 20
</code>

==== Server Restart ====
<code>
service openvpn restart
</code>

Note: Set up [[NAT]] correctly before trying it :D

References: 

  * http://www.vpser.net/build/linode-install-openvpn.html