Messages

1

Support and Feedback / Re: SFTP Connection fails

« on: Today at 08:19:28 »

I ran into the exact same issue. Here is the reason and how to fix it.

The Root Cause
Multi Commander's built-in SFTP module uses an outdated libssh2 library. It only supports legacy algorithms (like ssh-rsa with SHA-1, diffie-hellman-group14-sha1). Modern Linux servers (Debian 12, Ubuntu 22.04+) disable these by default for security, causing the handshake to fail with (null) errors.

Solution 1: Modify Server Config (Workaround)
If you can manage the server, you can force it to allow legacy algorithms:

Edit SSH config: sudo nano /etc/ssh/sshd_config

Add these lines to the very bottom:

KexAlgorithms +diffie-hellman-group14-sha1,diffie-hellman-group-exchange-sha256
Ciphers +aes128-cbc,aes256-cbc,aes128-ctr,aes256-ctr
HostKeyAlgorithms +ssh-rsa
PubkeyAcceptedKeyTypes +ssh-rsa

Restart SSH: sudo systemctl restart ssh

In Multi Commander, clear all keyfile paths and use pure password authentication (it cannot parse modern Ed25519 keys).

Solution 2: Mount as Local Drive (Recommended)
Instead of degrading server security, use tools like RaiDrive or Rclone to mount your SFTP server as a local Windows drive letter (e.g., Z:). You can then manage files in Multi Commander just like a local drive with full speed and modern security.

Hope the developer can update the underlying library soon!

2

Feature Requests and Suggestions / Request: Update SFTP library to support Ed25519 and modern SSH

« on: Today at 08:14:08 »

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