Internet Sharing not working with my BeagleBone Black
I'm on Debian Wheezy too and this worked for me:


Install Mac drivers from http://beagleboard.org/Getting%20Started
Connect BBB to Mac through USB
On the Mac, go to System Preferences > Sharing > Internet Sharing > Beaglebone Black
In System Preferences > Network, make sure BBB is in the left hand side and shows “Connected”
After SSH’ing into the BBB, run “dhclient” (or "dhclient usb0” if that doesn’t work) and then try “ping google.com”.