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UnprocessableEntityError: SSH Connection Error: Encountered RSA Key, Expected OPENSSH Key

Symptom​

When you register a Linux system through the API, the registration returns the following error:

{
    "name": "UnprocessableEntityError",
    "message": "SSH connection error: encountered RSA key, expected OPENSSH key",
    "code": 9999
}

Cause​

One of the following causes applies:

  1. SSH access is limited to specific accounts. For example, the /etc/ssh/sshd_config file specifies the AllowUsers or AllowGroups option.
  2. The system was already registered in Netwrix Privilege Secure for Discovery, and a user was removed from the system. This applies even if the user was added back manually.
  3. The system runs Ubuntu 22.04 or later, which does not allow RSA SSH keys by default.

Resolution​

Allow SSH Access for the Service Account​

Either change the configuration to allow SSH access for all users, or add the service account to the relevant AllowUsers or AllowGroups lines. The default service account name is secureone. Then restart the sshd service.

Remove the User and the Database Record​

IMPORTANT: This procedure deletes data from the product database. Back up the database before you continue, and confirm the system name before you run the delete command.

  1. Remove the user and the home directory from the system:

    sudo deluser --remove-home secureone

  2. If the user was removed but the home directory remains, remove the home directory manually:

    sudo rm -r /home/secureone

  3. Connect to a node over SSH, and open the database shell:

    • For a cluster deployment, run s1 db.
    • For a single-node deployment, run s1 --single-node db.

  4. Find the system records. In this example, linux01 is the system name:

    db.ldap_store.find({ "cn" : "linux01" }).count()

  5. Remove all ldap_store records of the system:

    db.ldap_store.deleteMany({ "cn" : "linux01" })

Allow RSA Keys on Ubuntu 22.04 or Later​

  1. Add the following line to the bottom of the /etc/ssh/sshd_config file:

    PubkeyAcceptedKeyTypes +ssh-rsa

  2. Restart sshd:

    sudo systemctl restart sshd