Scenario: WIRELESS NETWORKING IN ACTION: CREATING A WIRELESS LAN FOR HOME

Sam has three computers, a nice multifunction printer (print/fax/scan/copy), and a high-speed Internet connection at home. He would like to connect all three compu- ters to the Internet and the printer, but he does not want to install any wires because the computers are located on different floors of his house. So Sam has decided to install a wireless local area network. Let us follow Sam as he makes the many decisions necessary to install a wireless network.

Sam first needs to determine which wireless LAN technology his devices sup- port. Recall that four approved technologies exist for wireless LANs: IEEE 802.11b, 802.11a, 802.11g, and 802.11n. IEEE 802.11b was the first standard approved (in 1999) for use with wireless LANs. It transmits signals at 2.4 GHz for roughly 50 meters (150 feet) between access point and wireless device. IEEE 802.11b theoretically transfers data at 11 Mbps. Its actual data transfer speed, however, is approximately 5 Mbps. IEEE 802.11a was the second standard approved in 2002. It transfers data at a theoretical speed of 54 Mbps (with an actual speed of roughly half that) using the 5-GHz frequencies. Because of the higher frequencies, 802.11a can transmit for only about half the distance of 802.11b. To complicate matters, 802.11a and 802.11b are not compatible. The third standard approved was IEEE 802.11g, in 2003. This standard transmits at the same frequencies as 802.11b (2.4 GHz) but has a theoretical transfer speed of 54 Mbps (with an actual speed of approximately half that). It is compatible with 802.11b and has the same transmission distances, roughly 50 meters. Finally, 802.11n was approved in 2009 and can transfer data in the hun- dreds of Mbps. Many if not most of the laptops and desktops sold today support all four wireless technologies. Older equipment may only support 802.11b/a/g. If any of Sam’s computers do not have wireless NICs installed, he will have to purchase a wireless NIC card to install on a desktop, or a wireless NIC device that can be plugged into a USB connector on a laptop.

Now Sam needs to have a wireless access point, but he has read that there are also devices called wireless routers and gateways. What is the difference? If you already have a wired network at home (a modem to connect to the high-speed Inter- net and a router to interconnect the various workstations), then all you need is a wireless access point. Plug in the access point, connect it to your existing router, install the security software, and you should be all set. If you have the high-speed Internet connection but nothing else, you can purchase a wireless router. A wireless router acts as both a router and a wireless access point. If you don’t even have a high-speed Internet connection yet, you might consider installing a gateway. A gateway is often a combination of a high-speed modem, router, and wireless access point—all three devices rolled into one. Many companies that provide Internet service into the home will provide you with a wireless gateway device for a monthly fee or no fee at all. A potential problem with buying your own high-speed modem (as part of a gateway) is compatibility with the high-speed Internet service. Make sure you check with your Internet service provider before you purchase your own modem.

Sam already has a high-speed Internet service, but no wireless router, so he deci- des to purchase a wireless router, making sure the router has security options such as WPA or WPA II. When installing the router, he immediately changes the default net- work name and administrator’s password to minimize the chance of someone hacking into his wireless network. One additional security option Sam looked for was Stateful Packet Inspection (SPI). A router running SPI makes sure that every incoming packet corresponds to an outgoing request that Sam has made, and not someone next door “stealing” Sam’s free radio transmissions.

What about the operating system on his workstations? Does Sam need a net- work operating system such as Linux or Windows Server? No, Sam does not need anything as powerful as a network operating system, even though he is creating a network of wireless devices. Many recent desktop operating systems such as Win- dows 7 or Mac OS X have a provision for supporting wireless workstations. Sam might have to use the Control Panel in the operating system to select Internet Proto- col TCP/IP for the connection, and tell the operating system how the IP address for this device will be obtained. Instructions like these are commonly included with the wireless router and network interface cards, and are not difficult to follow.

Does Sam need any additional network support software? He will definitely need some form of antivirus software to protect his machines from viruses, and it may not be a bad idea to install anti-spam and anti-spyware software at the same time. Security assessment software is always useful, especially with wireless devices and Internet access. Sam also plans to use the firewall software that came with the router and set the security options to protect his computers and his data.

Sam should be ready to use his new wireless network. All devices have been configured for wireless LAN communications (including the printer), as well as the wireless router and security software. Now Sam can surf the Internet from any room in his house, maybe even from the backyard, next to the pool.

Summary:

■ The wireless topology allows a highly flexible placement of workstations and requires no wiring to transmit and receive data.

■ CSMA/CA is the medium access control software that allows wireless devices to connect to access points.

■ A network operating system has several additional functions not normally found in an operating system. For example, it can:

■ Manage one or more servers

■ Maintain a file system of data sets, applications, user profiles, and

network peripherals
■ Coordinate all resources and services available

■ Process requests from users

■ Prompt users for network login, validate accounts, apply restrictions, and

perform accounting functions

■ Manage one or more network printers

■ Manage the interconnection between local area networks

■ Manage locally connected users and remotely connected users

■ Support system security and client/server functions

■ Support Web page development and Web server operations

■ Novell NetWare (now called Open Enterprise Server) was the first popular network operating system with a powerful directory service (NDS), and was very good at performing file and print serving.

■ Windows NT was Microsoft’s first popular network operating system (and is now called Windows Server), was very good at supporting client/server applications, and was based on the domain. Windows Server represents a significant advance- ment over NT and includes the powerful directory service Active Directory.

■ UNIX is an older operating system that is stable, fast, and capable of running on a variety of platforms.

■ Linux is a derivative of UNIX that shares UNIX’s features of stability and speed as well as low cost and the capability to run on a variety of platforms.

■ Mac OS X Server is another derivative of UNIX and, like Linux, shares UNIX’s features of stability and speed. It supports both Macintosh and PC workgroups.

■ The server is the computer that stores software resources such as the network operating system, computer applications, programs, data sets, and databases, and provides one or more services to connected users.

■ Many servers can perform one or more levels of RAID. RAID is designed to provide redundant backup of data onto multiple hard disk drives.

■ Many types of software programs support a local area network. These include utility programs and Internet software tools.

■ Software licensing agreements are an important part of local area network software installation. The most common forms are single-user-single-station, single-user-multiple-station, interactive user, system-based, site, corporate licenses, and General Public License.

■ Many types of hardware devices are necessary to support a local area net- work, including hubs, switches, and routers; uninterruptible power supplies and surge protectors; tape drives; network attached storage; printers and print servers; media converters; workstations; and servers.

In the scenario described, Sam makes a number of decisions: which wireless LAN technology to utilize (802.11a, b, g, & n), whether he needs a wireless NIC, whether to utilize a wireless router or gateway, whether to change the default username and password, what operating system to use on his workstations, and whether he needs any additional network support software.

Those with computer networking and IT backgrounds often makes these decisions with confidence based on prior knowledge and experience, but for those with minimal experience, such decisions can be overwhelming. It is not uncommon for buyers to make poor choices without understanding why those decisions matter, or to delegate those choices to a rep or associate, or even decide purely on the packaging and its claims. Unfortunately, not understanding the consequences of those decisions can expose anyone who uses Sam’s wireless network to substantial risk that can be exploited.

Which decision(s) that Sam made do you think was(were) the most important one(s), and why?

Why do you think so many average consumers don’t factor security into their buying decisions?

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