Mailinglist Archive: opensuse (783 mails)

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Re: [opensuse] Fwd: Basically every WiFi device just hacked?
On 10/18/2017 01:07 PM, Wols Lists wrote:
Most sessions nowadays are spread-spectrum. I'm not sure how it works,
but if you disrupt the connection open sequence, ie get the client
transmitting on one frequency, and the router receiving on another, you
can MITM the conversation.

You're right, you don't know how it works. All current WiFi uses
something called Orthogonal Frequency Division Multiplexing (OFDM),
which has several carriers spread across the channel. All of the
carriers are modulated at the same time, with different parts of the
data. There is no switching from one frequency to another. Impairments
on one carrier simply means less or no data over that particular
carrier. The exception is 802.11b, which uses a different method called
Direct Sequence Spread Spectrum (DSSS), but that (hopefully) is not
still in use, as the encryption in 802.11b is really poor.

https://en.wikipedia.org/wiki/Orthogonal_frequency-division_multiplexing

Incidentally, O'Reilly has some good books on WiFi, that describe the
modulation methods used and much more.

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