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Here's my setup:

1) MacBook Pro in monitor mode with Wireshark installed. 2) A WiFi router connected to the internet 3) An iPhone, connected to the WiFi router via WPA2

I start a streaming video on the iPhone so there's data moving to the iPhone from the WiFi router.

I fire up Wireshark on the MacBook Pro.

I wrap the iPhone in aluminum foil and place it in a metal filing cabinet. I wait several seconds, take it out, unwrap the foil from the phone, wait a few seconds and then stop the Wireshark recording.

Now, what I need to do with the data is figure out how bad the signal got through the ordeal. I know while the phone was in the cabinet, it stopped communicating with the router, as there's an obvious gap in the timestamps for the packet flow. But I'd like a little bit more detail. I'd like the packet error rate as well. Can Wireshark supply this information through one of the Statistics windows and I'm just not seeing it?

asked 24 May '17, 15:12

briank's gravatar image

briank
6112
accept rate: 0%


This is an interesting test, and Wireshark can likely provide at least some more information. A couple of ideas:

1.

You could evaluate changes in signal strength (RSSI) as you manipulate the DuT (device under test). Have a look at the SSI signal field in the Radiotap header from the frames transmitted by the DuT. You could use a filter such as

wlan.ta == (mac address of DuT)

and then review the radiotap header:

Radiotap Header v0, Length 20
    Header revision: 0
    Header pad: 0
    Header length: 20
    Present flags
    Flags: 0x10
    Data Rate: 12.0 Mb/s
    Channel frequency: 2412 [BG 1]
    Channel flags: 0x00c0, Orthogonal Frequency-Division Multiplexing (OFDM), 2 GHz spectrum
    **SSI Signal: -57 dBm**
    SSI Noise: -100 dBm
    Signal Quality: 75
    Antenna: 0
    SSI Signal: 43 dB

In this case, focus on SSI Signal, and how it changes as you manipulate the device. You can add this as a column in the packet view, or even graph it (graph in the Qt version as the GTK version does not handle negative numbers gracefully).

2.

Evaluate retries - as communication degrades, the number of retries will likely increase. I would graph this, and we could do something like this filter:

wlan.addr == (mac address of DuT) and wlan.fc.retry == 1

While conditions are poor, there should be more retries.

3.

Evaluate Datarate - as communication degrades, datarate often does as well. You could graph min/max/avg datarates to/from the DuT. Something like this field name for the Y field in the graph tool, and then do a Display filter for the DuT. An example set of config items:

Y field: wlan_radio.data_rate
Display Filter:  wlan.ta == (mac address of DuT)
Y Axis: AVG(Y field)

4.

Evaluate bad frames - as communication degrades, perhaps the number of bad frames does as well. Check for FCS field and see if the number of bad frames increases to/from the DuT while communication is impaired.

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answered 26 May '17, 04:07

Bob%20Jones's gravatar image

Bob Jones
1.0k2515
accept rate: 21%

edited 26 May '17, 04:09

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question asked: 24 May '17, 15:12

question was seen: 1,274 times

last updated: 26 May '17, 04:09

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