iMac Internet Sharing Problems

[kmkl]

So heres the case:

A friend came over to show off their new MB Pro.
They wanted to connect to the internet, but since I don't have a router, I thought I would just share the internet connection through Airport. Having no way to test it before their arrival, I thought nothing about it.

So when they did arrive, we immediately tried connecting the MB Pro to the iMac. In their airport menu-bar menu we could see 'Daniel ********'s iMac'

We click, and it supposedly connects.

A new device called Daniel...iMac appears under Shared in a Finder Window.

When I click the Icon and name, it opens (in the same window) a blank list, and a bar at the top with the iMacs name, and a button for connect as...

We also see the classic spinning black flower thing at the bottom right corner of the window.

We think its connected already and go to open Safari; "could not connect to the internet, blah blah..."

So i play around in Network Preferences and in Sharing preferences, and nothing.

I even try with their new iPod touch, nothing.


But when I hooked up the ethernet cable running from the modem to the iMac into the MB Pro, and set up to share internet, the iPod touch connects :|

Does anybody know what I could do to fix the iMac's problem? I'm looking to buy an iPhone and use wifi from the iMac, but if it doesn't work, poop.

And please don't recommend getting a router, as there is no real point, since this will be the only computer in the house...


Thanks for the help.

Edit: After playing around with Firewall, and setting it to Allow all incoming connections. (before it was Allow only essential services)

Question though: will I be safe if I leave the all incoming connections on? or should I turn it off?

 

[Cave Man]

You iMac must be connected to your internet point (e.g., router) by ethernet cable (or, less likely, firewire), then in the System Preferences' Sharing pane you can share your iMac's internet access through Airport.

You cannot use and share the same port.

 

[kmkl]

You iMac must be connected to your internet point (e.g., router) by ethernet cable (or, less likely, firewire), then in the System Preferences' Sharing pane you can share your iMac's internet access through Airport.

You cannot use and share the same port.

So then why does the MB Pro sharing work right away?
All I did was take the cable out of the iMac and put it into the MB Pro

Also I don't have a router, the ethernet cable is connected to a wireless modem from outside the house. (As I live in a rural area)

 

[Cave Man]

Straight from Leopard's help:

Sharing your Internet connection

If your computer is connected to the Internet, you can share its connection with other computers on your local network.
For example, if your computer is connected to the Internet using a DSL modem and has an AirPort Card installed, you can share the DSL connection with other AirPort-equipped computers.
On Windows computers, sharing your Internet connection is sometimes referred to as a “network bridge” or as “bridging your network.”

To set up Internet sharing:

1. Choose Apple > System Preferences, and then click Sharing.
   
2. Select Internet Sharing.
   
3. Choose a network service from the “Share your connection from” pop-up menu, Ethernet for example.
   
4. Select a networking service to share your Internet connection from the “To computers using” list, AirPort for example.
   
5. If you share your Internet connection using AirPort, click AirPort Options and give your network a name and password.

If your Internet connection and your local network use the same port (Ethernet, for example), investigate possible side effects before you turn on Internet sharing. In some cases (if you use a cable modem, for example) you might unintentionally affect the network settings of other ISP customers, and your ISP might terminate your service to prevent you from disrupting their network.

 

[XClint]

iPhone Access to the iMac Wi-Fi Network, sharing internet...

So this set-up is exactly the same step-by-step procedure for 10.5.X on an iMac 24 to act as a bridge so that the 2G iPhone can share the internet etc?
My router is half way down the house with an ethernet network to other parts of the house, and not strong enough, yet I need to extend my wireless network for the 2G iPhone.
So how do we use the iMac 24 using 10.5.X to act as a wireless bridge, and how secure is this?

Cheers from New Zealand!