Bdtyktl

I'm using pure-ftpd 1.0.46 on Ubuntu 18.04 as the server, with TLS and certificates signed by Let's Encrypt. I have no issues connecting and transferring over WAN. I'm using passive mode, the ports are properly forwarded, and I've configured pure-ftpd to respond with its WAN IP.

However, I can not make a connection over LAN, as it complains about TLS connection termination. I've tried several clients and they all have some kind of timeout error. I suspect part of the problem may be my DNS setup. I have a domain name that points to my WAN, and that is what I usually use to connect to the server. But I have my local DNS server respond with the LAN IP for the ftp machine. So when I'm at home, my laptop makes the ftp connection to 192.168.1.2, but the PASV response is my WAN IP 74.x.x.x. In theory, my router should support NAT loopback, which sends traffic originating in the LAN and destined for the WAN IP back to the local IP to which its forwarded. This seems to work fine for http, and I assumed since the client initiates the passive mode data tcp connection, it should work for that as well. But maybe there's some routing detail I'm missing. Could this be the problem?

Client log:

Status: Connecting to 192.168.1.2:21...

Status: Connection established, waiting for welcome message...

Trace:  CFtpControlSocket::OnReceive()

Response:   220---------- Welcome to Pure-FTPd [privsep] [TLS] ----------

Response:   220-You are user number 9 of 50 allowed.

Response:   220-Local time is now 16:01. Server port: 21.

Response:   220-This is a private system - No anonymous login

Response:   220-IPv6 connections are also welcome on this server.

Response:   220 You will be disconnected after 15 minutes of inactivity.

Trace:  CFtpLogonOpData::ParseResponse() in state 1

Trace:  CControlSocket::SendNextCommand()

Trace:  CFtpLogonOpData::Send() in state 2

Command:    AUTH TLS

Trace:  CFtpControlSocket::OnReceive()

Response:   234 AUTH TLS OK.

Trace:  CFtpLogonOpData::ParseResponse() in state 2

Status: Initializing TLS...

Trace:  CTlsSocketImpl::Handshake()

Trace:  CTlsSocketImpl::ContinueHandshake()

Trace:  TLS handshake: About to send CLIENT HELLO

Trace:  TLS handshake: Sent CLIENT HELLO

Trace:  CTlsSocketImpl::OnSend()

Trace:  CTlsSocketImpl::OnRead()

Trace:  CTlsSocketImpl::ContinueHandshake()

Trace:  CTlsSocketImpl::OnRead()

Trace:  CTlsSocketImpl::ContinueHandshake()

Trace:  TLS handshake: Received SERVER HELLO

Trace:  TLS handshake: Processed SERVER HELLO

Trace:  CTlsSocketImpl::OnRead()

Trace:  CTlsSocketImpl::ContinueHandshake()

Trace:  TLS handshake: Received CERTIFICATE

Trace:  TLS handshake: Processed CERTIFICATE

Trace:  TLS handshake: Received SERVER KEY EXCHANGE

Trace:  TLS handshake: Processed SERVER KEY EXCHANGE

Trace:  TLS handshake: Received SERVER HELLO DONE

Trace:  TLS handshake: Processed SERVER HELLO DONE

Trace:  TLS handshake: About to send CLIENT KEY EXCHANGE

Trace:  TLS handshake: Sent CLIENT KEY EXCHANGE

Trace:  TLS handshake: About to send FINISHED

Trace:  TLS handshake: Sent FINISHED

Trace:  CTlsSocketImpl::OnRead()

Trace:  CTlsSocketImpl::ContinueHandshake()

Trace:  TLS handshake: Received NEW SESSION TICKET

Trace:  TLS handshake: Processed NEW SESSION TICKET

Trace:  TLS handshake: Received FINISHED

Trace:  TLS handshake: Processed FINISHED

Trace:  TLS Handshake successful

Trace:  Protocol: TLS1.2, Key exchange: ECDHE-RSA, Cipher: AES-256-GCM, MAC: AEAD

Status: Verifying certificate...

Status: TLS connection established.

Trace:  CControlSocket::SendNextCommand()

Trace:  CFtpLogonOpData::Send() in state 5

Command:    USER *****

Trace:  CTlsSocketImpl::OnRead()

Trace:  CFtpControlSocket::OnReceive()

Response:   331 User ******* OK. Password required

Trace:  CFtpLogonOpData::ParseResponse() in state 5

Trace:  CControlSocket::SendNextCommand()

Trace:  CFtpLogonOpData::Send() in state 5

Command:    PASS **********

Trace:  CTlsSocketImpl::OnRead()

Trace:  CFtpControlSocket::OnReceive()

Response:   230 OK. Current directory is /

Trace:  CFtpLogonOpData::ParseResponse() in state 5

Trace:  CControlSocket::SendNextCommand()

Trace:  CFtpLogonOpData::Send() in state 9

Command:    OPTS UTF8 ON

Trace:  CTlsSocketImpl::OnRead()

Trace:  CFtpControlSocket::OnReceive()

Response:   200 OK, UTF-8 enabled

Trace:  CFtpLogonOpData::ParseResponse() in state 9

Trace:  CControlSocket::SendNextCommand()

Trace:  CFtpLogonOpData::Send() in state 10

Command:    PBSZ 0

Trace:  CTlsSocketImpl::OnRead()

