[ -z "$target" ] && target=DROP
[ -n "$src" ] && ZONE=zone_$src || ZONE=INPUT
[ -n "$dest" ] && TARGET=zone_${dest}_$target || TARGET=$target
[ -z "$target" ] && target=DROP
[ -n "$src" ] && ZONE=zone_$src || ZONE=INPUT
[ -n "$dest" ] && TARGET=zone_${dest}_$target || TARGET=$target