ffdo-ansible/roles/gateway-nat/templates/nat-address.cfg.j2

auto nat0
iface nat0 inet static
    address {{ nat_ipv4|ipaddr('address') }}
    netmask 255.255.255.255
    pre-up ip link add $IFACE type dummy
    pre-up ip link set up dev $IFACE
    pre-up ip rule add from {{ nat_ipv4 }} table 42
    pre-up ip rule add to {{ nat_ipv4 }} table 42
    post-down ip rule del from {{ nat_ipv4 }} table 42
    post-down ip rule del to {{ nat_ipv4 }} table 42
    post-down ip link set down dev $IFACE
    post-down ip link del dev $IFACE