Request: Update SFTP library to support Ed25519 and modern SSH

[moxuanyuan]

Hi Multi Commander Team,

First of all, thank you for developing such an amazing and efficient dual-panel file manager. It has been a core part of my daily workflow.

I would like to request an upgrade for the built-in SFTP/SCP plugin. Currently, when trying to connect to modern Linux servers (such as Debian 12, Ubuntu 22.04+, or modern LXC containers), the connection consistently fails during the handshake phase, resulting in the following log errors:
Key exchange method : (null)
Authentication handshake failed : No method negotiated

The Root Cause:
Modern OpenSSH servers have completely deprecated legacy and insecure algorithms by default (such as ssh-rsa with SHA-1, diffie-hellman-group14-sha1, and CBC ciphers). They now require modern cryptography like Ed25519, rsa-sha2-256, or aes128/256-gcm.

Unfortunately, Multi Commander's internal SFTP library (seemingly based on an older version of libssh2) doesn't support these modern standards yet. To make it work, users are forced to manually downgrade their server's SSH security configurations, which poses significant security risks even in a local HomeLab environment.

Suggested Improvement:
Could you please consider updating the underlying SSH/SFTP library (e.g., upgrading to the latest version of libssh2 or migrating to a more modern SSH backend) in an upcoming release? Supporting Ed25519 keys and modern KEX/Cipher algorithms would bring Multi Commander's SFTP plugin back to modern standards.

Thank you for your time and continuous effort in improving this great tool!

Best regards

[Mathias (Author)]

MC is using newest version of LibSSH2 ( v1.11.1 )

Last time I check it was an issue with LibSSH2 not supporting it on Windows 7 since it require method that only exists on Windows 10. Problem is that they are not checking if that method exists dynamically. so it is required at build time.  so then MC will not work on Win7. (Still around 3-4% of users is using MC on Win7, But more and more issues popup to be able to support Win7.  )
I been thinking about building two version of the FS-SFTP extension, (Win7 version and one normal for newer Windows ) But that require a lot of handling and thing around that need to be changed. And I have not had time to investigate all that