Question

SFTP connexion not working anymore

  • Posted on January 21, 2015
  • esiaoAsked by esiao

Hello I have a problem. I followed this tutorial : https://www.digitalocean.com/community/tutorials/how-to-use-filezilla-to-transfer-and-manage-files-securely-on-your-vps

It was working for months but since a week it’s not working anymore. I haven’t change anything and I’m not able to understand what’s happening through Filezilla’s log. Here it is.

Response:	fzSftp started
Trace:	CSftpControlSocket::ConnectParseResponse(fzSftp started)
Trace:	CSftpControlSocket::SendNextCommand()
Trace:	CSftpControlSocket::ConnectSend()
Command:	keyfile "C:\Users\Aurélien\my_keys\gg_private.ppk"
Trace:	CSftpControlSocket::ConnectParseResponse()
Trace:	CSftpControlSocket::SendNextCommand()
Trace:	CSftpControlSocket::ConnectSend()
Command:	open "xxx@xxx.xxx.xxx.xxx" 22
Trace:	Looking up host "xxx.xxx.xxx.xxx"
Trace:	Connecting to xxx.xxx.xxx.xxx port 22
Trace:	We claim version: SSH-2.0-PuTTY_Local:_Jan__7_2015_14:17:27
Trace:	Server version: SSH-2.0-OpenSSH_6.6.1p1 Ubuntu-2ubuntu2
Trace:	We believe remote version has SSH-2 channel request bug
Trace:	Using SSH protocol version 2
Trace:	Doing ECDH key exchange with hash SHA-256
Trace:	Host key fingerprint is:
Trace:	ecdsa-sha2-nistp256 d5:e8:ca:a6:69:ae:dd:68:21:07:1d:17:c7:48:86:9b
Command:	Trust new Hostkey: Once
Trace:	Initialised AES-256 SDCTR client->server encryption
Trace:	Initialised HMAC-SHA-256 client->server MAC algorithm
Trace:	Initialised AES-256 SDCTR server->client encryption
Trace:	Initialised HMAC-SHA-256 server->client MAC algorithm
Trace:	CControlSocket::DoClose(64)
Trace:	CSftpControlSocket::ResetOperation(66)
Trace:	CControlSocket::ResetOperation(66)
Error:	Could not connect to server
Trace:	CFileZillaEnginePrivate::ResetOperation(66)
Status:	Waiting to retry...

It seems to be a server problem as stated here Trace: We believe remote version has SSH-2 channel request bug

Thanks for the help you could bring me.


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Can be. But you can’t completely blame the server. There are multiple solutions for this

  1. Update your putty
  2. Modify ‘Algorithm Selection policy’ (In putty, Connection > SSH > Kex) in putty. Some policy may not work with the server. You need to change the order in it. ‘Diffie-Helman group 14’ or ‘Diffie-Helman group exchange’ on the top will normally work.

Most of the cases these worked for me.