Help! FTPS server connection drops

[jakelester66]

Issue: Cannot connect to FTPS server.

Context:
- able to log in, and authenticate credentials.
- server forcibly disconnects immediately after.
- connection is passive.

Help would be greatly appreciated!

Logs:
- see attachment below.
- Verbosity = 4 (debug)

filezilla.log

(11.13 KiB) Downloaded 34 times

[jakelester66]

LOGS (for anyone too cautious to download a random file from the internet ):

2022-07-27 15:05:39 23028 1 Trace: CControlSocket::SendNextCommand()
2022-07-27 15:05:39 23028 1 Trace: CFtpLogonOpData::Send() in state 0
2022-07-27 15:05:39 23028 1 Status: Resolving address of ftps.dojo.co
2022-07-27 15:05:39 23028 1 Status: Connecting to 3.228.61.22:21...
2022-07-27 15:05:39 23028 1 Status: Connection established, waiting for welcome message...
2022-07-27 15:05:39 23028 1 Trace: CFtpControlSocket::OnReceive()
2022-07-27 15:05:39 23028 1 Response: 220 Service ready for new user.
2022-07-27 15:05:39 23028 1 Trace: CFtpLogonOpData::ParseResponse() in state 1
2022-07-27 15:05:39 23028 1 Trace: CControlSocket::SendNextCommand()
2022-07-27 15:05:39 23028 1 Trace: CFtpLogonOpData::Send() in state 2
2022-07-27 15:05:39 23028 1 Command: AUTH TLS
2022-07-27 15:05:39 23028 1 Trace: CFtpControlSocket::OnReceive()
2022-07-27 15:05:39 23028 1 Response: 234 Command AUTH okay; starting TLS connection.
2022-07-27 15:05:39 23028 1 Trace: CFtpLogonOpData::ParseResponse() in state 2
2022-07-27 15:05:39 23028 1 Status: Initializing TLS...
2022-07-27 15:05:39 23028 1 Trace: tls_layer_impl::client_handshake()
2022-07-27 15:05:39 23028 1 Trace: tls_layer_impl::continue_handshake()
2022-07-27 15:05:39 23028 1 Trace: TLS handshakep: About to send CLIENT HELLO
2022-07-27 15:05:39 23028 1 Trace: TLS handshakep: Sent CLIENT HELLO
2022-07-27 15:05:39 23028 1 Trace: tls_layer_impl::on_send()
2022-07-27 15:05:39 23028 1 Trace: tls_layer_impl::continue_handshake()
2022-07-27 15:05:39 23028 1 Trace: tls_layer_impl::on_read()
2022-07-27 15:05:39 23028 1 Trace: tls_layer_impl::continue_handshake()
2022-07-27 15:05:39 23028 1 Trace: tls_layer_impl::on_read()
2022-07-27 15:05:39 23028 1 Trace: tls_layer_impl::continue_handshake()
2022-07-27 15:05:39 23028 1 Trace: tls_layer_impl::on_read()
2022-07-27 15:05:39 23028 1 Trace: tls_layer_impl::continue_handshake()
2022-07-27 15:05:39 23028 1 Trace: TLS handshakep: Received SERVER HELLO
2022-07-27 15:05:39 23028 1 Trace: TLS handshakep: Processed SERVER HELLO
2022-07-27 15:05:39 23028 1 Trace: TLS handshakep: Received CERTIFICATE
2022-07-27 15:05:39 23028 1 Trace: TLS handshakep: Processed CERTIFICATE
2022-07-27 15:05:39 23028 1 Trace: TLS handshakep: Received SERVER KEY EXCHANGE
2022-07-27 15:05:39 23028 1 Trace: TLS handshakep: Processed SERVER KEY EXCHANGE
2022-07-27 15:05:39 23028 1 Trace: TLS handshakep: Received SERVER HELLO DONE
2022-07-27 15:05:39 23028 1 Trace: TLS handshakep: Processed SERVER HELLO DONE
2022-07-27 15:05:39 23028 1 Trace: TLS handshakep: About to send CLIENT KEY EXCHANGE
2022-07-27 15:05:39 23028 1 Trace: TLS handshakep: Sent CLIENT KEY EXCHANGE
