I am wondering if someone has a recipe to configure IPSEC/LT2P-PSK VPN for the Pi. I am interested in being able to connect to it with an iDevice, and an Android phone.
I dont have a recipe for installing a IPSEC / L2TP VPN; I tried to install it and after a couple of hours gave up in frustration and opted for a PPTP VPN.
PPTP is much easy to manage and install, although please take note its not as secure as IPSEC / L2TP, but it will support connections from iOS and Android devices unlike OpenVPN.
Depending on why you need a VPN, the increased risk associated to using PPTP over IPSEC/L2TP might be acceptable, if it is you will find a recipe for installing PPTP here http://www.stuffaboutcode.com/2012/08/raspberry-pi-use-as-vpn-server.html
I don't know if this exactly is what your looking for but this tut may help you: https://dl.dropbox.com/u/21429092/OpenVpn%20server%20Raspberry%20Pi.pdf
OpenVPN now has Windows/Mac/Android/iOS clients. Here is a pretty good write up on OpenVPN for Raspberry Pi. http://sandeepmore.com/blog/2012/08/21/openvpn-for-raspberrypi-static-key/
A quick and easy write up for PPTP VPN on Raspberry Pi. http://www.sigwo.com/sshvpn-setup-guides-for-raspberry-pi/