I know there are many tutorials on the net for setting up VPN client and server.

I you find one that is simple/short please put a link, I am interested only in the server part.

For client, I will use OS X so I prefer a solution that uses L2TP over IPsec or PPTP because I suppose Cisco IPsec would cost something.

I don't want to spent too many hours setting it up. You know, maybe someone already made a setup script

Note: I am using an EC2 micro instance running Ubuntu 12.04 on it.