[plug] PoPToP PPTP server for Linux ->Windows VPN

[Craig Ringer]

> Just install the debian pptpd package and configure.
> 
> You can't use encryption though unless you apply some kernel patches and
> possibly some patches to ppp.

Hmm.... unencrypted VPNs are not my idea of fun (especially given that 
there will be unencrypted protocols travelling over said VPN). I'll have 
to look into how hard it is to get going in encrypted mode, though from 
what I've read since posting initially it may be an idea to steer well 
clear of pptp for security reasons anyway.

Craig