While I ponder why THAT's going on, I thought I'd follow up on your
bpftransmit suggestion. Unfortunately, documentation on Berkeley
Packet Filters isn't very widespread... so I'm having trouble
constructing a simple series of lines of code that will build a
broadcast UDP packet and put it onto the ethernet card. Could you
by any chance point me at a sample I might adapt?
There's a good example of using bpftransmit in the Darwin "bootp"
project. That's where I cribbed mine from.