$conf: HASH, contains the configuration to write $action: Str, possible values are "keep" or "drop"
0: requires user interaction 1: everything has been done
This function stores the configuration for shorewall inside the proper files.
if write_ is called without the $action parameter it can return 0 (i.e. user interaction requested) when the firewall configuration has been manually changed.
In that case the developer will have to handle this request by providing two choices within the domain (keep | drop) and then recall write_ with the choosen behaviour.