If you're doing your Eclipse / Dragonfly BUG app work on a Mac, you will likely be using the USB ethernet connection to your BUG. Whenever the BUG boots, the g_ether module, which provides the USB ethernet, will by default generate a random MAC. OS X tracks network connections by MAC, and so every time you boot your BUG you will need to go through the process of creating a new enX connection for it, and pretty soon you will have a ton of those lying around.
To avoid this problem, you can make it use a fixed MAC by getting modprobe to pass some parameters to it. To do this, connect to your BUG (either via the serial console with a handylink cable, or via the USB ethernet connection - but be careful if this is your only means of getting to your BUG!).
echo "options g_ether host_addr=46:0d:9e:67:69:eb dev_addr=b6:c8:ab:ac:44:7f" >/etc/modprobe.d/options
shutdown -r now
When your BUG comes back up it should be using a fixed MAC for its USB ethernet connection and your Mac should be a lot happier for it.
If you have a lot of enX connections from starting your BUG that you'd like to get rid of you can edit (again, carefully) the file /Library/Preferences/SystemConfiguration/NetworkInterfaces.plist on your Mac and remove the stale entries. Renumber your new fixed-MAC one to the next highest enX number after your builtin in wired and wireless connections; you'll need to reboot for them to go away. Be sure not to delete your 'real' entries, including ones you may not expect, like the firewire one.