SSH authentication using private/public key issue

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Hi everyone. I am having issues trying to implement private/public-key SSH authentication in DataMiner. I have created a private and a public key and placed the public key on the remote Linux machine in the authorized_keys file. My private key is encrypted with the symmetric cipher 3DES in Cipher Block Chaining mode. Running the authentication from the command prompt works as expected:

PS C:\Users\EnisAB\.ssh> ssh -i dataminer_private_key.pem {username}@{ip}
Enter passphrase for key 'dataminer_private_key.pem':

Welcome to Ubuntu 24.04.2 LTS ...

The issue is that it is not working from dataminer. I have added the parameter to the connector that represents the key, and set options="ssh options" (options attribute, I have also tried with Identity element) to the parameter with value:
key=C:\Skyline Dataminer\Documents\Linux Platform\dataminer_private_key.pem;pass=myPassphrase

Authentication via DataMiner fails. I have gone through the logs in SLSsh.txt from DataMiner and the logs on the remote machine:

Relevant SLSsh logs:
2025-06-02 15:37:31 - -1 - No identity available for 'publickey' auth
2025-06-02 15:37:31 - -1 - SSH_MSG_USERAUTH_FAILURE without partial success - The password has not been changed. Either password changing was not supported, or the old password was bad.
2025-06-02 15:37:31 - -1 - Auth Canceled on connect: Tamir.SharpSsh.jsch.JSchAuthCancelException: password
at Tamir.SharpSsh.jsch.UserAuthPassword.start(Session session)
at Tamir.SharpSsh.jsch.Session.connect(Int32 connectTimeout)
2025-06-02 15:37:31 - 4 - Connect exception: Tamir.SharpSsh.jsch.JSchException: Auth cancel
at Tamir.SharpSsh.jsch.Session.connect(Int32 connectTimeout)
at Tamir.SharpSsh.jsch.Session.connect()
at Tamir.SharpSsh.SshBase.ConnectSession(Int32 tcpPort)
at Tamir.SharpSsh.SshBase.Connect(Int32 tcpPort)
at Skyline.SSH.SshConnection.Connect()
2025-06-02 15:37:31 - 4 - Connect complete (595.7201ms)
2025-06-02 15:37:31 - 4 - Set Timeout 1500
2025-06-02 15:37:31 - 4 - WriteLine exception: System.InvalidOperationException: Not Connected.
at Skyline.SSH.SshConnection.WriteLine(String data)
2025-06-02 15:37:31 - 4 - Read exception: System.InvalidOperationException: Not Connected.
at Skyline.SSH.SshConnection.Read()
...

Relevant remote linux machine logs:
2025-06-02T13:16:45.724353+00:00 slc-h73-g03 sshd[2580093]: Invalid user  from 10.11.6.48 port 53642 2025-06-02T13:16:45.726411+00:00 slc-h73-g03 sshd[2580093]: Failed none for invalid user  from 10.11.6.48 port 53642 ssh2 2025-06-02T13:16:45.732035+00:00 slc-h73-g03 sshd[2580093]: error: Received disconnect from 10.11.6.48 port 53642:3: Tamir.SharpSsh.jsch.JSchException: Auth cancel\\r\\n   at Tamir.SharpSsh.jsch.Session.connect(Int32 connectTimeout) [preauth] 2025-06-02T13:16:45.732114+00:00 slc-h73-g03 sshd[2580093]: Disconnected from invalid user  10.11.6.48 port 53642 [preauth] ...

The underlined log entry on the remote Linux machine might be telling, there are two spaces between “user” and “from,” which implies the user field is empty. That’s odd, because with public/private-key auth I’d expect the identity to be tied to the key.

If someone is interested in my private and public key format, here are the formats I used:

Private key format (.pem file):
-----BEGIN RSA PRIVATE KEY-----
Proc-Type: 4,ENCRYPTED
DEK-Info: DES-EDE3-CBC,7EE6FCEBD891256B

cEDZyvjYAjijW82VbbqHCGBhxIPuSrg77vFa5RUfDT...
-----END RSA PRIVATE KEY-----

Public key format (.pub file):
ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQC+MWBslbbM3okxAP/GyAEqJKoR0AzRl7O...

Has anyone ran into this issue?

Enis Abaza [SLC] [DevOps Advocate] Selected answer as best 3 days ago

1 Answer

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There are two suspicious log entries worth highlighting:

  1. 2025-06-02 15:37:31 - -1 - No identity available for 'publickey' auth

    This suggests that the identity file may not be properly configured. However, based on the key parameter you shared, the configuration looks correct. It's possible this message originates from a different SSH session and may not be directly related to the issue you're troubleshooting.

  2. 2025-06-02T13:16:45.724353+00:00 slc-h73-g03 sshd[2580093]: Invalid user from 10.11.6.48 port

    Good catch on the space in the log entry! This message indicates that DataMiner is attempting to authenticate without specifying a username. It's important to note that even when using a private key for authentication, DataMiner must explicitly provide a username (SSH does not infer it from the key itself). The key only proves that you have access to that particular user's account.

Correcting the username configuration should help resolve the authentication issue with the server.

Enis Abaza [SLC] [DevOps Advocate] Posted new comment 3 days ago
Enis Abaza [SLC] [DevOps Advocate] commented

Everything works as expected now, thank you very much Jeroen