Disable IPv6 in Ubuntu 14.04 or 16.04

If you’d like to disable IPv6 for whatever reason on Ubuntu 14.04 or 16.04, give this one-liner a go:

sudo /bin/su -c "echo -e '\nnet.ipv6.conf.all.disable_ipv6 = 1\nnet.ipv6.conf.default.disable_ipv6 = 1\nnet.ipv6.conf.lo.disable_ipv6 = 1' >> /etc/sysctl.conf" && sudo sysctl -p && cat /proc/sys/net/ipv6/conf/all/disable_ipv6

It will echo three lines to the end of /etc/sysctl.conf, reload sysctl, and then cat the file /proc/sys/net/ipv6/conf/all/disable_ipv6 to let you know if IPv6 has been disabled (1) or not (0).