18.5. Switching Locations If you travel with a laptop, you know the drill. You're constantly opening up System Preferences Network so that you can switch between Internet settings: Ethernet at the office, Wi-Fi at home. Or maybe you simply visit the branch office from time to time, and you're getting tired of having to change the local access number for your ISP each time you leave home (and return home again). The simple solution is the Location submenu, which appears once you have set up more than one Location. As Figure 18-7 illustrates, all you have to do istell it where you are. Mac OS X handles the details of switching Internet connections. Figure 18-7. The Location feature lets you switch from one "location" to another just by choosing its name— either from the menu (top) or from this pop-up menu in System Preferences (bottom). The Automatic location just means "the standard, default one you originally set up." (Don't be fooled: Despite its name, Automatic isn't the only location that offers multihoming, described earlier in this chapter.) 18.5.1. Creating a New Location To create a Location, which is nothing more than a set of memorized settings, open System Preferences, click Network, and then choose Edit Locations from the Location pop-up menu. Continue as shown in Figure 18-8 . Tip: You can use the commands in the menu to rename or duplicate a Location. When you click Done, you return to the Network panel. Take this opportunity to set up the kind of Internet connection you use at the corresponding location, just as described on the first pages of this chapter. If you travel regularly, you can build a list of Locations, each of which "knows" the way you like to get online in each city you visit. A key part of making a new Location is putting the various Internet connection types (Ethernet, AirPort, Modem, Bluetooth) into the correct order. Your connections will be slightly quicker if you give the modem priority in your Hotel setup, the AirPort connection priority in your Starbucks setup, and so on. Figure 18-8. When you choose Edit Locations, this list of existing Locations appears; click the + button. A new entry appears at the bottom of the list. Type a name for your new location, such as Chicago Office or Dining Room Floor. You can even turn off some connections entirely. For example, if you use nothing but a cable modem when you're at home, you may want to create a location in which only the Ethernet connection is active. Use the Make Service Inactive command in the pop-up menu. Conversely, if your laptop uses nothing but Wi-Fi when you're on the road, your Location could include nothing but the AirPort connection. You'll save a few seconds each time you try to go online, because your Mac won't bother hunting for an Internet connection that doesn't exist. 18.5.2. Making the Switch Once you've set up your various locations, you can switch among them using either the Location pop-up menu (in System Preferences Network) or the Location submenu, as shown in Figure 18-7 . As soon as you do so, your Mac is automatically set to get online the way you like. Tip: If you have a laptop, create a connection called Offline. From the Show pop-up menu, choose Network Port Configurations; make all the connection methods in the list inactive. When you're finished, you've got yourself a laptop that will never attempt to go online. You've got yourself the laptop equivalent of Airplane Mode on a cellphone. 18.5.3. Internet Sharing If you have cable modem or DSL service, you're a very lucky individual. Not only do you benefit from great speed when surfing the Web or processing email, but your connection is on full-time. You never have to wait for some modem to dial (screeching all the way), and wait again for it to disconnect. Too bad only one computer in your household or office can enjoy these luxuries. Actually, it doesn't have to be that way. You can spread the joy of high-speed Internet to every Mac (and PC) on your network in either of two ways: • Buy a router. A router is a little box, costing about $50, that connects directly to the cable modem or DSL box. In most cases, it has multiple Internet jacks so you can plug in several Macs, PCs, and/or wireless base stations. As a bonus, a router provides excellent security, serving as a firewall to keep out unsolicited visits from hackers on the Internet. (If you use a router, turn off Mac OS X's own firewall in System Preferences Security.) • Use Internet Sharing. Mac OS X's Internet Sharing feature is the software version of a router, in that it distributes a single Internet signal to every computer on the network. But unlike a router, it's free. You just fire it up on the one Mac that's connected directly to the Internet—the gateway computer. But there's a downside: If the gateway Mac is turned off or asleep, the other machines can't get online. Most people use Internet Sharing to share a broadband connection like a cable modem or DSL. But in fact, Internet Sharing works if the gateway Mac connects to the Internet via dial-up modem or even a Bluetooth cellphone. The only requirement is that the gateway Mac also has a network connection (Ethernet, AirPort, or FireWire) to the Macs that will share the connection. 18.5.4. Turning On Internet Sharing To turn on Internet Sharing on the gateway Mac, open the Sharing panel of System Preferences. Turn on Internet Sharing, as shown in Figure 18-9 , and then confirm your decision by clicking Start. (In most setups, you'll want to turn on Internet Sharing only on the gateway Mac.) To set up sharing, you have to specify (a) how the gateway Mac is connected to the Internet, and (b) how it's connected to the other Macs on your office network: • Share your connection from. Using this pop-up menu, identify how this Mac (the gateway machine) connects to the Internet—via Built-in Ethernet, AirPort, or whatever. If you select AirPort, you create the software base station effect described in the next section. • To computers using. Turn on the checkboxes to teach your Mac how the other Macs are connected to it—via what form of networking, in other words. Note: Which checkboxes appear here depend on which kinds of Internet connections are turned on in the Network pane of System Preferences. If the gateway Mac doesn't have AirPort circuitry, for example, or if AirPort is turned off in the current configuration, the AirPort option doesn't appear. Figure 18-9. Ka-ching! Mac OS X's Internet Sharing just saved you the cost of a $50 hardware router. In this example, the Mac is connected to a cable modem via Ethernet. But other Macs are connected to it via wireless AirPort and by a FireWire cable. And now they can get online, too, even though they're not directly connected to the cable modem. Now visit each of the other Macs on the same network. Open the Network pane of System Preferences. Select AirPort, Built-in Ethernet, or FireWire—whichever reflects how each Mac is connected to your network. Then, from the Configure pop-up menu, choose Using DHCP. Leave everything else blank. Finally, click Apply Now. As long as the gateway Mac remains turned on, you should find that both it and your other Macs can get onto the Internet simultaneously, all at high speed. (Even Windows PCs on the same network can also get online, as long as you set them up to use DHCP just as you did your "downstream" Macs.) Note: If you're like most people, your gateway Mac has only one Ethernet port. How, you may wonder, can you plug in both the cable modem and the local network?One approach is to install a second Ethernet card. The more economical approach: Connect the cable modem to the Uplink or WAN jack on your Ethernet hub or router. (On some models, an ordinary Ethernet port can be turned into an Uplink port if you flip a tiny switch.) Your gateway Mac plugs into the hub as usual. 18.5.5. The Software Base Station Effect If the gateway Mac has AirPort circuitry, turning on Internet Sharing (and "To computers using: AirPort") has another profound effect: It creates a software base station. The Mac itself is now the transmitter for Internet signals to and from any other AirPort-equipped Macs within range. You just saved yourself the cost of an Apple base station. Tip: Internet Sharing can create the opposite effect, too: Instead of letting a wireless Mac piggyback on a wired Mac's connection, you can let a wired Mac share a wireless connection.Suppose, for example, that you and a buddy both have laptops in a hotel lobby. You're online, having paid $13 to use the hotel's Wi-Fi network. If you set up Internet Sharing appropriately, your buddy can connect to yours via an Ethernet cable or even a FireWire cable and surf along with you—no extra charge. . 18. 5. Switching Locations If you travel with a laptop, you know the drill. You're. Figure 18- 7 illustrates, all you have to do istell it where you are. Mac OS X handles the details of switching Internet connections. Figure 18- 7. The