ARP Spoofing: Troubleshooting Internet Connectivity Issues

If you’re planning to perform an ARP spoofing attack, you’ve probably encountered bettercap. If you’ve already set up a lab to experiment with ARP spoofing, you may have stumbled upon an issue where the internet is not reachable on your target. In this post, we’ll explore the root cause of this issue and provide a step-by-step guide to resolve it.

The problem

When performing an ARP spoofing attack, you may encounter connectivity issues on your target. This is because ARP spoofing works by intercepting and modifying ARP requests, which can cause the target to lose its connection to the internet.

Solution

The problem might rely on two different things:

1. You have not enabled the IP forwarding parameters
2. Your firewall is blocking the packet.

IP Forwarding

First, check if the IP forwarding is enabled.

cat /proc/sys/net/ipv4/ip_forward
# Output: 0 (disabled) or 1 (enabled)

If the output is 0, you will need to enable it. To do so, run one of the following commands:

# Method 1
echo 1 > /proc/sys/net/ipv4/ip_forward

# Method 2
sysctl -w net.ipv4.ip_forward=1

Note: Using this method, the change will be lost on reboot.

Firewall

It’s also possible that your firewall is blocking the packet. If you haven’t configured any firewall rules, accept forwarding packet:

sudo iptables -P FORWARD ACCEPT

Those parameters will be lost on reboot.

If you have custom rules on your firewall, think twice before flushing everything.

Using Bettercap to Manage the Issue

Another solution is to let bettercap manage this for you.

Please note that bettercap will not restore your previous parameters, especially for the firewall rules.

To solve this issue within bettercap, you need to start at least one of the available proxies, except for the HTTPS one. When launching the proxy, bettercap will configure everything.

* http.proxy on || dns.proxy on || any.proxy on || tcp.proxy on

Now, you have everything set up to successfully perform your ARP spoof.

This blog post is licensed under CC BY-SA 4.0