berlioz ~ # iptables -t nat -nvL POSTROUTING
Chain POSTROUTING (policy ACCEPT 84 packets, 7170 bytes)
 pkts bytes target     prot opt in     out     source               destination
   89  8752 nova-network-POSTROUTING  all  --  *      *       0.0.0.0/0            0.0.0.0/0
    5   289 MASQUERADE  all  --  *      enp2s0  0.0.0.0/0            0.0.0.0/0
 2908  203K nova-compute-POSTROUTING  all  --  *      *       0.0.0.0/0            0.0.0.0/0
 6748  458K nova-postrouting-bottom  all  --  *      *       0.0.0.0/0            0.0.0.0/0
    7  1127 MASQUERADE  all  --  *      *       172.17.0.0/16       !172.17.0.0/16