scandump

A command-line utility that scans for Wi-Fi networks using the 802.11 netlink API and outputs the scan results in PCAP format.

Typically, processes that need to gather data about nearby Wi-Fi networks would do a scan using iw and scrape its text output. However, it is generally a bad idea to try parsing another program's output if it is not designed to be consumed by other processes. The text may change with newer updates or simply by running the program on a different system.

With scandump, no more scraping is needed. As an additional benefit, you can generate a PCAP file with radiotap + beacon frame data from the scan using a wireless interface that may not support monitor mode.

Installation

# Install pre-requisites
sudo apt update
sudo apt install git build-essential libnl-genl-3-dev libpcap-dev

# Download, build, and install scandump
git clone https://github.com/intuitibits/scandump.git
cd scandump
make
sudo make install

Usage

Usage: scandump [-c count] [-f frequency-list] [-p] [-h] [--version] <interface> <filename>
Options:
  -c, --count         Exit after the specified number of scans
  -f, --frequency     Comma-separated list of frequencies in MHz to scan
  -p, --passive       Use passive scan mode
  -h, --help          Display this help message
  --version           Show version

Where <interface> is the name of the WLAN interface (e.g. wlan0), and <filename> is the name of the PCAP file to be generated. Standard output is used if filename is -.

The command must be run as root since only privileged processes can initiate a scan.

Examples

Scan for Wi-Fi networks on wlan0 and save the scan results to scan.pcap:

$ sudo scandump wlan0 scan.pcap

Scan for Wi-Fi networks on wlan0 and output the scan results to standard output in PCAP format:

$ sudo scandump wlan0 -

Scan for Wi-Fi networks on wlan0 using channels 1 (2.4 GHz) and 36 (5 GHz) only:

$ sudo scandump -f 2412,5180 wlan0 scan.pcap

Scan for Wi-Fi networks on wlan0 passively (don't transmit probe requests):

$ sudo scandump --passive wlan0 scan.pcap