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wireles network hacks mods - briere D.

briere D. wireles network hacks mods - Wiley publishing, 2005. - 387 p.
ISBN: 0-7645-9583-0
Download (direct link): wirelesnetworkhacks.pdf
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Networks that have ESSID broadcast turned off do not show up on this list, but in the next section of this chapter, we describe some tools that allow you to see them anyway. Also, if you’ve previously associated with an access point and have added it to your preferred network listing, it shows up here even if the broadcast is turned off.
^ Security status: If a network has a Wi-Fi security (encryption) system turned on, this is noted in the network’s entry in the list of available networks. For example, in Figure 6-1, you can see that Opie has WEP encryption turned on, whereas Cherry and Petunia are locked down with the stronger WPA encryption scheme. Not to pick on the neighbor again, but you’ll note that Default has no encryption turned on. That makes the neighbor’s network a good backup should Pat’s cable modem ever go down!
ё You’ll note that there’s no indication of which type of WPA encryption
(Enterprise or Personal) is being used, or whether it’s WPA or WPA 2 (see Chapter 8 for more on these terms). All you’ll see in this dialog box is that a network is WPA (Security-enabled wireless network (WPA)),
WEP (Security-enabled wireless network), or unsecured.
^ Signal strength: Windows also provides a nice graphical representation of signal strength, using those five vertical bars you can see at the far right of Figure 6-1. (The bars are green, but because this is a black-and-white book, you’ll have to trust us on that one.) The more green, the better — if all five bars are green, you have an excellent signal. These bars don’t really tell you all that much info by themselves, but look at Table 6-1 for a translation of bars to SNRs.
If you mouse over the signal strength display and hover your pointer, Windows tells you in words how your signal strength is (we’ve included those words in the table as well). Excellent is best, poor is worst, and the rest are pretty much somewhere in between.
Table 6-1 Translating Windows Signal Strength Indicators
Number of Bars Signal Strength SNR
5 Excellent 26 dBm or above
4 Very good 21 to 25 dBm
3 Good 16 to 20 dBm
2 Low 11 to 15 dBm
1 Very low 10 dBm or below
_______________Chapter 6: Better Living Through Network Monitoring
Using Mac OS X
Figure 6-2:
Showing signal strength in Mac OS X.
Mac OS X doesn’t have a single interface that shows available networks quite as completely as does Windows XP — the interface on the Mac is a bit less involved, but probably also a bit easier. To “sniff” out available networks using OS X, simply open Apple’s Internet Connect application — it’s in your Applications Folder, and may very well be located on the OS X dock.
When Internet Connect is open, click on the AirPort tab. You see a pulldown menu that displays each wireless network within range of your Mac (shown in Figure 6-2). Put another way, it displays each wireless network that has enough signal strength to reach your Mac. This display provides a green bar graph display of signal strength — simply choose another network from the pulldown menu.
^OO AirPort Đž
^ 0 ® T Q
Summary Internal Modem Bluetooth IrDA AirPort VPS
AirPort Power On i Turn AirPort Off )
Network Cherry
Signal Level ||||||||||||| i a
Base Station ID: 00 0F B5 A4 BD 42
Ф Show AirPort status in menu bar
Status: Connected to ’Cherry"
You can streamline this process by putting your AirPort display in the OS X menu bar. Just go to System Preferences (in your Applications folder or on the Dock) and click on Network. In Network, click on the AirPort tab and make sure that the Show AirPort Status in Menu Bar checkbox is selected — if it’s not, select it and click the Apply Now button.
When the AirPort status is in the menu bar, you always see a list of available networks in the menu bar, and you can open Internet Connect by simply using this pulldown menu.
Using wireless client software
Although Windows Zero Config is the easiest way for Windows users to find and examine wireless networks, it’s not the only way. Most wireless network adapters include their own client software that handles network configuration, AP selection, and more.
Part II: Boosting Performance on Your Wireless Network
These client software packages usually offer a network monitoring application that gives you more network information than the software clients that are built into the operating systems. For example, these clients may provide more elaborate signal strength and SNR meters and may even offer some raw data on the actual data throughput across your wireless network (for example, showing bit or packet rates and error rates).
For example, the client software included with NETGEAR’s wireless network adapters, shown in Figure 6-3, shows transmit, receive, or both transmit and receive data rates graphically and numerically (in terms of packets of data per second). It also shows the packet error rate, which, although not identical, is proportional to the BER we discussed earlier in the chapter.
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