July/August 2003

An Introduction to Wireless Networking

Not so long ago, the University of Nebraska embarked on an effort to wire the entire Lincoln campus. On the same campus today you are likely to find students and faculty tapping into the Internet without the aid of network wires. The availability of wireless access to the Internet is expanding not only on the UNL campus, but in public areas, businesses and homes across the country.

The A-B-G’s of Wireless Networks

To connect to a wireless network, a computer needs a wireless network card and needs to be relatively close to a wireless network access point (AP).

Very generally speaking, the numeric sequence 802.11 identifies one of several official standards for wireless networks that are casually referred to as Wi-Fi technology. The most widely deployed and commonly used standard is 802.11b, which allows for a maximum of 11 Mbps connection at a frequency of 2.4GHz — a speed that rivals your standard 10Mbps Ethernet wall connection. Even though the advertised range of 802.11b is 300 feet, distance and obstacles such as walls (especially concrete ones or those held in place with metal studs) can cause the connection to scale back to 5.5, 2 or even 1 Mbps within short distances.

Nearly all public AP’s are 802.11b and until recently nearly all wireless network cards on the market were as well. In June the IEEE approved the 802.11g standard which allows for up to 54Mbps connections at the same 2.4GHz frequency and complete backward compatibility with 802.11b. Backward is the operative word here since any connection that is of the slower vintage whether it’s the card or the access point will rule the day.

Another new, competing standard is 802.11a which also promises to deliver 54Mbps wireless connectivity. 802.11a networks operate at a frequency of 5GHz, unencumbered by—and incompatible with—existing 802.11b and emerging 802.11g networks. To allow for all three types of cards to connect in a single location (a, b and g) two AP’s, one at 2.4GHz and one at 5GHz, would need to be in place. The future, as always, is murky.

Many new laptops are shipping with 802.11g cards which give them backward compatibility to most existing networks and the opportunity to take advantage of an 802.11g future should one unfold. If you are just now purchasing your first wireless network card or access point, 802.11g looks like a good starting point.

Security

Being able to connect to a network not limited by the number or location of active network jacks can be a magical experience for the first-time wireless user. Usually something so easy and flexible to use is equally as easy and flexible to abuse. It turns out that anyone with a wireless card could gain access to a network and all its resources at anytime, as long as they are in range of the network AP. Letting just anyone have access inside a network constitutes a security breech.

There are few ways to limit access to wireless networks.

• Access points can be set up to require password authentication, but the same password would have to be distributed to every potential user which is an unlikely way to let network administrators sleep better at night.
• Another mechanism that is often used is WEP (Wireless Encryption Protocol) that requires matching software “keys” on the AP and connecting computer. Managing encryption keys becomes a mammoth task if more than a few users are involved.
• A common way to limit access to wireless networks is to provide the AP with a list of trusted network cards. Each wireless network card, like its Ethernet counterpart, comes with a unique identifier — a MAC address (Media Access Control). Only computers with approved MAC addresses are allowed to connect to the access point. MAC address filtering is not a foolproof method of limiting access to wireless networks but it does strike a good balance between manageability and security for a campus, small business or home network.
• New more robust security schemes are presently in the works.

Before leaving the subject of security realize that in order to make a wireless connection, both the AP and wireless device need to behave like miniature radio transmitters to perform their magic. For the most part these broadcasts include all network traffic between you and the server and are transmitted unencrypted within the entire range of the connecting device and access point.

To illustrate just what this means consider a recent technology conference where a gifted programmer demonstrated a software “art form” that involved sampling all transmissions in the local wireless network at the conference and publicly projecting a collage of images assembled from sniffing (or spying on) the real-time web browsing activity of the conference participants. Whether the conference attendees considered this “art” or an invasion of privacy may be unclear, but that wireless connections can be insecure was made crystal clear.

What can be done? The WEP solution mentioned above can help by providing an encrypted wireless connection but at present many of the encryption schemes are weak and relatively easy to overcome by the determined sniffer. For the most part, the best way to deal with this issue is to use encrypted processes between computers when logging into sensitive resources. Avoid using passwords on network resources unless you know the computer-to-computer transfer is secure. For instance secure websites that are prefixed with https: create an encrypted connection between the server and computer that even if intercepted would be impossible to decipher by someone sniffing a wireless network. For the time being, open and unencrypted wireless networks are the reality and wireless users need to behave accordingly.

