How to use your Mac as a wifi bridge for your Xbox 360.

… instead of paying $100 for Microsoft’s USB adapter.

In this post you will learn how to use your Mac as a wifi bridge for your Xbox 360. You might consider doing this if your router is not in the same location as your Xbox 360.

What you will need:

• Your Mac.
• Your Xbox 360.
• A crossover Ethernet cable.

1. Open the Network Preferences pane from the System Preferences main window.
2. Ensure that Airport is above Ethernet in the list of network connections on the left. If it is not, click the gear (or settings) icon beneath the network connections box and select ‘Set Service Order.’ Click on Airport and drag it above Ethernet. Click OK.
3. Select the Ethernet connection from the left. From the drop down box labeled ‘Configure,’ select ‘Manually.’
   In IP Address: type ’10.10.10.2′
   In Subnet Mask: type ’255.255.255.0′
   Skip the box labeled Router for the time being.
   In DNS Server: type 208.67.222.222 (which is the openDNS nameserver, in case you were wondering).
   Leave the Search Domain box blank.
   Leave the window open.
4. Open a Terminal window. Terminal is located in ~/Applications/Utilities/, or you could simply do a Spotlight (CMD + Space) search for it.
   In the Terminal command line type ‘ifconfig eth0′.
   After typing that command the second line returned should start with the word ‘inet’ immediately followed by an IP address. Write that address down. Close the terminal window.
5. Return to the Network preference pane, in system preferences. 
   In Router type the ‘inet’ IP address you just copied down from the terminal window.
   Click Apply.
   Click Airport from the network connections pane at the left.
   Find the IP address for your Mac on this connection under Status. Write it down.
   Click Show All at the top of the window.
6. Click on the Sharing preference pane.
   In the left hand pane find ‘Internet Sharing’ and make sure it is UNCHECKED.
   With Internet Sharing unchecked, find the ‘Share internet connection from:’ dropdown box and select ‘Airport.’
   In the ‘To computers using:’ box select ‘Ethernet.’
   Now go back to the left-hand pane and CHECK the box marked ‘Internet Sharing.’
   Quite System Preferences.
7. On the Xbox 360 start at ‘My Xbox’ blade and find settings all the way to the right.
   Select ‘Network Settings.’
   Select ‘Configure Network.’
   Select ‘IP Settings.’
   Select ‘Manual.’
   In ‘IP Address’ type ’10.10.10.3.’
   In ‘Subnet Mask’ type ’255.255.255.0′
   In ‘Gateway’ type ’10.10.10.2′
   Select Done.
   Select ‘DNS Settings.’
   In ‘Primary DNS Server’ type the IP address of your mac. This is the address you were instructed to write down from the Airport section of the Network preference pane.
   In ‘Secondary DNS Server’ type the ‘inet’ IP address from the Terminal session on your Mac.
   Plug the crossover Ethernet cable into both your Mac and your Xbox 360.
   Select Done.
8. Select ‘Test Xbox Live Connection.’
   All the tests should pass with the exception of one NAT warning on the Xbox Live Connection portion. You will be able to play games online and take advantage of Xbox Live with the warning, but this can be resolved by forwarding ports:
   TCP 80
   UDP 88
   UDP 3074
   TCP 3074
   UDP 53
   TCP 53
   one way or the other to the Mac acting as the bridge, from your router. This is different for each model of router and beyond the scope of this article.
9. You just saved $100!