mRemoteNg bug: No supported authentication methods available

Unable to connect to the server via SSH using mRemoteNG? How to fix the 'No supported authentication methods available' error when connecting to an Ubuntu 22.04+ server via SSH? How to update the Putty version for mRemoteNG? Read the article to find out.

What is mRemoteNG?

mRemoteNG is a free tool with a user-friendly graphical interface for managing remote connections via RDP, SSH, VNC, and other protocols. Under the hood, it uses Putty for connections, though an older version.

What could go wrong?

Changing the format of Putty ppk keys
In Ubuntu 22.04, there are increased security requirements for SSH keys, such as RSA encryption no longer being supported.

How to hix this?

Putty 0.81+ for mRemoteNG

mRemoteNG includes a modified version of puttyNG that improves compatibility between mRemoteNG and Putty. Connection issues may arise with older versions of Putty, especially on servers like Ubuntu 22, which expect PubkeyAcceptedAlgorithms. These issues can hinder establishing a secure connection. To address this problem, either update mRemoteNG to version 1.77.2 or newer, or manually replace PuTTYNG.exe.

To do this, download the latest version of PuTTYNG.exe. You can either manually replace the PuTTYNG.exe file in the mRemoteNG installation directory or do it through the interface. To do it through the interface, open "File -> Options".

Navigate to the "Advanced" tab.

Check the box "Use custom Putty path:".

Select the downloaded PuTTYNG.exe file on your computer.

Profit!

RSA in Ubuntu 22.04

If there is a problem with RSA key encryption, generate new keys with a new secure algorithm:

ssh-keygen -t rsa-sha2-512 -b 4096

If this is not possible, then you can enable rsa encryption for sshd manually on the server by editing the config /etc/ssh/sshd_config:

HostKeyAlgorithms +ssh-rsa
PubkeyAcceptedKeyTypes +ssh-rsa

Then restart sshd: sudo systemctl restart sshd