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ing the address releases it. Each time when you restart your computer ” or
on a periodic basis if you leave your computer on all the time ” the DHCP
server will renew the lease, allowing the computer to keep the IP address that
it has been given.




Domain Name System (DNS) servers
When the DHCP server assigns an IP address, it server addresses will be supplied by your ISP™s
also specifies the IP addresses for Domain DHCP server and will be passed on by your
Name System (DNS) servers and for a default home network™s DHCP server to each worksta-
gateway. Domain names are text-based names tion. The default gateway takes care of sending
that represent one or more registered IP network traffic to devices that have IP
addresses used on the Internet. When you type addresses outside the local subnet. The wire-
a Uniform Resource Locator (URL) in your Web less Internet gateway device or the cable/DSL
browser, DNS servers translate the text-based router that you installed in your wireless net-
domain names in the URL into the equivalent IP work is the default gateway for each of the
addresses. You don™t have to know the IP computers on your network.
addresses, just the domain names. The DNS
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Chapter 9: Setting Up Internet Sharing


Windows 9x
If your computer is running the Windows 9x (95, 98, 98 SE, or Me) operating
system, the steps in this section are for you. To instruct the network adapter
to obtain its IP address automatically from a DHCP server, follow these steps:

1. Choose Start➪Settings➪Control Panel.
2. Double-click the Network icon in the Control Panel.
The Network dialog box appears.
3. In the Configuration tab, highlight the TCP/IP item for the network
adapter that you want to configure and then click the Properties
button.
For example, Figure 9-2 shows the Network dialog box in Windows 9x
with the TCP/IP item for Microsoft Broadband Networking Wireless USB
Adapter selected.




Figure 9-2:
The
Network
dialog box in
Windows
9x.



The TCP/IP Properties dialog box appears, as shown in Figure 9-3.
4. On the IP Address tab, select the Obtain an IP Address Automatically
radio button and then click OK.
You™re returned to the Network dialog box.
5. Click OK again to return to the Control Panel.
6. Close the Control Panel.
Depending on your version of Windows, you might be prompted to
insert the Windows CD in the CD drive.
170 Part III: Installing a Wireless Network




Figure 9-3:
The TCP/IP
Properties
dialog box in
Windows 9x.



7. Insert the Windows CD and then click OK.
Windows copies the needed files to your computer™s hard drive and then
has to restart the computer before the change takes affect. When the
computer restarts, Windows will lease an IP address from your net-
work™s DHCP server.



Windows 2000
If the computer is running the Widows 2000 operating system, follow these
steps to set the network adapter to obtain its IP address automatically from a
DHCP server:

1. Choose Start➪Settings➪Network and Dial-up Connections.
The Network and Dial-up Connections window appears, as shown in
Figure 9-4.
2. Highlight the Local Area Connection item for the network adapter that
you want to configure.
In Figure 9-4, the wireless network interface adapter is listed as
ORiNOCO PC Card.
3. Choose File➪Properties.
The Local Area Connection Properties dialog box appears.
4. Highlight the Internet Protocol (TCP/IP) option and then click the
Properties button.
The Internet Protocol (TCP/IP) Properties dialog box appears, as shown
in Figure 9-5.
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Chapter 9: Setting Up Internet Sharing




Figure 9-4:
The
Network
and Dial-up
Connections
window in
Windows
2000.




Figure 9-5:
The Internet
Protocol
(TCP/IP)
Properties
dialog box in
Windows
2000.



5. On the General tab, select both the Obtain an IP Address
Automatically and the Obtain DNS Server Address Automatically
radio buttons.
172 Part III: Installing a Wireless Network

6. Click OK to return to the Local Area Connections dialog box and then
click OK again to return to the Network and Dial-up Connections
window.
7. Close the Network and Dial-up Connections window.
Windows 2000 applies the change to the network settings and obtains an
IP address for the network adapter from your network™s DHCP server.



