Looks like you need Nullsana.device, which will route
between the Mac and the
Amiga TCP/IP stack.
At one time I was going to use my A2286 bridgeboard with an
ISA NIC card so that I could use ethernet on my A4000 cheaply. The
performance wasn't a big issue and the drivers and such to 'bridge'
the Amiga TCP/IP to the ethernet port on the ISA board were available
on Aminet. In theory, it should've worked under Shapeshifter as well.
Jeff
--
Collector of Classic Microcomputers and Video Game Systems:
Home of the TRS-80 Model 2000 FAQ File
http://www.geocities.com/siliconvalley/lakes/6757