When You’re Hot You’re Hot

University of Nebraska Access

Enough dreary information about a technology that is just plain exciting. So exciting, in fact, that any area allowing public wireless Internet access is often referred to as a “hot spot.” The University of Nebraska is home to a number of “hot spots” and that number is growing. Both City and East Campus Unions have large areas that allow wireless access to the University network. In both Unions, notebook computers that can access the wireless network are available for check out.

The priority for deploying wireless access on campus is student focused. Most areas where UNL students are likely to congregate in any significant numbers are priority spots for Wi-Fi deployment. Some of Love Library has access. Soon larger classrooms in Plant Science and Animal Science on East Campus and numerous more on City Campus should also be “hot spots.”

Setting up AP’s for campus networking is a time-consuming process that requires much planning and testing so the process of expanding the campus “hot spots” is likely to take a number of years.

To tap into the University of Nebraska wireless network — presently an 802.11b one – you need to register your wireless network card’s MAC with Information Services (IS) using the Wireless Connection Request Form provided on their home page (www.unl.edu/is/). For faculty and staff, there is a monthly charge of $7/month to keep a MAC address in the allowed access list. Student wireless access is free and there are provisions to allow access to guests and frequent visitors to campus. Financing the University’s wireless network is continuously evolving. For more information about the campus wireless network see the "Wireless Networking" link on the IS FAQs page.

Public Access

Those who tote around computers equipped with wireless network cards are finding more and more public places that provide wireless connections for customers and travelers. Starbucks and McDonald’s are two noteworthy examples of companies deploying or planning to deploy wireless network access in stores across the country. Wi-Fi convenience doesn’t require large corporate backing. The Mill coffee shop in Lincoln’s Haymarket is one of two Nebraska public “hot spots” listed on HotSpotList.com, the definitive guide to the discriminating wireless Internet connoisseur.

Just because a spot is hot, does not mean that access is free. There are a number of business that not only try to recover the cost of providing Wi-Fi networks, but there are some that are trying to make a profit for their trouble. An example would be the PASSYM networks found in hotels including some Embassy Suites. To connect to a PASSYM network one needs only to provide a credit card or pre-paid service card number on the web page that appears when a connection request is made. Without payment the Internet experience will be limited to the PASSYM sales page. Other national access plans are being developed that roughly parallel the deployment and pricing of some major wireless telephone networks. Heavily populated and trafficked areas will be the first places to have access to these services.

Given the range of current Wi-Fi communications (see above) it is unlikely that rural areas would see these sorts of services provided by outside vendors using the present technology. Such limitations are not viewed as obstacles by everyone as many less populated areas are building their own wireless community networks.

Home

Wireless home networks are not expensive and are becoming quite common. I can "see" a number of these networks from my living room but only one of them belongs to me. Wireless Access Points can be purchased at most major electronics stores for less than $150. Wireless network cards for your computer can easily be had for well under $100 a piece.

Setting up a home wireless network is the domain of books, not paragraphs in a newsletter. If you set up a wireless network, remember to use good security (i.e. MAC Address filtering) and honor the terms and conditions of your Internet service provider.

Conclusion

This article is intended to be a very brief and superficial treatment of wireless networks. Much more information is available from the Information Services web site. There are also many fine books and websites on the subject, a good starting point might be O’Reilly (www.oreillynet.com/topics/wireless/802.11). Of course you do not need to be an expert to take advantage of this hot technology with lots of momentum. Now if only we could tap into wireless electricity…other than lightening, of course.

~ Ron Roeber

CIT Information is published by Communications and Information Technology - Computing section, Institute of Agriculture and Natural Resources, University of Nebraska-Lincoln. Newsletter articles may be copied and distributed for nonprofit, educational purposes only and the source must be acknowledged. Direct all correspondence to the editor, Pamela K. Peters (E-mail: pkpeters@unlnotes.unl.edu; Phone: 402/472-5630; FAX: 402/472-5639).

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