Sharing internet between wireless iBook and iMac/PC via network cable

Hello all!
Hope you can provide me with help on this: A few months ago, I was able to connect my PC and/or my iMac to my iBook via network cable and jump onto the internet from my laptop's Airport connection. I do not recall making any changes to my computer to do that, it just did. Now it doesn't work (I can get on internet with laptop via Airport, but not from PC/iMac hardwired to laptop). Any ideas?

On the system that has both a wired and wireless connection go to System Preferences -> Sharing , check Internet Sharing and select Share your connection from: <interface connected to Internet> To computers using: and check the interface (Ethernet or Airport) that the other computers are connected to.

Note that this configuration can give you problems when you move laptops to places like Internet Hotspots as the connection will almost kind of work if it's "backwards". I'd recommend using it only on a desktop machine, but if you do use it on a laptop remember to turn it off (just uncheck Internet Sharing) when you leave home. A better solution is to use a dedicated router.

On the system that has both a wired and wireless connection go to System Preferences -> Sharing , check Internet Sharing and select Share your connection from: <interface connected to Internet> To computers using: and check the interface (Ethernet or Airport) that the other computers are connected to.

Note that this configuration can give you problems when you move laptops to places like Internet Hotspots as the connection will almost kind of work if it's "backwards". I'd recommend using it only on a desktop machine, but if you do use it on a laptop remember to turn it off (just uncheck Internet Sharing) when you leave home. A better solution is to use a dedicated router.

Hi, thanks for the suggestion. I did try it before I posted, knowing a little about how it "should" work. I have an unconventional setup perhaps in that the modem and wireless router are upstairs out of reach of any network cable, so I was trying to share the Airport connection on my laptop by connecting the two units with network cable to ethernet ports. It worked fine a few months ago, then something happened.

It should work as described. On the computer with the wireless connection to the router set your Internet Sharing to share the connection FROM AirPort TO Ethernet, then connect the Ethernet cable from that computer's Ethernet port to the non-wireless computer's Ethernet port. Should work. Several things have changed with sharing and the firewall in recent OSX updates, and it is quite likely that defaults have changed enough to make the process a bit more difficult.