Blog | G5 Cyber Security

Fix Deauth Attacks

G5 Cyber Security

TL;DR

Deauthentication attacks aren’t working? This guide covers common causes and fixes for broadcast deauth requests failing, including monitor mode issues, channel hopping, driver problems, and regulatory restrictions. We’ll focus on practical steps using tools like aircrack-ng.

Troubleshooting Deauth Attacks

  1. Check Monitor Mode
    • Ensure your wireless interface is in monitor mode. This is essential for passively listening to and injecting packets.
    • Use iwconfig or airmon-ng check kill to verify.
  2. Verify Interface Name
    • Double-check the name of your wireless interface (e.g., wlan0, wlp3s0). Incorrect interface names are a common mistake.
    • Use iwconfig to list available interfaces.
  3. Start Monitor Mode Properly

    The correct way to start monitor mode is crucial.

    • First, stop any processes that might interfere: 
      sudo airmon-ng check kill
    • Then, bring down the interface: 
      sudo ifconfig wlan0 down
    • Start monitor mode: 
      sudo airmon-ng start wlan0
  4. Channel Hopping
    • Deauth attacks often fail if the target access point (AP) is channel hopping. This means it switches channels frequently.
    • Use airodump-ng to identify the AP’s current channel and hop pattern: 
      sudo airodump-ng wlan0mon
    • Continuously update your attack target based on the changing channel. You can do this manually or use tools that automate channel hopping.
  5. Driver Issues
    • Outdated or incompatible wireless drivers can cause problems with packet injection.
    • Update your drivers using your distribution's package manager (e.g., apt update && apt upgrade on Debian/Ubuntu).
    • Consider trying a different driver if available.
  6. Regulatory Restrictions
    • Some countries have regulations that limit the channels and power levels allowed for wireless devices.
    • Check your local regulations to ensure you're operating within legal limits.
    • You might need to adjust your configuration file (e.g., /etc/wireless/regdb) if necessary, but be aware of the legal implications.
  7. Correct Deauth Command Syntax
    • Ensure you're using the correct syntax for the deauth command in aircrack-ng: 
      sudo aireplay-ng --deauth 0 -a  -h  wlan0mon
      • Replace <BSSID> with the AP's MAC address.
      • Replace <MAC_ADDRESS> with the target client’s MAC address (or use FF:FF:FF:FF:FF:FF for a broadcast attack).
  8. Check for Interference
    • Other wireless devices or sources of electromagnetic interference can disrupt your attacks.
    • Try moving to a different location or reducing the number of nearby wireless devices.
  9. Power Levels and Range
    • Ensure your wireless adapter has sufficient power output for the range you're attempting to cover.
    • Some adapters have limited transmit power, which can affect their ability to send deauth packets effectively.
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