Comment 9 for bug 1595098

You can use the following commands to disable internet connectivity:
iptables -A OUTPUT -d 10.0.0.0/8 -j ACCEPT
iptables -A OUTPUT -d 192.168.0.0/16 -j ACCEPT
iptables -A OUTPUT -d 172.16.0.0/12 -j ACCEPT
iptables -A OUTPUT -j DROP