I wanted my desktop to have Internet access but since it's not close to my router and I don't want to pay some $70 for a PCI wireless card, I decided to connect the desktop with an Ethernet cable to my MacBook, which is connected via wireless through AirPort.
So, this is what the Mac help says:
1. Open System Preferences, click Sharing, and then click Internet.
2. Choose a network port from the "Share your connection from" pop-up menu.
3. Select "Built-in Ethernet" or AirPort depending on which computers will share your Internet connection.If you have turned on the firewall on the Firewall pane of Sharing preferences, you also need to turn on Personal Web Sharing on the Services pane of Sharing preferences in order to share your Internet connection and allow computers connected to your Internet connection to browse the web.
This need to turn on Personal Web Sharing is confusing since stopping it is to “prevent users of other computers from accessing Web pages in the sites folders on this computerâ€; I'm not sure how this is related to making a bridge for Internet sharing.
So in my case, I selected “Share your connection from: AirPort†to computers using “Built-in Ethernet†and I allowed “Personal Web Sharing†in Services (it automatically allows it in the firewall settings).Now, there's a couple of extra steps to take, at least with my default configuration.
After the previous steps I lost Internet connectivity in the MacBook, and this is because it was trying to connect thru the Ethernet port, ie, Ethernet has higher priority by default than the AirPort wireless port.
This can be checked in System Preferences -> Network and “Show: Network Statusâ€; I see that the Ethernet interface was assigned the private address 10.10.10.1 and at first it was saying “You are connected to the Internet via Ethernetâ€. I changed to the view “Show: Network Port Configuration†and in effect, Built-in Ethernet was higher up in the list than AirPort, so I dragged AirPort to the top of the list and gained the connectivity back.
Now, regarding the computer that is connected to the Ethernet, it's not likely that its network settings will be ready for the connection; many will have DHCP by default and the MacBook is not offering that service (at least by default). So I setup a fixed ip address in the desktop, 10.10.10.2 (or 10.10.10.whatever) with a network mask 255.255.255.0 and as gateway the MacBook: 10.10.10.1.
So everything is working fine now. As an additional note, the MacBook Ethernet port supports both regular network cables and cross-over ones; it will auto-detect the type of cable and it can work in both modes automatically, so you don't need a cross-over cable to connect directly to another computer, you can use a regular patch cable. (I checked that it works with both types of cables).
Too Cool!
