common: Disable packet filter for all machines.

Enabling netfilter, especially connection tracking modules add
unnecessary complexity to the systems. So I really don't want to
increase the attack surface of the machine because of that.

Just close the ports you don't need and listen locally for stuff that
doesn't need to be public and we don't really need to have netfilter
enabled.

Signed-off-by: aszlig <aszlig@redmoonstudios.org>