Very Important: We cannot stress enough that whenever you create something such as an encryption pass code, password, or WEP key, you need to write it down in your notebook. If you lose it, you might have to reset the wireless router to the factory defaults and start over.

The second way to choose an encryption key is make it up yourself using a random combination of numbers (0-9) and letters (A-F). You must create an exact number of numbers and letters depending on which key length you are trying to create. For example, a 64-bit key has 10 digits, a 128-bit key has 26 digits, and so on (the admin screen where you set this up specifies the number of characters). If at all possible, use the built-in key generator from a passphrase. You will pull your hair out trying to create them by hand.

Very Important: If you have been paying close attention, you might be confused. If each hexadecimal digit in the key is 4 bits, how can a 64-bit key have 10 hexadecimal digits and a 128-bit key have 26 hexadecimal digits? Wouldn't that be 40 and 104 bits, respectively? The answer is that there is also a 24-bit random number that gets added to each key that makes up the other 6 hexadecimal digits in the full key length.

Oh, and remember if you have guests who want to use your network, you will have to give them your passphrase or security key. If you need to, you can always change the key after they leave. You can also have them use a direct (wired) connection into the router, which does not require encryption.

Disable Ad-Hoc Networking
Your wireless-enabled computer has two basic modes of communication: infrastructure and ad-hoc networking. In infrastructure mode, all the computers on the network must communicate through the router. So whether you are talking to the Internet or with another computer on the local network, all your communication traffic goes through the router. This is what most people are and should be doing.

In ad-hoc mode, computers can communicate directly with each other without going through a router or any other device. This is great if, for example, you want to share a file with someone quickly. The bad thing is that if you have this mode enabled, those who know what they are doing can get access to all your files, possibly without you even noticing it. To avoid this, we strongly recommend that you disable this function. If you find yourself in a situation where you need to use this feature (such as visiting a friend's home that only has an ad-hoc network), turn it on for the duration of use and then immediately disable it.

Next: How to do it: Securing Your Wireless Network

About the Authors
Jim Doherty is the director of marketing and programs with Symbol Technologies' industry solutions group. Before Symbol, Jim worked at Cisco Systems, where he led various marketing campaigns for IP telephony and routing switching solutions. Jim holds a B.S. degree in electrical engineering from N.C. State University and an M.B.A. from Duke University.

Neil Anderson is a senior manager in enterprise systems engineering at Cisco Systems and is currently responsible for large corporate customers in the areas of routing and switching, wireless, security, and IP communications. Neil holds a bachelor's degree in computer science.

To contact either author, please email: [email protected] and use Home Network Security Simplified/post question as the subject line.

Title: Home Network Security Simplified ISBN: 1-58720-163-1 Authors: Jim Doherty, Neil Anderson Chapter 2: Tip 2: Secure Your Wireless Network Published by Cisco Press

Reproduced from the book Home Network Security Simplified. Copyright [2006], Cisco Systems, Inc. Reproduced by permission of Pearson Education, Inc., 800 East 96th Street, Indianapolis, IN 46240. Written permission from Pearson Education, Inc. is required for all other uses.

*Visit Cisco Press for a detailed description and to learn how to purchase this title.

Another article by the same authors: Voice over IP--The Basics