config.gateway.json

{
   "service": {
      "nat": {
         "rule": {
            "1": {
               "description": "DNS Redirect",
               "destination": {
                  "address": "!192.168.1.1",
                  "port": "53"
               },
               "inbound-interface": "eth1",
               "inside-address": {
                  "address": "192.168.1.1"
               },
               "log": "disable",
               "protocol": "tcp_udp",
               "type": "destination"
            }
         }
      }
   }
}