I have a bridge interface `br0` which usually contains jut `eth0` but
occasionally also needs to contain `usb0`, which is an ethernet-dongle
kind of thing.
How do I setup /etc/network/interfaces for that?
Currently, I just setup everything "manually": `br0` is setup `static`,
and `usb0` is setup as `manual` with post-up scripts that add it to
the bridge.
Is there something better? Like a predefined way to just say that when
`usb0` appears, it should be added to `br0` (and ideally, this would
also `ifup` the `br0` interface if it's not up yet).
Stefan
