UGR/Experiment2

Wireless Capture

Stringing together the pieces:

Here is the single-step, high level version of what we are doing. This is essentially one single step in the data pipeline.

• Sensor hardware: Raspberry Pi that can run a boot script to collect data

To get more specific:

• Be able to power on the Raspberry Pi
• Be able to remotely connect to the Raspberry Pi via SSH
• Be able to control a wireless card from the Raspberry Pi via command line
• Be able to start and stop a wireless card using Python
• Be able to start and stop airodump process using Python

Putting all the pieces together, here is how the process will look:

• Plug a wireless card into the Pi (no power)
• Plug the Pi into power
• Boot script activates Python script
• Python script identifies onboard hardware
• Python script begins running airdoump at 1 minute intervals
• (optional) Python script connects to remote command-and-control server.
• (optional) stunnel trickiness

Implementation

Passwordless Login Raspberry Pi

Set up passwordless login following http://charlesreid1.com/wiki/SSH#Passwordless_Login

Then define the following alias in your .bashrc or wherever:

alias pi="pi"
function pi() {
  ssh-agent > ~/ssh.file # env vars in ssh.file 
  chmod +x ~/ssh.file # execute file
  ~/ssh.file > /dev/null
  rm -f ~/ssh.file
  export IP="10.0.0.4"
  ssh -Y root@${IP} # the actual ssh call
}

Now you can connect to the pi by typing:

$ pi

Test Startup Service

Create a test startup service by doing the following.

Create a custom startup script in /etc/init.d/custom-script with the following contents:

root@kali:/etc/init.d# cat custom-script 
#! /bin/sh

### BEGIN INIT INFO
# Provides:		custom-script
# Required-Start:	$local_fs $remote_fs
# Required-Stop:	$local_fs $remote_fs
# Default-Start:	2 3 4 5
# Default-Stop:		0 1 6
# Short-Description:	Here ya go buddy, custom script
### END INIT INFO

set -e

touch /root/ohai

exit 0

Make sure this is linked in the proper rcN.d/ folders by running update-rc.d custom-script defaults.

Now make sure there's no file rm /root/ohai and then run reboot. Once you reboot, you should see a file named ohai in the root directory.

Real Startup Service

Create a real startup service that will start capturing wifi data on boot. Assume wifi card is wlan0.

import subprocess
import time
from datetime import datetime

# each experiment will be Nhours in duration
Nhours = 2

# each CSV file will be Nseconds in duration
Nseconds = 15
 
# figure out how many files there will be 
Nfiles = (Nhours*3600)/Nseconds

# create a unique file prefix for this experiment
prefix = datetime.now().strftime('%Y-%m-%d_%H-%m')

for i in range(Nfiles):

    # construct the airodump command
    the_cmd = ['airodump-ng','wlan0','-w',prefix,'--output-format','csv']
 
    # call it
    p = subprocess.Popen(the_cmd)
 
    # wait for it
    time.sleep(Nseconds)

    # aaaaand bail 
    p.kill()
 
print "Success!"