Blog | G5 Cyber Security

Fix Arpspoof Reply Speed

G5 Cyber Security

TL;DR

Arpspoof can be slow to respond to ARP requests when actively poisoning a network, causing connectivity issues. This guide shows how to reduce the reply delay by adjusting the timing parameters used by arpspoof.

Fixing Arpspoof Reply Speed

  1. Understand the Problem: Arpspoof works by sending fake ARP replies to redirect traffic. By default, it doesn’t send these replies *constantly*. It waits a bit between them. This delay can make connections seem unstable or slow because devices aren’t always getting the correct MAC address information quickly enough.
  2. Identify Your Arpspoof Command: The exact command you use will affect how you adjust the timing. Common examples include:
    • arpspoof -i -t (basic)
    • arpspoof -i -t -r (with repeat count)
  3. Reduce the Reply Interval: The key is to make arpspoof send replies more frequently. Unfortunately, standard `arpspoof` doesn’t have a direct option for this. We’ll use a loop and `arping` instead.
  4. Use a Loop with Arping (Recommended): This method sends ARP requests repeatedly to maintain the poisoning effect. It gives you much finer control over the reply rate than standard arpspoof. 
    while true; do arping -i  -s  ; sleep 0.1; done
    • Replace with your network interface (e.g., eth0, wlan0).
    • Replace with the IP address of the target you’re poisoning.
    • The sleep 0.1 command pauses for 0.1 seconds between each ARP request. Adjust this value (e.g., to 0.05 for faster replies, or 0.2 for slower) based on your network stability.
  5. Alternative: Using `dsniff`’s `arpflood` (If Available): If you have dsniff installed, the `arpflood` tool is designed to flood ARP requests and replies. 
    arpflood -i  -d
    • Replace with your network interface.
    • Replace with the target’s IP address. Be cautious; this can generate a lot of network traffic.
  6. Stop Arpspoof: If you were using the original `arpspoof` command, make sure to stop it before running the loop or `arpflood`. You can usually do this with Ctrl+C in the terminal where arpspoof is running.
  7. Test Connectivity: After implementing one of these solutions, test connectivity to and from the target. Check if connections are more stable and faster.
  8. Monitor Network Traffic (Important): Flooding ARP requests can be disruptive. Use tools like Wireshark or tcpdump to monitor network traffic and ensure you’re not causing excessive congestion or alerting intrusion detection systems. 
    tcpdump -i  arp
  9. Consider Ethical Implications: Remember that ARP spoofing is a cyber security technique often used in man-in-the-middle attacks. Only use it on networks you have permission to test, and for legitimate purposes (e.g., penetration testing).
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