Monday, January 14, 2013

Capturing 802.11 Frames in Wireshark

Figured I would pass this along. I started reading chapter 15 in the CCNP Switch certification Guide; Integrating Wireless LANs. While reading the first few pages, I quickly wanted to get a sniffer out and check out all of these 802.11 frame specifications that it references.

Some examples are DIFS(duration timer) and the random back off timer.  I decided to fire up Wireshark, but the frames kept appearing as 802.3(Ethernet) frames. This is known as "fake" Ethernet headers. Unfortunately, with the current WIFI card installed in my laptop, I won’t be able to sniff  802.11 traffic.  

Per Wire Shark:
Without any interaction, capturing on WLAN's may capture only user datapackets with "fake" Ethernet headers. In this case, you won't see any 802.11 management or control packets at all, and the 802.11 packet headers are "translated" by the network driver to "fake" Ethernet packet headers.

http://wiki.wireshark.org/CaptureSetup/WLAN

You can also download a 802.11 capture and learn how to read it by following this document.

http://www.cse.ust.hk/~muppala/csit5610/labs/Wireshark_labs/Wireshark_802_11.pdf


 

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