Bluetooth Linux issue

[Stephen Hemminger]

I had several issues getting Bluetooth to work well on Linux.
There are lots of things that could be fixed to make it more usable, but one
none obvious thing is that the Modem Manager process was opening and camping
on the rfcomm device. This caused subsurface to get -EBUSY.

The workaround was to manually stop the service with:
 $ sudo service ModemManager stop

do this before creating rfcomm.