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https://issues.apache.org/jira/browse/SSHD-998?focusedWorklogId=434496&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-434496
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ASF GitHub Bot logged work on SSHD-998:
---------------------------------------

                Author: ASF GitHub Bot
            Created on: 18/May/20 17:07
            Start Date: 18/May/20 17:07
    Worklog Time Spent: 10m 
      Work Description: lgoldstein opened a new pull request #133:
URL: https://github.com/apache/mina-sshd/pull/133


   


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Issue Time Tracking
-------------------

            Worklog Id:     (was: 434496)
    Remaining Estimate: 0h
            Time Spent: 10m

> respect SftpVersionSelector when establishing a new connection
> --------------------------------------------------------------
>
>                 Key: SSHD-998
>                 URL: https://issues.apache.org/jira/browse/SSHD-998
>             Project: MINA SSHD
>          Issue Type: Bug
>    Affects Versions: 2.4.0
>            Reporter: Holger Rehn
>            Assignee: Lyor Goldstein
>            Priority: Major
>              Labels: features, patch, performance
>         Attachments: patch.diff
>
>          Time Spent: 10m
>  Remaining Estimate: 0h
>
> Even if using an SftpVersionSelector (e.g. created by 
> SftpVersionSelector.fixedVersionSelector), SSHD sends the maximum protocol 
> version that is supported (namely 6) in the initial SSH_FXP_INIT datagram. 
> This behaviour is hard-coded and may cause problems if the server doesn't 
> correctly handle the request/support protocol version 6. One of our customers 
> is using a server that initially accepts protocol version 6, but then fails 
> every single request by sending invalid data. Actually, the server only 
> correctly supports SFTP 3, so this clearly is a bug in the server 
> implementation - but could be circumvented quite easily by starting with 
> protocol version 3. Furthermore an additional (and actually unnecessary) 
> version renegotiation may be required later.
> If using an SftpVersionSelector that prefers a certain protocol version other 
> than 6 (custom or created by SftpVersionSelector.preferredVersionSelector), 
> an additional (and actually unnecessary) network round trip is required for 
> protocol version renegotiation. 
>  
> Please find attached a minimally invasive patch against the official 2.4.0 
> source to respect the version(s) accepted by an SftpVersionSelector for 
> choosing the initial protocol version.  



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