I know this is an old thread but I'm trying to keep all the information about this topic in one place. I set up everything as instructed in this post (I have a macbook wirelessly connected to a local network with an ethernet cable going to the mac pro). Yet when I do this, I get no connection on the mac pro and then the internet connection on the macbook is cut off. When I unplug the ethernet cable from the macbook, the connection is up again. This is a pain. Any good ideas out there?
I know this is a very old threat but in case anyone need the info. It does work to use mbp as your router for the mp.
1) The key is you need an ethernet crossover cable. The regular ethernet cable doesn't work as I just tried it.
2) Once your mbp is set as described above
(A. system preferences
B. sharing
C. internet sharing
D. airport to ethernet)
3) on the mp: follow step A thru C. On step D do: Share your connection from Ethernet 1 / To computers using: Ethernet 2 (checked) If this doesn't work then reverse the order from Ethernet 2 to Ethernet 1.
A dialogue box might come up warning you that this might interrupt your network and internet service provider might cut off service because this might infringe contract rights or what have you.....when that comes up just hit ok
4) Start
Step 4 might come up before step 3 not sure.
Anyways, these are the steps i took and it worked.