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unknown hostkey algorithm error





This article explains the meaning and possible causes of the unknown hostkey algorithm error, and if generated when making an SSH connection to the LoadMaster, what steps can be taken to overcome the error.


Product: LoadMaster

Version: Any

Platform: Any

Application: Any

Question/Problem Description:

What does the unknown hostkey algorithm error mean?

Steps to Reproduce:  
Error Message:

sshd[xxxx]: fatal: no hostkey alg [preauth]

Defect Number:  
Enhancement Number:  

This error can occur when the SSH daemon (sshd) is being presented with an unknown hostkey algorithm during an SSH connection attempt. This can occur for authorised and unauthorised SSH connection attempts.

Resolution: If this SSH connection attempt is expected and prevents an authorised person from accessing the LoadMaster, then a reboot of the LoadMaster can be performed first to clear the error. If this does not fix the issue, then running ssh -vvv <args> or a packet capture can give more details about the client's SSH connection attempt. Ensure the client and the LoadMaster is running a similar version of OpenSSH to allow the SSH connection to be established.

Packet Capture Steps on the LoadMaster:

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