setIptablesForwardPolicy() makes default FORWARD policy accept

[donbowman]

Several issues:

a) ignores ip6tables
b) this silently breaks the firewall of the host its on

My host has iptables -P FORWARD drop, after I run kube-spawn, without knowing, I'm circumvented.

I think this needs to qualify by e.g. docker0 or cni0 interface.