SSH session issue with Ubuntu 22.x release

Products

• Automation Point

Issue/Introduction

Connecting to SSH sessions fails when trying to connect to an Ubuntu 22.x version

Environment

Release : 11.7

Resolution

For EARLIER Ubuntu versions ( before rel 22.x)
Attached is a TXT file to this case in the files_from_broadcom directory... 
The file is called set_SSHKnowProblems.txt ... 
Download the file and rename it to set_SSHKnowProblems.bat ... 

Execute this batch file as following:

set_SSHKnowProblems.bat sc_Session~Definition~Set~1.apm VR01_SSH 

The script will lookup session definition file "sc_Session~Definition~Set~1.apm" in the AP configuration file folder and set the SHH configuration key for the "VR01_SSH" SSH session.
Running the script again, the script will remove the existing SSH key. 
The script will not update a NON-SSH session. 
The script can be used in case similar issues with other SSH session encountered.

 

**** UBUNTU 22.x related:

Upon connecting to an SSH server/daemon, AP negotiates with it what algorithms will be used for the upcoming communication.

Part of the negotiations is an agreement on a Host Key algorithm acceptable for both AP and the SSH server.

AP always offers a fixed set of two Host Key Algorithms (i.e. "ssh-rsa, ssh-dss").

Offer on the part of the SSH server depends on its configuration. My GCP machine offers the following set of algorithms by default:

"rsa-sha2-512, rsa-sha2-256, ecdsa-sha2-nistp256, ssh-ed25519". 

Note there is no intersection between the AP and the SSH algorithms and that is causing the error in this case.

In order to fix the error modify /etc/ssh/sshd_config by appending the following lines to it:

/etc/ssh/sshd_config:
...
PubkeyAcceptedKeyTypes +ssh-rsa
HostKeyAlgorithms +ssh-rsa
...

And restarted the sshd daemon. After the restart, connect an AP SSH session again. This time the SSH server offered the following algorithms

"rsa-sha2-512, rsa-sha2-256, ssh-rsa, ecdsa-sha2-nistp256, ssh-ed25519"

Note the third position offers "ssh-rsa" algorithm as an acceptable Host Key algorithm. The connection attempt thus succeeded and the AP SSH session was able to connect to the SSH server and the GCP machine.

With the aforementioned /etc/ssh/sshd_config update it's possible to connect my AP SSh session to the Ubuntu 22.04 machine.