ACCEL-PPTPD Server
After trying to find a newer version of PPTP Server with Kernel Driver support I started to change POPTOP PPTP Server version 1.4.0 and add Kernel Driver support ported from accel-pptp 1.3.3. For more information check here http://accel-pptp.sourceforge.net/ The idea is pretty simple: create a socket AF_PPPOX of type PX_PROTO_PPTP. Then lunch PPP with plugin pptp.so which will configure the pptp kernel driver with endpoints and then everything is encapsulated/dencapsulated via kernel driver
I'm using this software because is very easy to integrate radius and other plugins.