FS#76253 - [libssh] Possible bug with hosts requiring KexAlgorithms directive

Attached to Project: Arch Linux
Opened by drws (drws) - Thursday, 20 October 2022, 08:19 GMT
Last edited by Antonio Rojas (arojas) - Tuesday, 22 November 2022, 23:04 GMT
Task Type Bug Report
Category Packages: Extra
Status Closed
Assigned To Antonio Rojas (arojas)
Christian Hesse (eworm)
Architecture All
Severity Low
Priority Normal
Reported Version
Due in Version Undecided
Due Date Undecided
Percent Complete 100%
Votes 0
Private No

Details

Description:

I've been using Remmina to connect through an SSH tunnel which requires me to specify additional kex algorithms. Remmina uses libssh and KexAlgorithms are specified in the SSH host configuration file (~/.ssh/config). Such connections were working for a long time until recently. Now Remmina complains that no matching kex algos are found between the client and the server. Manual SSH connection using the same host configuration works OK.

At first glance it seemed a Remmina bug, but I was told that's probably not the case:
https://gitlab.com/Remmina/Remmina/-/issues/2802

There was an update of OpenSSH recently so it might be related to that. Possibly libssh only needs a rebuild?

Additional info:
* package version: 0.10.4-1

Steps to reproduce:
1. have a host ready that only has older kex algos not in the default list
1. specify the host together with a KexAlgorithms directive in an SSH config file
2. connect to the host with an application that uses SSH through libssh
This task depends upon

Closed by  Antonio Rojas (arojas)
Tuesday, 22 November 2022, 23:04 GMT
Reason for closing:  Upstream
Comment by Toolybird (Toolybird) - Friday, 21 October 2022, 22:29 GMT
> which requires me to specify additional kex algorithms

Details?

> until recently

How recent? libssh was Last Updated: 2022-09-07 19:29 UTC.

Just because an upstream points the finger back at the distro, it doesn't make it true. You'll need to debug this somehow. It might be worth heading to the support channels (forum/IRC/etc) to see if anyone can help?

> Possibly libssh only needs a rebuild?

It's unlikely, but this is something you could easily test yourself. FWIW, libssh makedepends on openssh but I couldn't determine why after 2 minutes of looking. libssh will still build when openssh is missing.
Comment by Toolybird (Toolybird) - Monday, 21 November 2022, 21:36 GMT
Before closing this as "no response", I will assign to the libssh PM's to see if they have any thoughts?
Comment by Christian Hesse (eworm) - Monday, 21 November 2022, 22:03 GMT
I do not think a rebuild will help here. Some more insight would help a lot... OpenSSH version of the host, configuration in ~/.ssh/config and possibly ssh with debug output connecting to the host...
Comment by drws (drws) - Tuesday, 22 November 2022, 23:00 GMT
It appears that there are more directives Remmina (or libssh) misses. The host port is read and used, but the debug output always contains 22. IdentityFile also appears to not be considered anymore. And key algos are always "(null)" in the output whether the KexAlgorithms are specified in .ssh/config or not.

Due to these developments I think it's best this one is closed.

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