The “v6” part just means that it’s specifically designed for IPv6 networks (which are becoming more and more common these days).
So basically, when your Kali Linux machine sends out an ICMPv6 packet, it’s like saying “hey there, neighbor! Can you confirm if this network path is still working?” And the receiving device responds with either a “yes” or “no”. This can be really helpful for troubleshooting connectivity issues and figuring out where things are going wrong in your network.
Now how to actually set up ICMPv6 on Kali Linux using IPTables (which is the firewall tool that comes pre-installed). First, you need to make sure that IP forwarding is enabled by running this command:
# This script enables IP forwarding and sets up ICMPv6 on Kali Linux using IPTables.
# First, we need to check if IP forwarding is enabled by editing the sysctl.conf file.
# The "echo" command adds the line "net.ipv4.ip_forward=1" to the end of the file.
echo "net.ipv4.ip_forward=1" >> /etc/sysctl.conf
# Next, we need to reload the sysctl.conf file to apply the changes.
# The "sysctl -p" command reads and processes the sysctl.conf file.
sysctl -p
This will add a line to the sysctl configuration file and then immediately apply those changes without rebooting (which is handy for testing purposes). Next, you’ll want to create some IPTables rules that allow ICMPv6 traffic through:
# This script adds IPTables rules to allow ICMPv6 traffic through.
# The following line adds a rule to the INPUT chain, allowing ICMPv6 echo requests.
sudo iptables -A INPUT -p icmpv6 --icmpv6-type echo-request -j ACCEPT
# The following line adds a rule to the OUTPUT chain, allowing ICMPv6 echo replies.
sudo iptables -A OUTPUT -p icmpv6 --icmpv6-type echo-reply -j ACCEPT
These commands add two new rules to the IPTables chain called “INPUT” and “OUTPUT”. The first rule allows incoming ICMPv6 packets with an “echo-request” type, while the second rule allows outgoing ICMPv6 packets with an “echo-reply” type. This is important because some routers may block these types of packets by default (which can cause problems for certain applications).
Finally, you’ll want to save your IPTables rules so that they persist across reboots:
#!/bin/bash # This line specifies the interpreter to be used for executing the script
# This script saves IPTables rules to persist across reboots
sudo iptables-save > /etc/iptables.rules # This line uses sudo to run the iptables-save command and redirects the output to the /etc/iptables.rules file
# The following lines add rules to the IPTables firewall
sudo iptables -A INPUT -p tcp --dport 22 -j ACCEPT # This line allows incoming TCP packets on port 22 (SSH)
sudo iptables -A INPUT -p tcp --dport 80 -j ACCEPT # This line allows incoming TCP packets on port 80 (HTTP)
sudo iptables -A INPUT -p tcp --dport 443 -j ACCEPT # This line allows incoming TCP packets on port 443 (HTTPS)
sudo iptables -A INPUT -p icmpv6 --icmpv6-type echo-request -j ACCEPT # This line allows incoming ICMPv6 packets with an "echo-request" type
sudo iptables -A OUTPUT -p icmpv6 --icmpv6-type echo-reply -j ACCEPT # This line allows outgoing ICMPv6 packets with an "echo-reply" type
# The following line saves the IPTables rules to the /etc/iptables.rules file
sudo iptables-save > /etc/iptables.rules
This will create a new file called “iptables.rules” in the “/etc/” directory, which contains all of your current IPTables rules (including any custom ones you’ve added). You can then use this script to automatically load those rules whenever Kali Linux starts up:
#!/bin/bash
# This script will load the iptables.rules file on startup
# Check if the iptables.rules file exists in the /etc/ directory
if [ -f /etc/iptables.rules ]; then
# If the file exists, print a message indicating it is being loaded
echo "Loading iptables.rules..."
# Use sudo to run the iptables-restore command and pass in the iptables.rules file as input
sudo iptables-restore < /etc/iptables.rules
fi
Save this script as a new file called “load_iptables.sh” in the “/usr/local/bin/” directory (which is where Kali Linux looks for custom scripts by default). Then, make it executable:
#!/bin/bash
# This is a bash script, indicated by the shebang at the top of the file
# Set the permissions of the script to be executable
chmod +x /usr/local/bin/load_iptables.sh
# Use sudo to run the following commands as a superuser
sudo iptables -F # Flush all existing rules in the iptables firewall
sudo iptables -X # Delete all existing user-defined chains
sudo iptables -t nat -F # Flush all existing rules in the nat table
sudo iptables -t nat -X # Delete all existing user-defined chains in the nat table
sudo iptables -t mangle -F # Flush all existing rules in the mangle table
sudo iptables -t mangle -X # Delete all existing user-defined chains in the mangle table
sudo iptables -P INPUT ACCEPT # Set the default policy for the INPUT chain to ACCEPT
sudo iptables -P FORWARD ACCEPT # Set the default policy for the FORWARD chain to ACCEPT
sudo iptables -P OUTPUT ACCEPT # Set the default policy for the OUTPUT chain to ACCEPT
# Save the current iptables rules to a file
sudo iptables-save > /etc/iptables/rules.v4
# Print a message to the user indicating that the iptables rules have been successfully loaded
echo "Iptables rules have been successfully loaded."
And finally, add a line to the “/etc/rc.local” file that calls this script whenever Kali Linux starts up (just before the “exit 0” line):
#!/bin/bash
# This is a bash script that will add a line to the "/etc/rc.local" file to call another script on Kali Linux startup.
# First, we need to use sudo to gain root privileges in order to edit the "/etc/rc.local" file.
sudo echo "source /usr/local/bin/load_iptables.sh" >> /etc/rc.local
# The ">>" operator appends the given text to the end of the specified file.
# The "source" command will execute the specified script within the current shell, rather than creating a new subshell.
# This is important because we want the changes made by the "load_iptables.sh" script to persist after it finishes executing.
# The "/usr/local/bin/load_iptables.sh" path is where the "load_iptables.sh" script is located.
# This script is responsible for loading custom iptables rules on system startup.
# Finally, we are adding this line to the "/etc/rc.local" file just before the "exit 0" line.
# This ensures that the "load_iptables.sh" script will be executed before the system fully boots up.
# Note: It is important to use the full path to the "load_iptables.sh" script in order for it to be executed properly on startup.
Now, when you reboot your machine or start a new terminal session, your IPTables rules will automatically be loaded and applied!