Ubuntu 16.04 learned new tricks to sneak in IPv6 which might be unwanted at certain times

ipv6off.sh

+#!/bin/sh
+sysctl -a net.ipv6.conf 2>/dev/null | awk '/disable_ipv6/ { print $1"=1"}' | xargs sysctl

ipv6on.sh

+#!/bin/sh
+sysctl -a net.ipv6.conf 2>/dev/null | awk '/disable_ipv6/ { print $1"=0"}' | xargs sysctl