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Wireless Networking - Additional Notes

Wireless networking overview
Wireless networking is a way to connect computers or other devices, either in your home or across long distances, using infrared light or radio frequency signals. Devices commonly used for wireless networking include desktop and laptop computers, hand-held computers, personal digital assistants (PDAs), mobile phones, pen-based computers, and pagers. Wireless networking is useful in many situations. For example, if you are away from your computer, you can use your mobile phone to read and respond to e-mail. If you travel with a laptop computer, you can connect to the Internet through wireless access points installed in airports, hotels, and other public locations. You can also synchronize data and transfer files between two computers or between a computer and another device.

Wireless local area networks (WLANs) are often used in corporate or campus buildings, or in airports. WLANs are also used in home or small office networks. There are two types of WLAN:

  • A local area network that uses access points to connect computers and devices on the network. This is also called an infrastructure network.
  • A computer-to-computer local area network (also called an ad hoc network) with several users in a limited area, such as a conference room. This type of network does not use an access point.

When your computer is in range of a wireless network, Windows XP sends you a message, which appears in the notification area on your screen. You can click the message to see a list of wireless networks and then select a wireless network to connect to. If you are traveling, you can get a list of available wireless networks in the area where you will be staying by entering the city, state or province, and postal code for that area.

Sometimes when you connect to a wireless network, you are prompted to enter a network key (also called a WEP key, or wired equivalency privacy key). This key is like a password that you need to gain access to the network. In some cases, the key might be provided to you by the network administrator. In other cases, you might be asked to create a key.

To connect to an available wireless network

  1. Open Network Connections.
  2. Click the wireless network connection icon, and then, under Network Tasks, click View available wireless networks.
  3. Choose the wireless network from the list that appears, and then click Connect.
    • If the network is one that supports Wireless Provisioning Services, such as a public wireless network or a corporate network, you might be asked to download additional files that will allow your computer to connect to the network.
      If the Web site listed in the dialog box is one that you trust to provide you with this information, click Download. Otherwise, click Cancel and choose a different network to connect to.
    • Once the files are downloaded (or if they were previously downloaded), follow the instructions in the Wireless Network Registration Wizard.
  4. If the network you choose is security-enabled, one of the following will occur:
    • If the network key is automatically provided by your network or system administrator (that is, the network supports IEEE 802.1x), the connection will be made automatically.
    • If the network key is not automatically provided, in Network key, type the key.
  5. To configure other wireless network connection settings, or if you are having difficulty making a connection to the wireless network that you selected, under Related Tasks, click Change advanced settings, select the wireless network that you want to configure, and then click Properties. If the wireless network is not in the list, click Add.


  • To open Network Connections, click Start, point to Settings, click Control Panel, and then double-click Network Connections.
  • Some wireless networks might not appear on the list. For example, a public Internet service provider (ISP) can be configured to use another provider's wireless network name. In that case, you might see only the public ISP in the list of wireless networks. To show all wireless networks, click Show wireless access point names.

Configuring wireless network client computers
Automatic wireless network configuration uses the IEEE 802.11 standard for wireless networks and makes it easy to access those networks. When you enable automatic wireless network configuration on your computer, you can access different wireless networks without reconfiguring the network connection settings on your computer for each location. As you move from one location to another, Windows searches for available wireless networks and notifies you when there are new wireless networks available for you to connect to. After you select a network to connect to, your wireless network adapter is updated to match the settings of the wireless network, and Windows attempts to connect to that wireless network.

With automatic wireless network configuration, you can create a list of preferred wireless networks. You can also specify the order in which to attempt connections to those networks.

Wireless network types
You can choose from the following wireless network types:

Access point (infrastructure)
In access point wireless networks, wireless stations (devices with radio network cards, such as a portable computer or personal digital assistant) connect to wireless access points. These access points function as bridges between wireless stations and the existing network distribution system (network backbone). As you move from one location to another, and the signal for one wireless access point weakens or the access point becomes too busy, you can connect to a new access point. For example, if you work in a large corporation, your wireless device can connect to several different access points as you move between different floors of a building or different buildings in a campus. As a result, you maintain uninterrupted access to network resources.

Computer-to-computer (ad hoc)
In computer-to-computer wireless networks, wireless stations connect to each other directly, rather than through wireless access points. For example, if you are in a meeting with co-workers, your wireless device can connect to the wireless devices of your co-workers, and you can form a temporary network.

Any available network (access point preferred)
In any available network wireless networks, a connection to an access point wireless network is always attempted first. If an access point network is not available, a connection to a computer-to-computer wireless network is attempted. For example, if you use your laptop at work in an access point wireless network, and then take your laptop home to use in your computer-to-computer home network, automatic wireless network configuration will change your wireless network settings so that you can connect to your home network.

802.11 security
Security options for 802.11 include authentication and encryption services based on the Wired Equivalent Privacy (WEP) security services used to protect 802.11 networks from unauthorized access, such as eavesdropping. With automatic wireless network configuration, you can specify that a network key be used to verify access to the network. You can also specify that a network key be used to encrypt your data as it is transmitted over the network.

The wireless network adapter in your computer might support the Wi-Fi Protected Access (WPA) security protocol. WPA provides stronger encryption than WEP. With WPA, the network keys on networked computers and devices are automatically changed and then authenticated regularly, which provides greater security than WEP.

To use WPA, your wireless network adapter must support it. To find out if you can use WPA on your wireless network, check the manufacturer's Web site for information about your device. The manufacturer might have software or a driver that you can download and install.

Network keys
When you enable WEP, you can specify that a network key be used for encryption. A network key might be provided for you automatically (for example, it might be provided on your wireless network adapter), or you can specify the key by typing it yourself. If you specify the key, you can also specify the key length (40 bits or 104 bits), key format (ASCII characters or hexadecimal digits), and key index (the location where a specific key is stored). The longer the key length, the more secure the key. Every time the length of a key is increased by one bit, the number of possible keys doubles.

Under 802.11, a wireless station can be configured with up to four keys (the key index values are 0, 1, 2, and 3). When an access point or a wireless station transmits an encrypted message using a key that is stored in a specific key index, the transmitted message indicates the key index that was used to encrypt the message body. The receiving access point or wireless station can then retrieve the key that is stored at the key index and use it to decode the encrypted message body.

802.1x authentication
For enhanced security, you can enable IEEE 802.1x authentication, which provides authenticated access to 802.11 wireless networks and to wired Ethernet networks. IEEE 802.1x authentication minimizes wireless network security risks, such as unauthorized access to network resources and eavesdropping. It provides user and computer identification, centralized authentication, and dynamic key management. The support that IEEE 802.1x provides for Extensible Authentication Protocol (EAP) security types allows you to use authentication methods such as smart cards and certificates. EAP security types include EAP-TLS, Protected EAP (PEAP) with EAP-TLS, and Microsoft Challenge Handshake Authentication Protocol version 2 (MS-CHAPv2).

With IEEE 802.1x authentication, you can specify whether the computer attempts authentication to the network if the computer requires access to network resources whether a user is logged on or not. For example, data center operators who manage remotely administered servers can specify that the servers should attempt authentication to access the network resources. You can also specify whether the computer attempts authentication to the network if user or computer information is not available. For example, Internet service providers (ISPs) can use this authentication option to allow users access to free Internet services, or to Internet services that can be purchased. A corporation can grant visitors limited guest access, so that those visitors can access the Internet, and not confidential network resources.


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