L2TP/IPSec VPN Server autoconfig script

Only tested with Ubuntu 12.04 on Amazon EC2 t1.micro

How to Use

1. Set user & passwd in vpn.cfg
2. Run ./start-vpn.sh as root(need only once, will auto started next boot).
3. Connect to vpn server use Win/MAC/IOS buildin vpn client. howto
4. Happy surfing.

What have been done

1. install openswan/xl2tpd from ubuntu official repo.
2. do some dirty work(tune kernel network config, change iptables rules, etc)
3. start L2TP/IPSec service use the user&passwd in vpn.cfg.