From NAS-Central Buffalo - The Linkstation Wiki

Attention: What ever you do, you do it on your own risk

Prerequisite

You have to have firmware 1.34 already installed and opened for telnet access. If not, you can find a guide here: Open Stock Firmware LS-XHL

You need to have the optware IPKG system installed on your device. If not, you can find a guide here: Ipkg_on_the_Linkstation_(for_end-users)

For enabling the Microsoft MPPE-Encryption we need a kernel-Module that can be loaded by the stock kernel. For this you need to download the following package:

 http://downloads.buffalo.nas-central.org/Users/kenatonline/nobody/nobody.tgz

For Firmwares before 1.34 this also may work, but it's unknown if the needed Kernel-Modules are also available.

What's the aim ?

The aim is to realize a PPTP VPN-Server

What is needed ?

The good news are: if you have downloaded the package above, and if you are running Firmware 1.34

The bad news: The packages are configured to be used for a service called PocketU (only in Japan). As a matter of fact all boxes outside of Japan are not using those things at all.

As a general guidline for an IPSec-L2TP Server we need: IPSec - Package (here OpenSwan with pluto), an IPSec-Configuration and a tunnel-configuration L2TP - Package (here xl2tp), and xl2tp-Configuration and ppp.xl2tp options