Trace:  CFtpControlSocket::OnReceive()

Response:   200 PBSZ=0

Trace:  CFtpLogonOpData::ParseResponse() in state 10

Trace:  CControlSocket::SendNextCommand()

Trace:  CFtpLogonOpData::Send() in state 11

Command:    PROT P

Trace:  CTlsSocketImpl::OnRead()

Trace:  CFtpControlSocket::OnReceive()

Response:   200 Data protection level set to "private"

Trace:  CFtpLogonOpData::ParseResponse() in state 11

Status: Logged in

Trace:  Measured latency of 3 ms

Trace:  CFtpControlSocket::ResetOperation(0)

Trace:  CControlSocket::ResetOperation(0)

Trace:  CFtpLogonOpData::Reset(0) in state 14

Trace:  CFileZillaEnginePrivate::ResetOperation(0)

Status: Retrieving directory listing...

Trace:  CControlSocket::SendNextCommand()

Trace:  CFtpListOpData::Send() in state 0

Trace:  CFtpChangeDirOpData::Send() in state 0

Trace:  CFtpChangeDirOpData::Send() in state 1

Command:    PWD

Trace:  CTlsSocketImpl::OnRead()

Trace:  CFtpControlSocket::OnReceive()

Response:   257 "/" is your current location

Trace:  CFtpChangeDirOpData::ParseResponse() in state 1

Trace:  CFtpControlSocket::ResetOperation(0)

Trace:  CControlSocket::ResetOperation(0)

Trace:  CFtpChangeDirOpData::Reset(0) in state 1

Trace:  CFtpListOpData::SubcommandResult(0) in state 1

Trace:  CControlSocket::SendNextCommand()

Trace:  CFtpListOpData::Send() in state 2

Trace:  CFtpRawTransferOpData::Send() in state 1

Command:    TYPE I

Trace:  CTlsSocketImpl::OnRead()

Trace:  CFtpControlSocket::OnReceive()

Response:   200 TYPE is now 8-bit binary

Trace:  CFtpRawTransferOpData::ParseResponse() in state 1

Trace:  CControlSocket::SendNextCommand()

Trace:  CFtpRawTransferOpData::Send() in state 2

Command:    PASV

Trace:  CTlsSocketImpl::OnRead()

Trace:  CFtpControlSocket::OnReceive()

Response:   227 Entering Passive Mode (75,85,*,*,46,161)

Trace:  CFtpRawTransferOpData::ParseResponse() in state 2

Trace:  CControlSocket::SendNextCommand()

Trace:  CFtpRawTransferOpData::Send() in state 4

Trace:  Destination IP of data connection does not match peer IP of control connection. Not binding source address of data connection.

Command:    MLSD

Trace:  CTransferSocket::OnConnect

Trace:  CTlsSocketImpl::Handshake()

Trace:  Trying to resume existing TLS session.

Trace:  CTlsSocketImpl::ContinueHandshake()

Trace:  TLS handshake: About to send CLIENT HELLO

Trace:  TLS handshake: Sent CLIENT HELLO

Trace:  CTlsSocketImpl::OnSend()

Trace:  CTlsSocketImpl::OnSend()

Trace:  CTlsSocketImpl::OnRead()

Trace:  CTlsSocketImpl::ContinueHandshake()

Trace:  CTlsSocketImpl::OnRead()

Trace:  CTlsSocketImpl::ContinueHandshake()

Trace:  CTlsSocketImpl::Failure(-110)

Error:  GnuTLS error -110: The TLS connection was non-properly terminated.

Status: Server did not properly shut down TLS connection

Trace:  CTlsSocketImpl::OnSocketEvent(): close event received

Trace:  CTransferSocket::OnClose(106)

Error:  Transfer connection interrupted: ECONNABORTED - Connection aborted

Trace:  CTransferSocket::TransferEnd(3)

Trace:  CFtpControlSocket::TransferEnd()

Trace:  CFtpControlSocket::ResetOperation(10)

Trace:  CControlSocket::ResetOperation(10)

Trace:  CFtpRawTransferOpData::Reset(10) in state 6

Trace:  CFtpControlSocket::ResetOperation(10)

Trace:  CControlSocket::ResetOperation(10)

Trace:  CFtpListOpData::Reset(10) in state 3

Error:  Directory listing aborted by user

Trace:  CFileZillaEnginePrivate::ResetOperation(10)

Status: Disconnected from server

Trace:  CRealControlSocket::DoClose(66)

Trace:  CControlSocket::DoClose(66)

Trace:  CFtpControlSocket::ResetOperation(66)

Trace:  CControlSocket::ResetOperation(66)

Trace:  CFileZillaEnginePrivate::ResetOperation(66)

Trace:  CRealControlSocket::DoClose(66)

Trace:  CControlSocket::DoClose(66)

Trace:  CControlSocket::DoClose(66)

Trace:  CFileZillaEnginePrivate::ResetOperation(0)

Destination IP of data connection does not match peer IP of control connection. Not binding source address of data connection.

That’s pretty definitive. The client is not going to accept a control connection established over a local IP and a data connection over a different IP.

Best solution should be to just change the local DNS to provide the public IP address. Shouldn’t be any harm in that if it works.