We use the FTPS server functionality of a B2B application and to configure the FTPS for high availability, we have used a virtual IP.

i.e the actual services would be running on IP 10.12.45.45 9022 and the FTPS client will be connecting to the virtual IP 10.12.50.50 port 9022, which will then forward the communications to the actual IP.

We have also written an FTPS client using Apache Commons Net. The problem is that the client is able to establish a session with the server successfully only if there is a NAT mentioned on the server as 10.12.50.50 (Virtual IP). Else it terminates the connection.

The other FTPS clients available over the internet (like Moveitfreely) does connect successfully without NAT-ing.

Is there a way in Apache Commons net to make the connection without NAT-ing as we have a single point of failure on the load balancer?

Thank you.