Bettercap: Block ARP Spoofing

TL;DR

This guide shows you how to use Bettercap to detect and block ARP spoofing attacks on your network. We’ll focus on filtering malicious ARP packets to protect your devices.

Prerequisites

• Bettercap installed: Installation Guide
• Root or administrator privileges (needed for packet sniffing).
• Basic understanding of your network interface name (e.g., eth0, wlan0). You can find this using ifconfig on Linux/macOS or ipconfig /all on Windows (in PowerShell).

Steps

1. Start Bettercap

   Open a terminal and run Bettercap with root privileges, specifying your network interface:

   sudo bettercap -iface eth0

   (Replace eth0 with your actual interface name.)

2. Enable ARP Spoofing Detection

   Bettercap has built-in modules for detecting ARP spoofing. Enable the arp.spoof module:

   net.probe on

   This starts probing your network to identify devices and their MAC addresses.

3. View Detected Attacks

   Bettercap will automatically display any detected ARP spoofing attacks in the console. Look for entries with suspicious activity:

   arp.spoof

   This command shows all current ARP spoofing events.

4. Filter Malicious Packets

   To actively block the attacks, you can use Bettercap’s filtering capabilities. The most common approach is to block traffic based on MAC address:

   1. Identify the Attacker’s MAC Address: From the output of arp.spoof, note the MAC address of the attacker.
   2. Block the MAC Address: Use the net.block command to block all traffic from that MAC address:

      net.block mac 00:11:22:33:44:55

      (Replace 00:11:22:33:44:55 with the attacker’s MAC address.)

5. Advanced Filtering (IP Address)

   If you know the IP address of the attacker, you can block traffic based on that as well:

   net.block ip 192.168.1.100

   (Replace 192.168.1.100 with the attacker’s IP address.)

6. Using a Filter List

   For more complex scenarios, you can create and use filter lists:

   1. Create a Filter File: Create a text file (e.g., blocklist.txt) containing the MAC or IP addresses to block, one per line.
   2. Load the Filter List: Use the net.loadfilter command:

      net.loadfilter /path/to/blocklist.txt

7. Persistent Blocking (Optional)

   Bettercap’s blocking is active only while the tool is running. For persistent blocking, you’ll need to integrate Bettercap with other security tools or configure firewall rules based on the information gathered by Bettercap.

Important Considerations

• False Positives: Be careful when blocking MAC addresses. Blocking legitimate devices can disrupt network connectivity. Double-check before adding any address to your blocklist.
• Attacker Spoofing: Attackers can change their MAC address, so the block may not be effective indefinitely.
• cyber security Best Practices: ARP spoofing is just one type of attack. Implement other cyber security measures like strong passwords, regular software updates, and a firewall for comprehensive protection.