CompTIA A_ Certification All-In-One Exam Guide, Seventh Edition - Michael Meyers [427]
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NOTE Many techs shorten the term “MAC address filtering” to simply “MAC filtering.” Either way works.
WEP
Early on, Wi-Fi developers introduced the Wired Equivalent Privacy (WEP) protocol to attempt to ensure that data is secured while in transit over the airwaves. WEP encryption uses a standard 40-bit encryption to scramble data packets. Many vendors also support 104-bit encryption. Note that some vendors advertise 128-bit encryption, but they actually use a 104-bit encryption key. Unfortunately, WEP encryption includes a flaw that makes it extremely vulnerable to attack. Although better than no encryption at all, keep in mind that WEP will not keep out a knowledgeable intruder.
One important note to consider is that WEP doesn’t provide complete end-to-end encryption. WEP provides encryption only between the WAP and the wireless device. Encryption is stripped from the data packet as it travels “up” through the subsequent network layers. For true end-to-end encryption, you need to upgrade to WPA or WPA2.
WPA
The Wi-Fi Protected Access (WPA) protocol addresses the weaknesses of WEP and acts as security protocol upgrade to WEP. WPA offers security enhancements such as an encryption key integrity-checking feature and user authentication through the industry-standard Extensible Authentication Protocol (EAP). EAP provides a huge security improvement over WEP encryption. After all, MAC addresses are fairly easy to “sniff” out, because they’re transmitted in unencrypted, clear text format. User names and passwords are encrypted and, therefore, much more secure. Even with these enhancements, WPA was intended only as an interim security solution until the IEEE 802.11i security standard was finalized and implemented.
WPA2
Today, Macintosh OS X and Microsoft Windows support the full IEEE 802.11i standard, more commonly known as Wi-Fi Protected Access 2 (WPA2), to lock down wireless networks. WPA2 uses the Advanced Encryption Standard (AES), among other improvements, to provide a secure wireless environment. If you haven’t upgraded to WPA2, you should.
Speed and Range Issues
Wireless networking data throughput speeds depend on several factors. Foremost is the standard that the wireless devices use. Depending on the standard used, wireless throughput speeds range from a measly 2 Mbps to a snappy 100+ Mbps. One of the other factors affecting speed is the distance between wireless nodes (or between wireless nodes and centralized access points). Wireless devices dynamically negotiate the top speed at which they can communicate without dropping too many data packets. Speed decreases as distance increases, so the maximum throughput speed is achieved only at extremely close range (less than 25 feet or so). At the outer reaches of a device’s effective range, speed may decrease to around 1 Mbps before it drops out altogether.
Speed is also affected by interference from other wireless devices operating in the same frequency range—such as cordless phones or baby monitors—and by solid objects. So-called dead spots occur when something capable of blocking the radio signal comes between the wireless network nodes. Large electrical appliances such as refrigerators are very effective at blocking a wireless network signal. Other culprits include electrical fuse boxes, metal plumbing, air conditioning units, and similar objects.
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NOTE You can see the speed and signal strength on your wireless network by looking at the wireless NIC’s properties.
Wireless networking range is difficult to define, and you’ll see most descriptions listed with qualifiers, such as “around 150 feet” and “about 300 feet.” This is simply because, like throughput speed, range is greatly affected by outside factors. Interference from other wireless devices affects range, as does interference from solid objects. The maximum