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Dot11Sniffer

The 802.11 device counting script for CSCI379. This counts the number of active devices in an 802.11 network by using a network card in monitor mode.

Initial Configuration

To configure your computer, you must do three things: (1) install necessary prerequisite libraries (2) configure NetworkManager or your chosen Linux network management utility to ignore your wireless device, and (3) use Aircrack to enable monitor mode on your card.

Install Aircrack and Scapy

The prerequisite libraries are as follows:

  1. aircrack-ng
  2. scapy
  3. netifaces python library

To install aircrack-ng and scapy, run the following command on a debian-based Linux machine.

apt-get install aircrack-ng scapy

To install netifaces, you must use the python package manager. Make sure that you are installing the library for python2 and not python3!

pip install netifaces

Configure NetworkManager

To tell NetworkManager to ignore your wireless card, first find the device's MAC address. The ip addr program will tell you the mac address of your device. On my computer, the wireless device I use is called wlp0s20u2. Under that device, look for the string just to the right of the line that says "link/ether". It is a series of six hex number separated by colons.

Once you have your MAC address, modify /etc/NetworkManager/NetworkManager.conf. In this file, add the following. If there is already a [keyfile] section, add it to that section.

[keyfile]
unmanaged-devices=mac:$MAC_ADDR

Where $MAC_ADDR is your MAC address with colons between them. When added, make sure you restart NetworkManager. If you aren't sure how to do this, just restart your computer. When NetworkManager is brought back up and you plug your device in, NetworkManager should say "unmanaged" next to the device.

Use Aircrack

Once the device is no longer managed by NetworkManager, use the airmon-ng utility to bring up a monitor network interface. This is done by typing:

airmon-ng start $DEVICE $CHANNEL

Where $DEVICE is the name of your device and $CHANNEL is the wireless channel you wish to listen on. For our CSCI379 project, use channel 6. This application should create a virtual network device called mon0. When using scapy, make sure you listen to this device and not on the hardware device. This python script currently implicitly attempts to connect to the mon0 interface although this may change in the future.