This class encapsulates a subnet-to-subnet NAT, which is usable in PFService only, and limited to SNAT. It requires a list of from, to, translated to, fwmark parameters:

The NAT policy could be only used as SNAT, the translated address is used to translate the source address of the connection. The translation occurs according to the first matching rule. The translation happens in POSTROUTING mangle chain. This NAT adds an extra 4 bit FWMARK to the traffic, additionally to the PNS MARK bits. This can be used for advanced routing by FWMARK.