Controlled by BALENA_HOST_FIREWALL_MODE, the firewall can
either be 'on' or 'off'.
- In the 'off' state, all traffic is allowed.
- In the 'on' state, only traffic for the core services provided
by Balena is allowed.
Change-type: patch
Signed-off-by: Rich Bayliss <rich@balena.io>
