This week’s tip is intended more for the Mac power user. If you are the type of user who wants to get the most out of your Mac and explore more of its true potential, this tip is for you!

With the release of OS X, the Macintosh has become a powerful server platform. OS X makes it incredibly easy to set up web, mail, and file sharing services. And, with so many resources available, it often becomes necessary to bind several IP addresses to a single computer. For example, I may be running my web site at www.maclive.net and my ftp site at ftp.maclive.net. Generally speaking, each name needs its own corresponding IP address. For my example, www.maclive.net = 10.12.2.119 and ftp.macsales.com = 10.12.2.122. For more information on how DNS names and IP addresses are related, please click here.

Support for Muti-Homing (the binding of multiple addresses to a single network card), was possible from OS 8.6 through 9.x, but support was primitive. With its UNIX underpinnings, OS X has much more to offer. And while many people may have a need to bind multiple addresses to a single computer, there is little documentation detailing how to accomplish it.

Here's How:
Open the Network Preference Pane. The Show menu will list all available network adapters in your computer. There will be one option named Built-in Ethernet, and options for Airport and Internal Modem if your system has these devices installed. At the bottom of the menu is an option called Network Port Configurations. Once there, you will have the ability to deactivate any unnecessary adapters on your system.

Clicking the New button allows us to give the new interface a name as well as choose the hardware it is associated with. For example, I have an OS X server that will be serving a web site with the address www.maclive.net. I want to run an ftp server with an address of ftp.maclive.net. I will name my new interface ftp.maclive.net. Under the Port menu, I choose Built-in Ethernet because I want that traffic to enter and exit my computer through the Built-in Ethernet card. If I had multiple network cards installed, as is the case for users who have Airport installed, these other network adapters are also valid choices.

Once the new adapter is added, it is available in the Show menu. Select your new configuration and you will have the ability to set up the network properties for TCP/IP. Doing this effectively adds an additional IP address to your Mac.

Having the ability to bind multiple IP addresses to your Mac gives you great flexibility when you want to host many web or ftp sites. But if you are creative, you can find other uses for these configurations. A less conventional example would be the ability to use your Mac as a router for every computer in your house.

Many DSL providers only offer customers a DSL modem. If you have a DSL router, you can easily share that single connection with every computer on your LAN. Odds are that your provider gave you a modem in order to limit access to one computer at a time. But, did you know you could connect the DSL modem to your Mac and then set the Mac to act as a router? In this scenario, it is easy to share the Internet connection of that Mac’s modem with the rest of computers on your network.

Next week we will take a look at a relatively easy way share your Mac’s DSL or Cable modem with the rest our your network. You’ll need to be able to multi-home your Mac in order to accomplish this, so a firm understanding of this article will be important.