see:
http://www.emanuelis.eu/2010/09/15/mknod-lib-udev-devices-ppp-operation-not-permitted-when-updating-ubuntu-10-04-on-virtual-lxc-machine/
see:
http:// www.emanuelis. eu/2010/ 09/15/mknod- lib-udev- devices- ppp-operation- not-permitted- when-updating- ubuntu- 10-04-on- virtual- lxc-machine/