2022-07-27 15:05:39 23028 1 Trace: TLS handshakep: About to send FINISHED
2022-07-27 15:05:39 23028 1 Trace: TLS handshakep: Sent FINISHED
2022-07-27 15:05:40 23028 1 Trace: tls_layer_impl::on_read()
2022-07-27 15:05:40 23028 1 Trace: tls_layer_impl::continue_handshake()
2022-07-27 15:05:40 23028 1 Trace: TLS handshakep: Received NEW SESSION TICKET
2022-07-27 15:05:40 23028 1 Trace: TLS handshakep: Processed NEW SESSION TICKET
2022-07-27 15:05:40 23028 1 Trace: tls_layer_impl::on_read()
2022-07-27 15:05:40 23028 1 Trace: tls_layer_impl::continue_handshake()
2022-07-27 15:05:40 23028 1 Trace: TLS handshakep: Received FINISHED
2022-07-27 15:05:40 23028 1 Trace: TLS handshakep: Processed FINISHED
2022-07-27 15:05:40 23028 1 Trace: TLS Handshake successful
2022-07-27 15:05:40 23028 1 Trace: Protocol: TLS1.2, Key exchange: ECDHE-SECP384R1-RSA-SHA384, Cipher: AES-128-GCM, MAC: AEAD, ALPN:
2022-07-27 15:05:40 23028 1 Trace: tls_layer_impl::verify_certificate()
2022-07-27 15:05:40 23028 1 Trace: System trust store decision: true
2022-07-27 15:05:40 23028 1 Trace: Sending certificate_verification_event
2022-07-27 15:05:40 23028 1 Trace: CFtpControlSocket::SetAsyncRequestReply
2022-07-27 15:05:40 23028 1 Trace: set_verification_result(true)
2022-07-27 15:05:40 23028 1 Status: TLS connection established.
2022-07-27 15:05:40 23028 1 Trace: CControlSocket::SendNextCommand()
2022-07-27 15:05:40 23028 1 Trace: CFtpLogonOpData::Send() in state 6
2022-07-27 15:05:40 23028 1 Command: USER jake
2022-07-27 15:05:40 23028 1 Trace: CFtpControlSocket::OnReceive()
2022-07-27 15:05:40 23028 1 Trace: tls_layer_impl::on_read()
2022-07-27 15:05:40 23028 1 Trace: CFtpControlSocket::OnReceive()
2022-07-27 15:05:40 23028 1 Response: 331 User name okay, need password for jake.
2022-07-27 15:05:40 23028 1 Trace: CFtpLogonOpData::ParseResponse() in state 6
2022-07-27 15:05:40 23028 1 Trace: CControlSocket::SendNextCommand()
2022-07-27 15:05:40 23028 1 Trace: CFtpLogonOpData::Send() in state 6
2022-07-27 15:05:40 23028 1 Command: PASS *************
2022-07-27 15:05:41 23028 1 Trace: tls_layer_impl::on_read()
2022-07-27 15:05:41 23028 1 Trace: CFtpControlSocket::OnReceive()
2022-07-27 15:05:41 23028 1 Error: Connection closed by server
2022-07-27 15:05:41 23028 1 Trace: CRealControlSocket::DoClose(66)
2022-07-27 15:05:41 23028 1 Trace: CControlSocket::DoClose(66)
2022-07-27 15:05:41 23028 1 Trace: CFtpControlSocket::ResetOperation(66)
2022-07-27 15:05:41 23028 1 Trace: CControlSocket::ResetOperation(66)
2022-07-27 15:05:41 23028 1 Trace: CFtpLogonOpData::Reset(66) in state 6
2022-07-27 15:05:41 23028 1 Error: Could not connect to server
2022-07-27 15:05:41 23028 1 Trace: CFileZillaEnginePrivate::ResetOperation(66)
2022-07-27 15:05:41 23028 1 Status: Waiting to retry...
2022-07-27 15:05:46 23028 1 Trace: CRealControlSocket::DoClose(66)
2022-07-27 15:05:46 23028 1 Trace: CControlSocket::DoClose(66)
2022-07-27 15:05:46 23028 1 Trace: CFtpControlSocket::ResetOperation(66)
2022-07-27 15:05:46 23028 1 Trace: CControlSocket::ResetOperation(66)
