SFTP connection suddenly doesn't work. Works in other applications.

[Menelo]

As of today I cannot connect via SFTP, it keeps popping error message:
[SFTP] Connection failed : kex error : no match for method kex algos: server [diffie-hellman-group-exchange-sha256], client [curve25519-sha256@libssh.org,ecdh-sha2-nistp256,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1]

I've tried connecting with WinSCP, and SFTP worked without issues, so I guess the problem is with NppFTP.

Debug Information

Notepad++ v7.3.3 (32-bit)
Build time : Mar 8 2017 - 03:37:37
Path : C:\Program Files (x86)\Notepad++\notepad++.exe
Admin mode : OFF
Local Conf mode : OFF
OS : Windows 10 (64-bit)
Plugins : mimeTools.dll NppConverter.dll NppExport.dll NppFTP.dll PluginManager.dll

version of Notepad++: v7.3.3 (32-bit)
type of FTP connection: SFTP
type of authentication: password

[chcg]

@Menelo NppFTP uses libssh to support sftp. The supported algorithms are the ones mentioned in the trace:

client [curve25519-sha256@libssh.org,ecdh-sha2-nistp256,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1]

, see https://www.libssh.org/features/

So there will be no support for diffie-hellman-group-exchange-sha256 without the support from libssh for it.

See also https://blog.gdssecurity.com/labs/2015/8/3/ssh-weak-diffie-hellman-group-identification-tool.html, where it is stated that this KEX Algorithm is part of RFC 4419.

Maybe you want to add a feature request at https://red.libssh.org/projects/libssh/issues.

Are you using NppFTP v0.27.1 ? If the support dropped lately that was probably a configuration change on server side.

[chcg]

@Menelo You may want to test current release https://github.com/ashkulz/NppFTP/releases/tag/v0.28.0 which contains updated libssh version 0.8.6 with support for additional algorithms.

[Ben-Voris]

Please, would you close this?

[chcg]

As there is no response from creator -> closed