Seems I wasn't using a crossover cable, I don't know why anyone would make a yellow cable that wasn't crossover.
Anyway, now I have input via telnet, but I can't get the Mac to boot to a OF telnet session?
I tried to set it via nvramrc, but that doesn't seem to work:
setenv auto-boot? false nvedit " enet:telnet,10.1.2.3" io nvstore setenv use-nvramrc? true reset-all
Returns me to the OF prompt but no in telnet.
I seem to recall doing this on an Old World Mac many years ago, I need to change the input-device and output-device to enet?