Section 33. Share Your Internet Connection


33. Share Your Internet Connection

BEFORE YOU BEGIN

27 Set Your Network Device Preference Order

30 Configure Networking Manually


SEE ALSO

42 Create a Computer-to-Computer Network


Suppose that you have only a single dial-up Internet connection but several computers that all have to be online at once. Normally, you can hook up only one computer at a time, through its own modem connection. But thanks to Internet Sharing, all the computers can be online at once, sharing the same connection.

In this arrangement, one Mac is the central server that shares its connection with all the other computers. That Mac must have a working Internet connection such as the internal modem, Ethernet, or any other network port. That central Mac must also be hooked up to the other computers using an infrastructure such as AirPort or Ethernet. For instance, you might have a Mac with an Ethernet connection to a DSL modem, and an AirPort card with which it can share its connection with other AirPort-equipped computers; or your Mac might have a dial-up modem connection and be plugged in using Ethernet to a hub, with all the other computers likewise plugged into the same hub.

33. Share Your Internet Connection


One network port on the central Mac is the active Internet connection, and the other port is the one you use to share the connection. All the other computers on the network need only be configured to use DHCP to obtain their TCP/IP information, and to use the same network device for their Internet connections that you're using to share it. For instance, if you are sharing your connection over AirPort, all the other computers must be using AirPort or compatible 802.11 devices as well.

KEY TERMS

802.11 A protocol for wireless network connections. Apple's implementation is called AirPort; the same technology is also referred to in the rest of the industry as Wi-Fi. 802.11b, the earlier standard version, runs at 11 megabits per second; 802.11g, the more modern version, runs at up to 54 megabits per second and is called AirPort Extreme by Apple. AirPort is an optional add-on for most Macs.

Network Address Translation (NAT) A scheme that allows computers on one side of the router to have different IP addresses in a special rangeusually 192.168.2.0 to 192.168.2.255 and for those computers to all share a single true IP address on the other side of the router.


When your Mac has Internet Sharing enabled, the computer is actually acting as a DHCP server and NAT -enabled router. This means that external computers can't connect directly to any of the computers sharing their Internet connection from your Mac, because all they can see is the single real IP address that all the computers on your network are sharing.

NOTE

Computers sharing their Internet connections from your Mac don't all have to be Macs. Windows and Unix machines can all share your Internet connection; all they have to do is get their TCP/IP information through DHCP and use the network device you're using to share your Mac's Internet connection.


1.
Open Sharing Preferences

Open the System Preferences application and click the Sharing icon to open the Sharing Preferences pane.

2.
Go to the Internet Sharing Settings

Click the Internet tab to open the Internet Sharing configuration panel.

3.
Select an Internet Connection to Share

All your active network ports are shown in the Share your connection from drop-down menu. To share your Internet connection, select the connection you want to share. For instance, if your connection to the outside Internet comes from a dial-up modem, select Internal Modem .

4.
Select a Network Port for Internet Sharing

In step 2, you selected the network device (or port) that represents your main Internet connection. Now, you need to select the port that other computers will use to connect to your Mac, in order to share its main connection.

Depending on which network port you have selected as your active connection, the list of available devices in the To computers using box at the lower left changes to show only the devices available for Internet sharing. For instance, the Internal Modem option never appears in this box because a modem can't be used to connect a local-area network of other computers to the Internet. AirPort can be used for connecting to the Internet or for sharing the connection to other computers, but not both. Ethernet, however, can be used both to connect to the Internet and to share the connection with other computers.

Select the check box next to each network port to select the ports you want to use for Internet sharing. You can select more than one network port at once, if (for instance) you want other computers to be able to connect to your Mac via both Ethernet and AirPort and share your Mac's modem connection.

A dialog sheet appears, warning you that many ISPs do not allow you to "sublet" your Internet connection to other users; for most home networks, this should not be a concern, and you can simply click OK to dismiss the warning. However, if you have any doubts about your ISP's policy regarding sharing your Internet connection, you should check with the ISP before enabling this feature.

NOTES

Ethernet can be used both as your main connection method, and as the shared port for other computers.

If you select AirPort for Internet Sharing, you will want to set up your AirPort options (click the AirPort Options button). The sheet that appears allows you to define a name for your network, select an 802.11 channel, or enable WEP encryption (Wired Equivalent Privacy, wherein your AirPort traffic is scrambled so other wireless users can't intercept it) and set the password required for computers to join your AirPort network.

5.
Start Internet Sharing

When you have selected at least one network port to use for sharing your connection, you can click Start to create the network and begin sharing the connection. You can then connect all the other computers to the network using the same type of device that you're using to share the connection.



MAC OS X Tiger in a Snap
Mac OS X Tiger in a Snap
ISBN: 0672327066
EAN: 2147483647
Year: 2001
Pages: 212
Authors: Brian Tiemann

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