How do I connect via SFTP?

[jasjas]

Box: Vu+ Duo 2, with BH 3.0.2 (Oct 16). Access is from a remote location, using ddns. OpenWebIF works, as does SSH and WinSCP using SCP protocol.
Problem: SCP does not allow resume, whereas it seems WinSCP+SFTP does. Resume is critical for large recording files.
FileZilla:
I get this response:
11:01:53 Status: Connecting to somehwhere.ddns.net...
11:01:53 Response: fzSftp started, protocol_version=7
11:01:53 Command: open "root@somehwhere.ddns.net" 22
11:01:59 Command: Trust new Hostkey: Once
11:02:00 Command: Pass: **********
11:02:03 Status: Connected to somehwhere.ddns.net
11:02:03 Error: Received unexpected end-of-file from SFTP server
11:02:03 Error: Could not connect to server

What is it looking for to get EOF??

WinSCP:
This is in the log file:
. 2016-12-31 11:21:24.593 We claim version: SSH-2.0-WinSCP_release_5.9.2
. 2016-12-31 11:21:24.962 Server version: SSH-2.0-dropbear_2014.66
. 2016-12-31 11:21:24.962 We believe remote version has SSH-2 channel request bug
. 2016-12-31 11:21:24.962 Using SSH protocol version 2
. 2016-12-31 11:21:24.963 Have a known host key of type rsa2
. 2016-12-31 11:21:24.963 Doing ECDH key exchange with curve Curve25519 and hash SHA-256
......blah blah
. 2016-12-31 11:21:27.833 Access granted
. 2016-12-31 11:21:27.833 Opening session as main channel
. 2016-12-31 11:21:28.195 Opened main channel
. 2016-12-31 11:21:28.974 Started a shell/command
. 2016-12-31 11:21:29.022 --------------------------------------------------------------------------
. 2016-12-31 11:21:29.022 Using SFTP protocol.
. 2016-12-31 11:21:29.023 Doing startup conversation with host.
! 2016-12-31 11:21:29.023 sh: /usr/lib/openssh/sftp-server: No such file or directory
. 2016-12-31 11:21:29.023 Server sent command exit status 127
. 2016-12-31 11:21:29.023 Disconnected: All channels closed
* 2016-12-31 11:21:29.141 (EFatal)

There certainly is no /usr/lib/openssh folder (just /usr/lib/opkg), so what can I do to give WinSCP what it wants, or where is the SFTP server on the Vu box? The standard/default VSFTP is running.

Many thanks for any leads.

 

[jasjas]

- site timed out so much that I could not edit the above.
Some more lines from the WinSCP log

. 2016-12-31 11:21:24.593 We claim version: SSH-2.0-WinSCP_release_5.9.2
. 2016-12-31 11:21:24.962 Server version: SSH-2.0-dropbear_2014.66
. 2016-12-31 11:21:24.962 We believe remote version has SSH-2 channel request bug
. 2016-12-31 11:21:24.962 Using SSH protocol version 2
. 2016-12-31 11:21:24.963 Have a known host key of type rsa2
. 2016-12-31 11:21:24.963 Doing ECDH key exchange with curve Curve25519 and hash SHA-256
......blah blah
. 2016-12-31 11:21:27.833 Access granted
. 2016-12-31 11:21:27.833 Opening session as main channel
. 2016-12-31 11:21:28.195 Opened main channel
. 2016-12-31 11:21:28.974 Started a shell/command
. 2016-12-31 11:21:29.022 --------------------------------------------------------------------------
. 2016-12-31 11:21:29.022 Using SFTP protocol.
. 2016-12-31 11:21:29.023 Doing startup conversation with host.
! 2016-12-31 11:21:29.023 sh: /usr/lib/openssh/sftp-server: No such file or directory
. 2016-12-31 11:21:29.023 Server sent command exit status 127
. 2016-12-31 11:21:29.023 Disconnected: All channels closed
* 2016-12-31 11:21:29.141 (EFatal)

 

[jasjas]

Further finds:
I read here that vsftp is not an sftp server, and various forums suggest running:
opkg install openssh-sftp-server
but, this fails with 'unknown package' and the output of [openpkg list] does not include this openssh... package or anything resembling it. Someone else refers to open-sftp-server but this must be a typo and has the same response.
So, where to get/configure an actual resume-capable SFTP server for Vu+ Duo 2/BH 3.0.2 that either WinSCP or FileZill will talk to??

 

[fta]

Have you tried to install the OpenBH package?