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[Richard Ems]

Hi all,

For a customer I configured a new workstation with Rocky Linux 9.7 and latest versions of VirtualGL and TurboVNC.

The users connect from MacOS laptops with TurboVNC 3.2.1.
Two users can connect without issues, one gets the error message below.

Any ideas what may be the issue?

Thanks,
Richard

PS: more info: all 3 users can connect to an older workstation without issues. The two users that can connect to the new workstation have ARM MACs. The one that cannot has a Intel MAC.

[DRC]

That error comes from JSch, the TurboVNC Viewer's built-in SSH client. 
I think it may be due to either a badly-formatted SSH known_hosts file
or possibly an incompatibility, such as OpenSSH writing a known_hosts
entry using an encryption algorithm that JSch doesn't support.  I will
try to reproduce the problem and see if I can make the TurboVNC Viewer
handle it more gracefully.

[Richard Ems]

Hi DRC,

Many thanks for your answer.

I started now a VNC session for this user on a static port, I can connect from my OpenSUSE 15.6 laptop without issues.

But the user supposed to connect to this new VNC session gets the error messages attached.

He is connecting from MAC 13.4.

Other two users connecting with MAC 15.7 and 26.1 don't have these issues.

Could the "old" MACOS be the cause of this errors?

Many thanks again!

Richard

[DRC]

I don't know.  It could be that the older macOS version has an older version of OpenSSH that creates a known_hosts entry that JSch chokes on.  I need to reproduce the issue before I can say for sure.

DRC

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[DRC]

I was able to reproduce the issue by deleting a couple of bytes from a valid known_hosts entry.  OpenSSH handles such issues gracefully, by printing a debugging message about the bogus entry and continuing to parse the file.  I modified our SSH client to do likewise, so please try installing one of the pre-release builds (https://turbovnc.org/DeveloperInfo/PreReleases) on the client.

DRC

On 1/30/26 10:44 AM, Richard Ems wrote:

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