Network Address Translation (NAT) implementation in RipEX covers also the extended version: Network Address and Port Translation (NAPT). This is a technique in which port numbers and private Internet Protocol (IP) addresses are mapped from multiple internal hosts to one public IP address.
Source NAT (SNAT) changes the source address and/or port of the outgoing connection. The returning packets are also changed in the same way. Source NAT is performed on packets leaving the device. It takes place after routing and filtering in the firewall.
Destination NAT (DNAT) changes the destination address and/or port of the incoming connection. The returning packets are also changed in the same way. Destination NAT is performed on packets entering the device. It takes place before routing and filtering in the firewall.
Please see more details in RipEX Manual.