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https://issues.apache.org/jira/browse/SSHD-998?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Holger Rehn updated SSHD-998:
-----------------------------
Description:
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.
was:
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 invative patch against the official 2.4.0
source to respect the version(s) accepted by an SftpVersionSelector for
choosing the initial protocol version.
> 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
> Priority: Major
> Labels: features, patch, performance
> Attachments: patch.diff
>
>
> 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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