Connecting Clients to a Wireless Network

Tuesday Nov 28th 2000 by Brien M. Posey

In the second part of this series, you'll learn how to connect wireless clients and how to ensure wireless security.

In Part 1 of this series ( Wireless Networking Benefits and Hardware Requirements ), I discussed the basic operations of a 3Com Air Connect hub. However, you're probably wondering how the clients connect to this hub. In this article, I'll explain the process of connecting clients to a wireless network. I'll then go on to address the issue of wireless security.

Wireless Client Hardware

As you might have guessed, wireless clients must have a wireless network card. At the time I created my wireless LAN, I paid about $2,000 for a wireless network starter kit. This kit included a wireless hub and three PCMCIA network cards. You can see one such card in Figure 1. As you can see, it looks exactly like any other PCMCIA network card except for the black antenna attached to the end of the card. 3Com also sells wireless PCI network cards, so you can attach standard PCs to a wireless network.

Figure 1
Figure 1: A wireless network card is necessary for attaching clients to a wireless network.

Installing a wireless network card is similar to installing any other type of network card. Before you set up your first client, though, you must configure the hub. You do so by attaching the hub to a serial port and using any terminal program (such as Hyper Terminal) to attach to it. Once you've initiated communications with the hub, you'll see a configuration summary screen similar to the one shown in Figure 2.

Figure 2: You must configure the hub before its first use.

As you can see in the figure, you can set a wide variety of options. However, some of these options are more important than others. For example, I highly recommend assigning a password to the hub. Doing so prevents people from making configuration changes. (You'll see why this is so important later on.)

While you're in the configuration mode, you must also assign the hub a static IP address. Although the hub requires a static address, you don't necessarily have to use an address that's registered through a DNS server.

Finally, you must set a WLAN service area. The WLAN service area is simply a number that identifies hubs and wireless PCs as belonging to the same wireless network. That way, if your next-door neighbor installs a wireless LAN, your clients won't try to connect to that network unless both networks have the same WLAN service area number.

The configuration process varies between different brands of wireless hubs. However, on 3Com hubs, the process is very simple: Simply press Esc, and the terminal session will switch from a summary screen to a menu screen similar to the one shown in Figure 3. You can use this menu to configure any of the hub's options.

Figure 3: The wireless hub is menu-configurable.

Once the hub has been configured, mount it in its permanent location. If appropriate, attach a patch cable to bridge the wireless LAN to your Ethernet LAN. You're now ready to attach clients. The process of installing a wireless network card is identical to that of installing any other network card, with one exception. During the configuration process, the network card's driver will ask you for a WLAN service area number. Simply supply the number that you used on the hub, and you're in business.

Once you've connected your first wireless client and have verified that the connection is working, your next concern is security. After all, your precious data is floating through the air, where it can be intercepted by anyone with a wireless network card and your WLAN service area number. Fortunately, the Air Connect hub supports encryption.

Of course if you've already mounted your hub on the ceiling or another difficult-to-reach location, it might be hard to attach a serial cable to configure the hub's security. Fortunately, there's an easier way. Earlier I mentioned that it was important to assign a password to the hub. You should do so because the hub contains a built-in Web server. Simply enter the hub's IP address in any Web browser, and you can access the hub's Web server. You can then make any necessary security modifications without having to use a serial cable. In fact, the Web interface, shown in Figure 4, is easier to use than the terminal session you used for the initial configuration process.

Enabling Encryption

Figure 4: The Air Connect hub contains a built-in Web server that lets you reconfigure the hub through any Web browser.

Once you've enabled encryption, you're ready to start adding more clients. Each wireless hub can support up to 63 clients. I've heard that as you approach the client limit, communications can slow down. However, I've run up to three clients off my hub and never experienced a slowdown.

Adding More Clients



You may wonder what happens if you wander out of range while connected through a wireless session. Believe it or not, you don't have to worry about doing so, even if your building is too large to be completely serviced by a wireless hub. That's because wireless network cards work similarly to cellular phones: If they sense that the signal is getting weak, they will search for a stronger signal. Therefore, it's possible to install multiple wireless hubs. As your wireless users stroll through the building, their computers can engage in active roaming as they switch from hub to hub.


As you can see, setting up a wireless network is a fairly simple process. In this article series, I've introduced you to the hardware necessary for building a wireless LAN. I then went on to give you a preview of the configuration process and discussed some of the security issues that you'll face when building a wireless LAN. //

Brien M. Posey is an MCSE who works as a freelance writer. His past experience includes working as the director of information systems for a national chain of health care facilities and as a network engineer for the Department of Defense. Because of the extremely high volume of e-mail that Brien receives, it's impossible for him to respond to every message, although he does read them all.

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