Hello,

We are porting MbedTLS 2.16 for FTP server. There are 2 connection in FTP communication, Control and data.

For control communication we are ok with handshake but data communication handshake is having issue. We have observed with FTP Client (FileZilla) our earlier implementation of FTP server with Mocana secure library, we used to send certificate and server key exchange in control communication handshake only, for Data communication handshake ServerHello and change cipher spec was sent. But in case of MbedTLS, we are sending certificate and server key exchange in data communication handshake also. FTP Client (FileZilla) is rejecting the handshake after receiving the server certificate server key exchange and from the FTP server as I believe it is expecting session resumption and FTP Server is waiting for client key exchange in handshake.

In attached wireshark trace, packet number 1570 is having issue.

When we tested this server with another FTP client (WinSCP), its working fine as this client is not expecting session resumption.

As I go through the code documentation of MbedTLS, I found that we cannot set the session resumption at server side, only client side we can do this setting. How can we make FTP server ready with session resumption? Please support us.

Thanks and Regards,

Sunil