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https://github.com/geovation/wifispy

Sniff Wifi traffic, log device addresses.
https://github.com/geovation/wifispy

Last synced: 2 months ago
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Sniff Wifi traffic, log device addresses.

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README 

        
Wifi Spy

========



Sniff Wifi traffic, log device addresses.



Uses [Pcapy](https://github.com/CoreSecurity/pcapy) to capture packets. It's probably the best mantained out of [many](https://pypi.python.org/pypi?%3Aaction=search&term=pcap) libraries wrapping the somewhat definitive packet capture library [libpcap](https://github.com/the-tcpdump-group/libpcap).



Uses [Dpkt](https://github.com/kbandla/dpkt) to interrogate and extract data from each packet. It's one of two popular packet manipulation libraries, the other being [Impacket](https://github.com/CoreSecurity/impacket), which I had less luck with.



The other notable library in this space is [Scapy](https://github.com/secdev/scapy/).



Running

-------



There's two different sets of configuration for Mac OS and Linux in `wifispy.py`, you'll have to comment out the appropriate set before running. I've only been able to make it work on Linux so far.



    $ pip install -r requirements.txt

    $ sudo python wifispy.py



Needs to be run with `sudo` because we're doing system-level stuff. For the same reason `pcapy` won't work within a virtual environment.



Approach

--------



1. Put card into [monitor mode](https://en.wikipedia.org/wiki/Monitor_mode). This means it will passively sniff all wireless traffic it sees. It differs from the somewhat similar [promiscuous mode](https://en.wikipedia.org/wiki/Promiscuous_mode), which (as I understand it) gives you more information, but requires you to be connected to a network. Not all cards support monitor mode. This is done via a terminal command, as it doesn't seem possible through Python.



2. Rotate channels. There are 13 channels in the 2.4GHz band, which are the most commonly used. There are also a number of others in the 5GHz range, but not all cards support these channels. Since cards can only be tuned to one channel at a time, we need to randomly switch channels in the background to ensure we're picking up devices using any channel. This is also done via a terminal command. Note that the nature of this process means we will miss some (many) packets, but for our purposes that shouldn't be a problem.



3. Sniff packets using Pcapy. Each packet recieved goes into a function for processing.



4. Process sniffed packets using Dpkt. Each first needs to be decoded. Using a [Radiotap](http://www.radiotap.org/defined-fields) decoder means we can access 'pseudo-headers' which are inserted by the card rather than having actually been transmitted. Radiotap is a standard for injecting/interpreting these, though what actual information ends up there is up to the card manufacturer. For example, one card I tested packets did not include any signal strength data.



5. There are three types of wireless (aka. 802.11) packet: management, control, and data. Each differs in what information it contains. Extract the key fields from the Radiotap headers, and write these along with the current timestamp to an in-memory queue.



6. In the background, periodically write everything from the queue to a SQLite database.



Unanswered questions

--------------------



* Very occassionally the error `Key error: 1 10` gets printed to the console. I don't know why.

* The logs show periodic exceptions (`Key error: 127`) from trying to parse some packets. This seems to happen more often when the card is tuned to channel 6, from what I can see. I suspect the source is some device broadcasting malformed packets on this channel, but I've not been able to confirm this.

* I've derived a number for signal (in dBm), but it does not take into account how much noise there is, although that's probably relevant too.

* I've not got this to work on OS X -- BSD-based systems use the `/dev/bpf*` devices, which Pcapy doesn't seem to be able to cope with. It doesn't look like Scapy supports it either, but it does seem to [be being worked on](https://github.com/secdev/scapy/issues/104).



Related projects

----------------



* [wifi-monitor](https://github.com/dave5623/wifi_monitor)

* [wifi-rifle](https://github.com/sensepost/WiFi-Rifle)



Articles

--------



* https://www.crc.id.au/tracking-people-via-wifi-even-when-not-connected/

* http://edwardkeeble.com/2014/02/passive-wifi-tracking/



On the command-line

-------------------



This is a list of commands I've found useful whilst working on this project.



### Mac



You will need to use the `airport` command, so create a symlink:



    $ sudo ln -s /System/Library/PrivateFrameworks/Apple80211.framework/Versions/Current/Resources/airport /usr/local/bin/airport



Find out the names of your network interfaces:



    $ ifconfig



The default Wifi interface appears to be named `en0`.



Select the channel you would like to sniff (here, channel 6):



    $ airport en0 channel 6



See all the existing networks and their channels:



    $ airport en0 scan



Put your card into monitor mode:



    $ sudo tcpdump -i en0 -Ic1 -py IEEE802_11



If this has worked it will say so in `airport en0 getinfo`.



To take the card out of monitor mode:



    $ sudo tcpdump -i en0 -Ic1



Sniff traffic and store in a `pcap` file:



    $ sudo tcpdump -i en0 -I -pw output.pcap



### Linux



Check what country the system thinks you're in. This will affect what channels you can use.



    $ iw reg get



It should say `country GB`, but if not:



    $ iw reg set GB



This will mean you get all possible UK frequencies when you:



    $ iwlist wlan1 freq



Find out the names of your network interfaces:



    $ ifconfig



The default Wifi interface appears to be named `wlan1`.



Select the channel you would like to sniff (here, channel 6):



    $ iw dev wlan1 set channel 6



See all the existing networks and their channels:



    $ sudo iwlist wlan1 scan



Put your card into monitor mode:



    $ iw dev wlan1 set type monitor



If this has worked it will say so in `iwconfig`.



To take the card out of monitor mode:



    $ iw dev wlan1 set type managed



Sniff traffic and store in a `pcap` file:



    $ sudo tcpdump -i en0 -I -pw output.pcap