Wireless-B Ethernet Bridge
Appendix B: Wireless Security
A Brief Overview
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What Are the Risks?
Computer network hacking is nothing new. With the advent of wireless networking, hackers use methods both old and new to do everything from stealing your bandwidth to stealing your data. There are many ways this is done, some simple, some complex. As a wireless user, you should be aware of the many ways they do this.
Every time a wireless transmission is broadcast, signals are sent out from your wireless PC or access point, but not always directly to its destination. The receiving PC or access point can hear the signal because it is within that radius. Just as with a cordless phone, cellular phone, or any kind of radio device, anyone else within that radius, who has their device set to the same channel or bandwidth can also receive those transmission.
Wireless networks are easy to find. Hackers know that, in order to join a wireless network, your wireless PC will typically first listen for “beacon messages”. These are identifying packets transmitted from the wireless network to announce its presence to wireless nodes looking to connect. These beacon frames are decrypted and contain much of the network’s information, such as the network’s SSID (Service Set Identifier) and the IP address of the network PC or access point. The SSID is analogous to the network's name. With this information broadcast to anyone within range, hackers are often provided with just the information they need to access that network.
One result of this, seen in many large cities and business districts, is called “Warchalking”. This is the term used for hackers looking to access free bandwidth and free Internet access through your wireless network. The marks they chalk into the city streets are well documented in the Internet and communicate exactly where available wireless bandwidth is located for the taking.
Even keeping your network settings, such as the SSID and the channel, secret won’t prevent a hacker from listening for those beacon messages and stealing that information. This is why most experts in wireless networking strongly recommend the use of WEP (Wireless Equivalent Privacy). WEP encryption scrambles your wireless signals so they can only be recognized within your wireless network.
Appendix B: Wireless Security
Figure B-1: Warchalking
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A Brief Overview