Windows XP
If your computer is running the Windows XP operating system, follow these
steps to set the network adapter to obtain its IP address automatically from a
DHCP server:

1. Choose Start➪Network Connections.
If Network Connections doesn™t appear in the Start menu, choose
Control Panel and then double-click the Network Connections icon in the
Control Panel.
The Network Connections window appears, as shown in Figure 9-6.
2. In the LAN or High-Speed Internet section of the Network Connections
window, highlight the Wireless Network Connection item for the net-
work adapter that you want to configure.
For example, in Figure 9-6, the wireless network interface adapter device
is listed as ORiNOCO PC Card (5 Volt) in the Network Connections
window.
3. Choose File➪Properties.
The Wireless Network Connection Properties dialog box appears.
4. On the General tab, highlight the Internet Protocol (TCP/IP) option,
and then click the Properties button.
The Internet Protocol (TCP/IP) Properties dialog box appears, as shown
in Figure 9-7.
5. On the General tab, select both the Obtain an IP Address
Automatically and the Obtain DNS Server Address Automatically
radio buttons and then click OK.
You™re returned to the Wireless Network Connection Properties dialog box.
6. Click OK again to return to the Network Connections window and
then close that window.
Windows XP applies the change to the network settings and obtains an
IP address for the network adapter from your network™s DHCP server.
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Chapter 9: Setting Up Internet Sharing




Figure 9-6:
The
Network
Connections
window in
Windows
XP.




Figure 9-7:
The Internet
Protocol
(TCP/IP)
Properties
dialog box in
Windows
XP.




Mac OS
If the computer is running the Mac OS 9.x operating system, follow these
steps to set the network adapter to obtain its IP address automatically from a
DHCP server:
174 Part III: Installing a Wireless Network

1. From the Apple menu, display the Control Panels list, select TCP/IP,
and then click OK to display the TCP/IP window.
2. From the Connect Via drop-down menu, choose the network device
that you want to configure.
3. From the Configure drop-down menu, choose Using DHCP Server.
4. Close the TCP/IP window, saving changes when prompted.
Mac OS sends a request to the DHCP server for an IP address and
assigns that address to the network device.

If the computer is running the Mac OS X operating system:

1. From the Apple menu, choose System Preferences and then click the
Network icon to display the Network pane.
2. From the Show menu, choose the network interface adapter that you
want to configure.
3. On the TCP/IP tab (see Figure 9-8), choose Using DHCP from the
Configure menu.
Mac OS sends a request to the DHCP server for an IP address and
assigns that address to the network adapter.




Figure 9-8:
The TCP/IP
tab of the
Mac OS X
Network
pane.
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Chapter 9: Setting Up Internet Sharing


Setting Up Internet Connection Sharing
Internet gateways and cable/DSL routers are certainly the easiest way to
accomplish Internet connection sharing, but we know of a more economical
method ” software-based sharing using an attached PC. We should say, right
up front, that we think that the hardware approach ” that is, using a wireless
Internet gateway or a cable/DSL router ” is the best way to go. But if you
really need to save a few bucks (and we mean only a few because you can get
a router for $50 these days), try this approach. It works, but it™s not as good
as the hardware approach because it can affect the performance of both your
network overall as well as the particular computer that you use for Internet
connection sharing. Windows 98 Second Edition (SE) and later versions of
Windows provide a software-based solution for sharing an Internet connec-
tion over a local area network (LAN). This option is available whether you™re
using a wired network, a wireless network, or a combination of the two.

Software-based Internet connection sharing is not efficient if you have more
than four computers trying to share an Internet connection simultaneously.
The cost of a broadband router is far less than the cost of a dedicated com-
puter in most cases. And broadband routers usually contain other features that
this software connection sharing doesn™t offer, such as port forwarding (Port
Address Translation; PAT) to forward incoming requests to specific machines
based on port, as well as offering a demilitarized zone (DMZ). (A DMZ, in the
network world, is a network zone that has no firewall protection ” we discuss
this more in Chapter 10.) On the other hand, if you have an extra computer lying
around and have time on your hands to maintain it, software-based Internet
connection sharing could be your best option. (We™re still not convinced.)

When you set up a Windows software-based shared Internet connection, you
select one computer to be the Internet connection host ” the computer (run-
ning Windows 98 or later) that is always turned on and always connected to
the Internet so that any other networked computer is able to access the

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