SFTP, Remote side unexpectedly closed network connection

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JohnWis
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SFTP, Remote side unexpectedly closed network connection

WinSCP version 5.17.6
Worked with version 5.9.3
Windows server 2016 (in Citrix)
SFTP
Using the GUI
Error: Remote side unexpectedly closed network connection or Network error: Software caused connection abort
When setting up a connection to a Linux server, an error occur, connection can't be establised.
With the old version of WinSCP there is no issue to connect to these Linux servers, It is not 1 server but a pool of servers not working.
The WinSCP client (old en new) are running on a XenApp environment.
Description: 3 sessions, all failed but with 2 different messages

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martin
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Re: SFTP, Remote side unexpectedly closed network connection

Can you post a log file of a successful session from the old version of WinSCP?

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Francis
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I updated to WinSCP 5.17.7 a few days ago and met a similar problem:
The administrator of the remote SFTP site tells me that the server hosting the SFTP receives a GET/HTTP request (after the connection). As a consequence my IP is banned and I cannot reconnect.

NB: the connection of the SFTP site use a tunnel. I can connect and reconnect with command line (or Java JSch).

2020-09-09T12:04:28+02:00 sftp-g03 sshd[211583]: [ID 800047 auth.info] Accepted publickey for XXX from XXX.XXX.XXX.XXX port 49912 ssh2: RSA SHA256:XXXX
2020-09-09T12:04:29+02:00 sftp-g03 sshd[211613]: [ID 800047 auth.info] Bad protocol version identification 'GET / HTTP/1.1' from XXX.XXX.XXX.XXX port 49914

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martin
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Re: SFTP, Remote side unexpectedly closed network connection

Thanks for the log. It didn't reveal anything useful though. Did you have an access to server-side logs? Don't you need to whitelist the new version somehow in your "XenApp environment"?

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martin
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Francis wrote:

I updated to WinSCP 5.17.7 a few days ago and met a similar problem:
The administrator of the remote SFTP site tells me that the server hosting the SFTP receives a GET/HTTP request (after the connection). As a consequence my IP is banned and I cannot reconnect.
This does not seem related. Please start a new thread and post log files from both old and the new version of WinSCP.

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JohnWis
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SFTP, Remote side unexpectedly closed network connection

The log file from the linux server gives this message:
2020-09-23T10:47:35.129652+02:00 TController-Databus01-P-ACC sshd[348917]: fatal: No supported key exchange algorithms found [preauth]
Sshd_config server
Ciphers aes128-ctr,aes192-ctr,aes256-ctr
KexAlgorithms diffie-hellman-group-exchange-sha256
MACs hmac-sha2-256,hmac-sha2-512
And WinSCP should support this, but is this still in the current release
https://winscp.net/eng/docs/tls_ciphersuites

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JohnWis
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SFTP, Remote side unexpectedly closed network connection

We already did

Version 5.9.3 ok
Version 5.10 Nok
Version 5.17.6 Nok

Do you want us to try the versions between 5.9.3 and 5.10?

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martin
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Re: SFTP, Remote side unexpectedly closed network connection

JohnWis wrote:

Do you want us to try the versions between 5.9.3 and 5.10?
Yes please.

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JohnWis
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SFTP, Remote side unexpectedly closed network connection

Tested again
Version 5.9.6 is OK
Version 5.10.4.RC NOK
Version 5.11 is NOK

So there is a difference after version 5.9.6

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JohnWis
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Re: SFTP, Remote side unexpectedly closed network connection

What should we do to analyse or solve if this is the problem we have.

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martin
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Re: SFTP, Remote side unexpectedly closed network connection

Upgrade your OpenSSH installation.
Or, if you register, I can send you a copy of WinSCP that does not trigger the wrong rule.

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JohnWis
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Re: SFTP, Remote side unexpectedly closed network connection

I just registered, can you send me a copy of WinSCP that does not trigger the wrong rule.

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shashi1409
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Re: SFTP, Remote side unexpectedly closed network connection

Hi Martin, I am having the same issue, can you please send me the Winscp version that will not raise this exception.

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martin
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Re: SFTP, Remote side unexpectedly closed network connection

shashi1409 wrote:

Hi Martin, I am having the same issue, can you please send me the Winscp version that will not raise this exception.
Can you please elaborate on how your problem is the same? Does an old version of WinSCP also work for you, but the new one does not? Post logs from both versions.

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