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To capture wireless frames, we used three network sniffers, each
comprising a PC running Linux with the 2.4.19 kernel. Each sniffer
had a Prism2 chipset-based wireless network interface card; two
sniffers had Demarctech DT-RWZ0-200mW-WC cards,
and the third had a Linksys WPC11v3 card.
To measure traffic, we used the Ethereal protocol analyzer
(version 0.9.6) with the libpcap library (version 0.7).
Each card was placed into `monitor mode', which allowed the card
to capture 802.11 frame information on a target channel.
The sniffers captured the first 256 bytes of each
observed 802.11 frame, recording the complete view of the frame,
i.e., PHY/MAC/LLC/IP/Above-IP information.
PHY information, such as MAC Time and SNR (signal-to-noise ratio),
can be captured using Prism2 monitor header, which is not a
part of the IEEE 802.11 frame header, but is generated
by the firmware of the receiving card.