How to disable IPv6 on Debian/Kali Linux

TL;DR

git clone https://github.com/romankurnovskii/kali-shortcuts.git
cd kali-shortcuts
chmod +x disable_ipv6.sh
sudo ./disable_ipv6.sh

Edit sysctl Configuration

• In the terminal, type sudo vi /etc/sysctl.conf and press Enter. This opens the sysctl.conf file in the text editor with root privileges.

Add IPv6 Disable Lines

• At the end of the file, add the following lines:

net.ipv6.conf.all.disable_ipv6 = 1
net.ipv6.conf.default.disable_ipv6 = 1
net.ipv6.conf.lo.disable_ipv6 = 1

These lines will disable IPv6 on all network interfaces, including the loopback interface.

Save and Exit

• Save /etc/sysctl.conf and exit text editor

Apply Changes

• To apply the changes without rebooting, run `sudo sysctl -p`` in the terminal. This will reload the sysctl configuration with your changes.

Verify Changes (Optional)

To confirm that IPv6 is disabled, you can run `cat /proc/sys/net/ipv6/conf/all/disable_ipv6``. If it returns 1, then IPv6 has been successfully disabled.

Reboot (Optional)

While the sysctl -p command applies changes immediately, it’s a good idea to reboot your system to ensure that the changes persist after a restart. You can reboot by typing sudo reboot in the terminal.

Troubleshooting

Linux can’t add IPv6 to interface tun0

Can happen when trying to connect through OpenVPN.

In the client file .ovpn add lines:

pull-filter ignore "ifconfig-ipv6"
pull-filter ignore "route-ipv6"