I have the following network setup:
LAN====OSX++++Machine A + + ++++++Machine B
OSX is currently sharing an ethernet connection with A and B via an ad-hoc wireless network. This works great, except that Machine A and Machine B can't see each other. They can see the LAN and OSX, and OSX can see both of them. I'm convinced some combination of ipfw and/or natd configuration options can solve this problem, but my networking knowledge is limited enough that I can't seem to Google effectively for a solution. What do I want ipfw/natd to do for me? How do I get them to do it?
(Obviously, I could solve this problem much more easily by the expedient of purchasing a switch, but I feel like I should know how to do this sort of things regardless.)