Windows 8 : Managing Mobile Networking and Remote Access - Wireless Networking

When you are working with wireless networks, the most common terms you’ll run across are wireless network adapter and wireless access point. Wireless adapters include PC cards for notebooks, Peripheral Component Interconnect (PCI) cards for desktops, and USB devices (which can be used with notebooks or desktops). However, most of today’s mobile devices have the wireless adapter built in. A wireless adapter uses a built-in antenna to communicate with an access point. Typically, an access point is directly connected to the organization’s physical network and might also function as a network switch or hub itself, meaning it has physical ports that allow direct cable connections as well as wireless connections. Other names for access points include wireless base stations and wireless gateways.

The most widely used wireless network adapters and access points are based on the IEEE 802.11 specification. Wireless devices that are based on this specification can be Wi-Fi certified to show that they have been thoroughly tested for performance and compatibility. Table 1 compares the features of the most used wireless technologies based on IEEE 802.11. As the table describes, there are four standards, and each has its benefits and drawbacks. It should be noted that although 802.11a wireless devices cannot interoperate with 802.11b or 802.11g devices, fewer devices use the 5-GHz range, making it less likely that there will be interference with other types of wireless devices (the majority of which use the 2.4-GHz range).

Newer 802.11 transmission specifications include 802.11n. 802.11n offers speeds up to 540 Mbps and can interoperate with devices using 802.11b and 802.11g. To achieve high transmission speeds, 802.11n can use multiple receivers and multiple transmitters. Each transmitter can transmit one or more streams of data. The more streams of data that a device can use across all transmitters and receivers, the higher the throughput. However, many standard 802.11n devices with multiple transmitters and receivers combine strong, weak, and reflected signals into one data stream to maximize the range.

For added security, IEEE has defined the 802.11i standard. Unlike the 802.11a, 802.11b, 802.11g, and 802.11n standards, the 802.11i standard isn’t about transmission speeds and frequencies. 802.11i is a security standard that you can add to the existing standards. More specifically, it adds security functionality to the radio specifications of 802.11a, 802.11b, 802.11g, and 802.11n. This means that 802.11a network adapters and access points can include the 802.11i security functionality, as can 802.11b, 802.11g, and 802.11n wireless products.

Securing a wireless network is very different from securing a wired network. With a wired network, a cable is used to connect a computer to the network. A user must use a cable to be physically connected to the network and must have access to one of your internal switches or hubs. If an unauthorized person connects a machine to the network, it is fairly easy to determine this and trace the physical cable to the intruder’s computer.

When you install wireless networking, anyone within range of one of your wireless access points has access to your network. Not only can they intercept the wireless signals that are being broadcast, they can also try to crack into the network. The bad news is that it is difficult to locate the intruder because there’s no physical wire to trace. The really bad news is that if intruders can gain access to a wireless access point, they are usually inside your organization’s firewall. To protect the network, you should configure its firewall if one is available and configure the wireless devices to encode all wireless transmissions.

The most basic wireless encryption scheme is Wireless Equivalency Protection (WEP). With WEP, you encrypt data using 40-bit, 128-bit, 152-bit, or higher private key encryption. With WEP, all data is encrypted using a symmetric key derived from the WEP key or password before it is transmitted, and any computer that wants to read the data must be able to decrypt it using the key. In a typical wired environment, the shared key encryption alone is sufficient to safeguard your data. In a wireless environment with high traffic volume, it is possible that someone could successfully break the shared key, and because the shared key doesn’t change automatically over time, the intruder would then have access to your organization’s internal network.

Because WEP provides only the most basic security, its use is strongly discouraged except in cases where no alternative exists. The preferred alternatives to WEP are Wi-Fi Protected Access (WPA) and WPA2. WPA was adopted by the Wi-Fi Alliance as an interim standard prior to the ratification of 802.11i. WPA2 is based on the official 802.11i standard and is fully backward compatible with WPA.

WPA and WPA2 are able to rotate keys for added security and to change the way that keys are derived. By changing the encryption keys over time and ensuring that they aren’t derived in one specific way, WPA and WPA2 can improve security significantly over WEP. WPA-compatible and WPA2-compatible devices can operate in enterprise mode or in a personal, home/small office configuration, as explained in the following points:

When working with WPA and WPA2, keep the following in mind:

Another advanced wireless security technology is Robust Security Network (RSN), which is supported by 802.11i-compatible devices. RSN enables wireless devices to negotiate their authentication and encryption algorithms dynamically. This means that the authentication and encryption algorithms used by RSN-compatible devices can be changed. New authentication techniques and algorithms can be added to address security issues. RSN is based on EAP and AES.

Other than mobile devices with built-in wireless adapters, the two main types of wireless adapters you’ll use are PC cards for notebooks and PCI cards for desktops. These adapters are the easiest to configure—and I’ve found them to be the most reliable. The other type of wireless adapter that you might see is a device that connects to a notebook or desktop computer with a USB cable. When using USB wireless devices, keep in mind that there are several USB specifications, including USB 2.0 and USB 3.0, the faster, newer specification. A wireless device that complies with USB 3.0 must be connected to a USB 3.0 port to function properly and at the speeds you expect.

As part of the installation process, most installation software will help you configure the wireless device. In the process, you may need to specify the name of the wireless network to which you want to connect and the mode in which the wireless device will run. Wireless adapters can run in one of two operating modes:

After you specify the adapter mode, you might need to specify the encryption key that will be used. If your organization uses WEP security, in most cases you will have to type the required encryption key, which is usually referred to as the network key. With WPA/WPA2 security, you most often use a certificate or a smart card to supply the required encryption key.

Once you’ve completed the installation of the device, you should be able to connect over the wireless network. Much like a wired network card, which has an Ethernet connection, a wireless network card has a Wi-Fi connection that is in turn connected to a specific network that is designated as a public network, private network, or domain network. If a computer has both a wired and a wireless connection, it might have two active connections: one to a wired network and one to a wireless network.

Wi-Fi connections provide the following additional details about the network and the connection:

To view the settings for a wireless connection, complete these steps:

Figure 1. Determine the status and signal strength of a wireless network connection.

As with Ethernet connections, Wi-Fi connections have configurable properties. This means that every discussion about configuring network connection properties also applies to Wi-Fi connections. You can do the following:

If you have problems establishing a wireless connection and automated diagnostics can’t resolve the problem, use these tips to help you troubleshoot:

Any wireless access point broadcasting within range should be available to a computer with a wireless adapter. By default, Windows 8 automatically determines the appropriate settings. If a connection requires a password or other credentials, you are prompted for the credentials when you try to connect to the wireless network. You can preconfigure wireless connections for users as well. This enables you to configure different authentication, encryption, and communication options as necessary.

You can preconfigure a connection for a wireless network by completing the following steps:

Typically, when you are within the broadcast range of a wireless network, you won’t need to preconfigure a connection and can instead connect directly, letting Windows determine the correct settings. To connect to a wireless network, complete the following steps: