NAT logging with netflow9

By the way, here is example of the netflowjs output from mikrotik version9 flow:

{ header:
   { version: 9,
     count: 20,
     uptime: 387036340,
     seconds: 1448913629,
     sequence: 50976101,
     sourceId: 0 },
  flows:
   [ { last_switched: 387021220,
       first_switched: 387021220,
       in_pkts: 3,
       in_bytes: 156,
       input_snmp: 19,
       output_snmp: 18,
       ipv4_src_addr: '46.33.68.47',
       ipv4_dst_addr: '7.777.176.64',
       protocol: 6,
       src_tos: 0,
       l4_src_port: 80,
       l4_dst_port: 18477,
       ipv4_next_hop: '192.168.9.10',
       dst_mask: 0,
       src_mask: 0,
       tcp_flags: 17,
       in_dst_mac: '4c5e0c242dc5',
       out_src_mac: '4c5e0c242dc3',
       postNATSourceIPv4Address: '46.33.68.47',
       postNATDestinationIPv4Address: '172.16.26.78',
       postNAPTSourceTransportPort: 80,
       postNAPTDestinationTransportPort: 18477,
       fsId: 256 },
     { ...