Prevent IPv6 leak with some VPN providers
In order to prevent IPv6 with some VPN providers, you have to disable this functionality for a specific interface.
Check here if you have some leakage (after connected to a VPN).
sudo sysctl -w net.ipv6.conf.tun0.disable_ipv6=1
vim /etc/sysctl.conf net.ipv6.conf.tun0.disable_ipv6 = 1