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| WLAN Analyzer and Protocol Decoder - CommView for WiFi |
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The Scanner window allows you to scan the air for WiFi signals and select a channel to monitor. To start scanning, just click on the Start Scanning button. The scanning process is cyclic, i.e. the program will "listen" for signals on the first channel, then switch to the next channel, and so forth, until it reaches the last channel, after which a new scanning cycle will begin. The scanning process will not stop until Stop Scanning is clicked. To clear the data that has been collected, click Reset. To save the scanning report in HTML format, click Save …. When you are done with scanning and/or if you know the channel on which you want the program to capture packets, select a band from the Band drop-down list (depending on your adapter, the list may contain one or several different bands: 802.11a, 802.11a/n, 802.11a-turbo, 802.11 b/g, 802.11 b/g/n), then select a channel from the Channel drop-down list and click Capture. 
The Options tab allows you to configure a number of scanning options. The following scanning options are available: 
Reset data after each cycle – check this box if you would like the program to clear all the data it has collected before beginning a new scanning cycle. This option has both drawbacks and advantages. The advantage is that resetting data will give you the most up-to-date picture of the ether. For example, if a certain station no longer sends data, it will not show up on the list again. However, the drawback is that if a certain station does not send data actively, e.g. it does so just a few times per minute, the scanner may not "notice" the station each time it scans a certain channel. Furthermore, this station will be removed from the list. Show data in main window while scanning – check this box if you would like the program to display the packets being captured during scanning in the main program's window (on the Nodes, Channels, Packets and Latest IP Connections tabs). If this box is not checked, the packets that are captured while the scanner is working will not be displayed or logged anywhere. Hide wired hosts – check this box if you would like the program to show only wireless hosts and access points. If this box is not checked, the scanner will show both wireless and wired hosts in the segment being scanned. Note that enabling this option may sometimes hide even wireless hosts, as the program needs to capture several data packets to determine if a host is wired or wireless. Active node discovery using PROBE REQUEST – if this box is checked, the program sends PROBE REQUEST packets periodically. Such packets facilitate the discovery of those Access Points that do not broadcast their SSID. Note that using this option may make your adapter transmit packets, so it would no longer be completely stealth. This option is not available for some cards. Seconds per channel – determines the time interval the scanner will listen for data on each of the channels being scanned. Play sound when a new AP or station is detected – check this box and select a WAV file if you want the program to notify you about access points or stations it has found. You can test the selected WAV file by clicking on the button next to the file selection field. Scan 802.11b/g channels and Scan 802.11a channels – these check boxes allow you to select the channels to be scanned. You need to select at least one channel. Depending on your country, your wireless network adapter may not support all the channels shown in this window. If a channel is not supported by your adapter, the corresponding check box will be grayed out. The same applies to the Scan 802.11a channels frame: It will be grayed out if your adapter does not support 802.11a. If your adapter supports 802.11n in the 2.4 GHz band, the Scan 802.11b/g channels frame will be named Scan 802.11b/g/n channels. If your adapter supports 802.11n in the 5 GHz band, the Scan 802.11a channels frame will be named Scan 802.11a/n channels. Depending on the country and regulatory domain set in your adapter, the list of supported channels may vary. This is discussed in the FAQ chapter in detail. About SuperG and SuperAG SuperG/SuperAG is a proprietary throughput enhancement technology introduced by Atheros Communications and supported by a number of hardware vendors (visit www.super-ag.com for more information). SuperG/SuperAG uses packet-bursting, "fast frames," on-the-fly data compression/decompression, and dual-channel bonding to provide throughput enhancement up to 108 Mbps. Depending on the hardware being used, your WLAN may partly or fully work in SuperG/SuperAG mode. SuperG- and SuperAG-enabled hardware typically works in several modes: Super Mode without Turbo, Super Mode with Static Turbo, and Super Mode with Dynamic Turbo. In the 802.11g band, data transmission in Super mode with Static Turbo and Super Mode with Dynamic Turbo is performed over the 802.11g channel 6. However, CommView for WiFi may be unable to capture the wireless traffic if you select the 802.11g channel 6 for monitoring. This is why you have the option of selecting SuperG for monitoring, in which case CommView for WiFi will be able to capture this special kind of frames. Note that the hardware may dynamically switch modes, depending on the network load and other factors, which makes monitoring problematic. In the 802.11a band, data transmission in Super mode with Static Turbo and Super Mode with Dynamic Turbo is performed over special turbo channels. If your adapter used for monitoring supports the 802.11a turbo mode, just select the appropriate band and channel in the drop-down lists. This mode uses a separate set of channels, i.e. channels 42, 50, and 58 are usually turbo channels, while other 802.11a channels are non-turbo ones. There are exceptions to this rule; for example, in Japan, channels 34, 38, 42, and 46 are non-turbo channels. To be able to monitor these channels in Japan, a special country-specific driver build is needed. You can contact us if you need such a driver for Japan or any other country with a non-standard channel set. IMPORTANT: Because SuperG/SuperAG is a proprietary, non-standard technology, we cannot give any guarantees as to the ability of our product to capture, decode, and decrypt the packets being transmitted in SuperG/SuperAG mode. Understanding The Difference Between The Scanner Window And Nodes Tab While the Scanner window looks similar to the Nodes tab of the main application window, there are important distinctions between them. The Scanner is a convenient tool for a quick site survey and detection of access points and stations. It doesn't provide detailed per-node statistics and may include even non-wireless hosts (if the Hide wired hosts box is not checked), to give you a better understanding of the network topology. |
