
The CONFIG_IP_NF_TARGET_NETMAP provides a target for the nat table. It creates
a static 1:1 mapping of the network address, while keeping host addresses
intact. It can be applied to the PREROUTING chain to alter the destination of
incoming connections, to the POSTROUTING chain to alter the source of outgoing
connections, or both (with separate rules).

Examples:

iptables -t nat -A PREROUTING -d 1.2.3.0/24 -j NETMAP --to 5.6.7.0/24

iptables -t nat -A POSTROUTING -s 5.6.7.0/24 -j NETMAP --to 1.2.3.0/24

