We have a Strongswan VPN server on Ubuntu 20.04 in AWS. It is used to establish a site-to-site VPN tunnel with a client.
Our VPN server will terminate VPN and NAT traffic to the RDS database server. In order for it to response correctly our VPN server will SNAT the packet with its address, so we basically lost track of the client computer's IP address. And there are multiple client computers.
In this case, how do we properly NAT the response to client?
Thank you for your time.