Jenkins SSH server showing error Algorithm negotiation fail while trying to setup with over the SSH plugin

Question

Jenkins SSH server showing mentioned error Algorithm negotiation fail while trying to set up with over the SSH plugin when trying to connect over ssh to a local server (Linux Container). I am able to connect using ssh on the terminal.

jenkins.plugins.publish_over.BapPublisherException: Failed to connect and initialize SSH connection. Message: [Failed to connect session for config [anisbleHOST]. Message [Algorithm negotiation fail]]

Ubuntu machine - auth.log Unable to negotiate with xx.xx.xx.x port 39866: no matching host key type found. Their offer: ssh-rsa,ssh-dss,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521 [preauth]

tried with the mentioned below sshd_config values but no luck.

HostKeyAlgorithms [email protected],ssh-ed25519

KexAlgorithms [email protected],ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group14-sha1,diffie-hellman-group-exchange-sha1,diffie-hellman-group1-sha1

Answer 1

To resolve the above-mentioned issue first I made changes to /etc/ssh/sshd_config and regenerated RSA keys using ssh-keygen. Jenkins doesn't support keys generated using ed25519.

My New sshd_config -

HostKeyAlgorithms [email protected],rsa-sha2-512,rsa-sha2-256,ssh-rsa

HostKey /etc/ssh/ssh_host_key

HostKey /etc/ssh/ssh_host_rsa_key

HostCertificate /etc/ssh/ssh_host_key-cert.pub

KexAlgorithms diffie-hellman-group14-sha1,diffie-hellman-group14-sha256,diffie-hellman-group16-sha512,ecdh-sha2-nistp256,ecdh-sha2-nistp384

PubkeyAcceptedKeyTypes ssh-rsa,[email protected],[email protected],ssh-ed25519

TrustedUserCAkeys /etc/ssh/ssh_user_ca.pub

PasswordAuthentication no

ChallengeResponseAuthentication no

UsePAM yes

PrintMotd no

AcceptEnv LANG LC_*

Subsystem sftp /usr/lib/openssh/sftp-server

LogLevel DEBUG

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Please UPVOTE if it helps you :)