2022-07-27 15:05:46 23028 1 Trace: CFileZillaEnginePrivate::ResetOperation(66)
2022-07-27 15:05:46 23028 1 Trace: CControlSocket::DoClose(66)
2022-07-27 15:05:46 23028 1 Trace: CControlSocket::ResetOperation(66)
2022-07-27 15:05:46 23028 1 Trace: CFileZillaEnginePrivate::ResetOperation(66)
2022-07-27 15:05:46 23028 1 Trace: CControlSocket::SendNextCommand()
2022-07-27 15:05:46 23028 1 Trace: CFtpLogonOpData::Send() in state 0
2022-07-27 15:05:46 23028 1 Status: Resolving address of ftps.dojo.co
2022-07-27 15:05:46 23028 1 Status: Connecting to 3.228.61.22:21...
2022-07-27 15:05:46 23028 1 Status: Connection established, waiting for welcome message...
2022-07-27 15:05:46 23028 1 Trace: CFtpControlSocket::OnReceive()
2022-07-27 15:05:46 23028 1 Response: 220 Service ready for new user.
2022-07-27 15:05:46 23028 1 Trace: CFtpLogonOpData::ParseResponse() in state 1
2022-07-27 15:05:46 23028 1 Trace: CControlSocket::SendNextCommand()
2022-07-27 15:05:46 23028 1 Trace: CFtpLogonOpData::Send() in state 2
2022-07-27 15:05:46 23028 1 Command: AUTH TLS
2022-07-27 15:05:46 23028 1 Trace: CFtpControlSocket::OnReceive()
2022-07-27 15:05:46 23028 1 Response: 234 Command AUTH okay; starting TLS connection.
2022-07-27 15:05:46 23028 1 Trace: CFtpLogonOpData::ParseResponse() in state 2
2022-07-27 15:05:46 23028 1 Status: Initializing TLS...
2022-07-27 15:05:46 23028 1 Trace: tls_layer_impl::client_handshake()
2022-07-27 15:05:46 23028 1 Trace: tls_layer_impl::continue_handshake()
2022-07-27 15:05:46 23028 1 Trace: TLS handshakep: About to send CLIENT HELLO
2022-07-27 15:05:46 23028 1 Trace: TLS handshakep: Sent CLIENT HELLO
2022-07-27 15:05:46 23028 1 Trace: tls_layer_impl::on_send()
2022-07-27 15:05:46 23028 1 Trace: tls_layer_impl::continue_handshake()
2022-07-27 15:05:46 23028 1 Trace: tls_layer_impl::on_read()
2022-07-27 15:05:46 23028 1 Trace: tls_layer_impl::continue_handshake()
2022-07-27 15:05:46 23028 1 Trace: tls_layer_impl::on_read()
2022-07-27 15:05:46 23028 1 Trace: tls_layer_impl::continue_handshake()
2022-07-27 15:05:46 23028 1 Trace: TLS handshakep: Received SERVER HELLO
2022-07-27 15:05:46 23028 1 Trace: TLS handshakep: Processed SERVER HELLO
2022-07-27 15:05:46 23028 1 Trace: TLS handshakep: Received CERTIFICATE
2022-07-27 15:05:46 23028 1 Trace: TLS handshakep: Processed CERTIFICATE
2022-07-27 15:05:46 23028 1 Trace: TLS handshakep: Received SERVER KEY EXCHANGE
2022-07-27 15:05:46 23028 1 Trace: TLS handshakep: Processed SERVER KEY EXCHANGE
2022-07-27 15:05:46 23028 1 Trace: TLS handshakep: Received SERVER HELLO DONE
2022-07-27 15:05:46 23028 1 Trace: TLS handshakep: Processed SERVER HELLO DONE
2022-07-27 15:05:46 23028 1 Trace: TLS handshakep: About to send CLIENT KEY EXCHANGE
2022-07-27 15:05:46 23028 1 Trace: TLS handshakep: Sent CLIENT KEY EXCHANGE
2022-07-27 15:05:46 23028 1 Trace: TLS handshakep: About to send FINISHED
2022-07-27 15:05:46 23028 1 Trace: TLS handshakep: Sent FINISHED
2022-07-27 15:05:46 23028 1 Trace: tls_layer_impl::on_read()
2022-07-27 15:05:46 23028 1 Trace: tls_layer_impl::continue_handshake()
