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Posts Tagged ‘Remote Packet Capture’

Packet Capture with AP Radios – What’s Under the Hood?

May 19th, 2014

Wireless packet capture has always been important to Wi-Fi professionals and support engineers for resolving network problems. With the diversity of wireless clients that is already around and which is only expected to grow with the Internet of Things (IoT), packet capture capabilities will continue to be critical. Wireless packet capture can be facilitated in the AP radios using the hardware and the driver level hooks. Read on to find out what’s under the hood.

There are two main plumbing points to get frames from wireless up to the application: one in the hardware and the other in the driver software. At the hardware level, the radio supports “Promiscuous Mode” option. When this option is activated, the hardware passes all wireless frames received on the channel where the radio is operating up towards the driver software. When this option is deactivated, the hardware passes only the wireless frames for the MAC of the radio (and the frames like probe requests & beacons based on the additional sub-settings under non-Promiscuous mode) up towards the driver software.

The driver software can operate in AP, STA, or Monitor Mode. 

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WLAN Troubleshooting

Wi-Fi Packet Capture Made Easy

May 8th, 2010

Recently, there have been multiple instances of Wi-Fi issues related to iPads. Apple has also acknowledged some of the issues - e.g.,an iPad may not automatically rejoin a known Wi-Fi network on a dual band router . Also, Princeton university has faced serious network problems due to iPad. This has been attributed to a problem in the DHCP client on iPad. Here is an interesting theory on how the IEEE 802.11 Power Save mode may be playing a role in this. The Wall Street Journal reports that such issues have lead to the ban of iPads at several universities. This is a cause for concern.  Read more…

Wireless security , ,