NM_SERIAL_DEBUG=1 NM_PPP_DEBUG=1 /usr/sbin/NetworkManager --no-daemon
refer:
http://ubuntuforums.org/showthread.php?t=1466490
https://bugs.edge.launchpad.net/ubuntu/+source/network-manager/+bug/259028
http://www.ubuntu-tw.org/modules/newbb/viewtopic.php?viewmode=thread&topic_id=8730&forum=3&post_id=110840
http://www.facebook.com/note.php?note_id=104520692922518
