Sunday, June 21, 2009

Turn your Mac into a wireless access point

I spent the weekend out of town and the hotel where I stayed included high speed Internet in each of the rooms via a supplied Ethernet cable. I had my MacBook Pro and iPod Touch with me. Using some of the features included out-of-the-box on my laptop I was able to turn it into a wireless access point, allowing my to get online with my iPod as well as my laptop. These directions should work for any computer running OS X 10.5 Leopard. If you are still running OS X 10.4 Tiger this functionality is still there but some of the menus have different names. My MacBook Pro is running OS X 10.5.7.

First, make sure the wired network connection is working properly on your Mac. Once you have verified that, open up System Preferences. Click on the Sharing button. This will open the Sharing preference pane. If the lock icon at the bottom left of the window is locked, click on it and enter an administrative password to unlock it.

On the left side of the windows is a list of available services to configure. Some of them may have check marks next to them, indicating that they are turned on, but for you none of them may be on. Click on "Internet Sharing" but don't click the checkbox yet.

Now on the right there is an option that says "Share your connection from:" with a drop down menu to choose the available network interfaces. Since you are most likely sharing from your wired Ethernet connection, like I did, choose "Ethernet". Below that is an option that says "To computers using:" followed by a list of interfaces to share your connection with. Click the checkbox next to AirPort to allow other devices to connect to a wireless network that will be broadcasted from your Mac.

Next click the button at the bottom right that says "AirPort Options...". In the top box you can specify the name of the wireless network you will be broadcasting. Leaving the Channel set to "Automatic" should be fine. Next you will probably want to enable some security. Unfortunately, OS X 10.5 Leopard only supports broadcasting with WEP encryption. WEP was one of the early attempts at wireless security and it is easily broken using tools like Aircrack-ng. Hopefully OS X 10.6 Snow Leopard will support WPA2 which uses AES and has yet to be broken.

Never-the-less, I still would recommend using the WEP encryption because it is better than nothing and will stop most users. Just be aware that someone who knows what he is doing will still be able to get access to your network. Click the checkbox that says "Enable encryption (using WEP)". At the bottom next to "WEP Key Length:", choose "128-bit". New enter a 13 character password. I recommend using upper and lower case letters in addition to numbers and avoid using dictionary words. Click OK to close the options box.

Now you are back at the Sharing preference pane. Since all of your options have been set the way you want, click the checkbox next to "Internet Sharing" on the left. If your AirPort is turned off you will get a pop-up asking if you want to turn on your AirPort card. Click "Turn AirPort On". Next you will get a pop-up asking if you are sure you want to turn on Internet sharing. Click "Start".

Now your laptop is all set for wireless devices to connect to it and share your network connection. When you are finished sharing your network connection you should be sure to turn "Internet Sharing" back off by unchecking the checkbox next to it in the Sharing preference pane.

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