2022-07-27 15:05:46 23028 1 Trace: TLS handshakep: Received NEW SESSION TICKET
2022-07-27 15:05:46 23028 1 Trace: TLS handshakep: Processed NEW SESSION TICKET
2022-07-27 15:05:46 23028 1 Trace: tls_layer_impl::on_read()
2022-07-27 15:05:46 23028 1 Trace: tls_layer_impl::continue_handshake()
2022-07-27 15:05:46 23028 1 Trace: TLS handshakep: Received FINISHED
2022-07-27 15:05:46 23028 1 Trace: TLS handshakep: Processed FINISHED
2022-07-27 15:05:46 23028 1 Trace: TLS Handshake successful
2022-07-27 15:05:46 23028 1 Trace: Protocol: TLS1.2, Key exchange: ECDHE-SECP384R1-RSA-SHA384, Cipher: AES-128-GCM, MAC: AEAD, ALPN:
2022-07-27 15:05:46 23028 1 Trace: tls_layer_impl::verify_certificate()
2022-07-27 15:05:46 23028 1 Trace: System trust store decision: true
2022-07-27 15:05:46 23028 1 Trace: Sending certificate_verification_event
2022-07-27 15:05:46 23028 1 Trace: CFtpControlSocket::SetAsyncRequestReply
2022-07-27 15:05:46 23028 1 Trace: set_verification_result(true)
2022-07-27 15:05:46 23028 1 Status: TLS connection established.
2022-07-27 15:05:46 23028 1 Trace: CControlSocket::SendNextCommand()
2022-07-27 15:05:46 23028 1 Trace: CFtpLogonOpData::Send() in state 6
2022-07-27 15:05:46 23028 1 Command: USER jake
2022-07-27 15:05:46 23028 1 Trace: CFtpControlSocket::OnReceive()
2022-07-27 15:05:46 23028 1 Trace: tls_layer_impl::on_read()
2022-07-27 15:05:46 23028 1 Trace: CFtpControlSocket::OnReceive()
2022-07-27 15:05:46 23028 1 Response: 331 User name okay, need password for jake.
2022-07-27 15:05:46 23028 1 Trace: CFtpLogonOpData::ParseResponse() in state 6
2022-07-27 15:05:46 23028 1 Trace: CControlSocket::SendNextCommand()
2022-07-27 15:05:46 23028 1 Trace: CFtpLogonOpData::Send() in state 6
2022-07-27 15:05:46 23028 1 Command: PASS *************
2022-07-27 15:05:46 23028 1 Trace: tls_layer_impl::on_read()
2022-07-27 15:05:46 23028 1 Trace: CFtpControlSocket::OnReceive()
2022-07-27 15:05:46 23028 1 Error: Connection closed by server
2022-07-27 15:05:46 23028 1 Trace: CRealControlSocket::DoClose(66)
2022-07-27 15:05:46 23028 1 Trace: CControlSocket::DoClose(66)
2022-07-27 15:05:46 23028 1 Trace: CFtpControlSocket::ResetOperation(66)
2022-07-27 15:05:46 23028 1 Trace: CControlSocket::ResetOperation(66)
2022-07-27 15:05:46 23028 1 Trace: CFtpLogonOpData::Reset(66) in state 6
2022-07-27 15:05:46 23028 1 Error: Could not connect to server
2022-07-27 15:05:46 23028 1 Trace: CFileZillaEnginePrivate::ResetOperation(66)

[botg]

It's a server-side issue. Something wrong with the server configuration or the user account in question.

Contact your server administrator or server hosting provider for further assistance.

[jakelester66]

Thank you for the fast reply. Yes, we also believe it to be a server-side issue... however we cannot figure out why.

I forgot to mention in my original post that we are using AWS Transfer Family to host the FTPS server.

@botg do you have any suggestions for how to debug to find out _what_ is wrong with the server configuration? We've tried whitelisting IP addresses for VPC security groups.

[botg]

The server logs would be a start.