besside-ng: Fix Bad Beacon Error

TL;DR

The “bad beacon error” in besside-ng usually means your wireless interface isn’t capturing beacons correctly. This guide shows how to fix it, covering common causes like monitor mode issues, incorrect channel settings, and driver problems.

Fixing the Bad Beacon Error

1. Check Monitor Mode
   • Make sure your wireless interface is in monitor mode. Use airodump-ng to verify.

     sudo airodump-ng wlan0mon

   • If it’s not in monitor mode, bring it down and up again:

     sudo ifconfig wlan0 down

     sudo iwconfig wlan0 mode monitor

     sudo ifconfig wlan0 up

2. Verify Channel
   • besside-ng needs to listen on the correct channel. Use airodump-ng to find the target network’s channel.

     sudo airodump-ng wlan0mon

   • Start besside-ng specifying the correct channel using the --channel option:

     sudo besside-ng -i wlan0mon --channel <channel_number>

3. Driver Issues
   • Some wireless drivers don’t handle monitor mode well. Try a different driver if possible.

     Check your distribution’s documentation for how to change drivers.

   • Update your kernel and firmware. Outdated software can cause compatibility problems:
     • Debian/Ubuntu:

       sudo apt update && sudo apt upgrade

     • Arch Linux:

       sudo pacman -Syu

4. Check for Interference
   • Radio interference can corrupt beacon frames. Move to a quieter location or try using a different wireless interface.
5. Increase Capture Time (if needed)
   • Sometimes, besside-ng doesn’t capture enough beacons initially. Let it run for a longer period:

     sudo besside-ng -i wlan0mon --channel <channel_number> -w captures

     Monitor the output and see if it eventually starts working.

6. Check for Virtual Interfaces
   • Ensure there aren’t conflicting virtual interfaces. Sometimes, other tools can create them that interfere with besside-ng.

     iwconfig

     If you find any unexpected interfaces, bring them down.

7. Restart Network Manager
   • Occasionally, network manager can interfere. Restarting it might help:

     sudo systemctl restart NetworkManager

cyber security Note

Always ensure you have permission before attempting to deauthenticate networks. Unauthorized access is illegal and unethical.