[jira] [Created] (SSHD-903) SFTP version negotiation does not work

["Mark Ebbers (JIRA)" <ji...@apache.org>]

Mark Ebbers created SSHD-903:
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             Summary: SFTP version negotiation does not work  
                 Key: SSHD-903
                 URL: https://issues.apache.org/jira/browse/SSHD-903
             Project: MINA SSHD
          Issue Type: Bug
    Affects Versions: 2.2.0
            Reporter: Mark Ebbers
         Attachments: sftp-version-1.png, sftp-version-2.png

I have some problems with uploading files to our MINA SSHD based SFTP server when using ,different version, of WinSCP as SFTP client. WinSCP is configured to use version 6 of the SFTP protocol if possible. 

Uploading a file of ~ 45KB sometimes result in a file of 32711 bytes where in the data is not appended (from the second SFTP packet) but overwritten. (But did not pin point the exact bug)

As a temporary solution I found, in issue SSHD-874, a comment which suggest to force the server to use sftp-protocol version 3. If I do this I expect the server to negotiate with the client that version 3 should be used instead of version 6. But what happens is that the server sends a not supported message.

 

I think that the AbstractSftpSubsystemHelper::checkVersionCompatibility() is the problem.

See my screenshots. As you can see the version proposed by WinSCP is version 6. I forced the server on version 3.



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