Jenkins master to slave connection is giving key verification error.

[subrat. kp]

Hi Team,

We have  set up a Master slave configuration it is giving Error as  Host Key Verification Strategy failed  and we had the  strategy i.e Non Verifying Verification Strategy , but even after that the host are offline. Please suggest what need to be done, once we Comment the KexAlgorithms and MACs these two lines in the  SSHD_Config File , the nodes are online, Please give a permanent solution for these ? 

[Ivan Fernandez Calvo]

>We have  set up a Master slave configuration it is giving Error as  Host Key Verification Strategy failed

Could you provide the error and exception stack trace you show in the logs of the AGENT? 

>and we had the  strategy i.e Non Verifying Verification Strategy , but even after that the host are offline.

I do not understand what it is the initial configuration of the Agent and what you are changing. Again, the error and stack trace can help here.

>Please suggest what need to be done, once we Comment the KexAlgorithms and MACs these two lines in the  SSHD_Config File , the nodes are online, Please give a permanent solution for these ? 

Which settings did you comment exactly? Can you provide the line you have commented?

It looks like is related to the kex process but, you do not provide info about the length and algorithm of your keys, also you do not provide the kex algorithms you have configured, so it is really difficult to help you in any way.

Check this documentation to see if you are configuring correctly the Host Key Verification and if your key is supported

https://github.com/jenkinsci/ssh-slaves-plugin/blob/master/doc/CONFIGURE.md#host-key-verification-strategy

these are the Kex algorithm supported

https://github.com/jenkinsci/trilead-ssh2/blob/f6cf3b4230a3350cfa9670c44c991d351ee184f0/src/com/trilead/ssh2/transport/KexManager.java#L374-L375