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Manage SSH access for domain accounts in Azure HDInsight

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On secure clusters, by default, all domain users in Microsoft Entra Domain Services are allowed to SSH into the head and edge nodes. These users are not part of the sudoers group and do not get root access. The SSH user created during cluster creation has root access.

Manage access

To modify SSH access to specific users or groups, update /etc/ssh/sshd_config on each of the nodes.

  1. Use ssh command to connect to your cluster. Edit the following command by replacing CLUSTERNAME with the name of your cluster, and then enter the command:

    ssh sshuser@CLUSTERNAME-ssh.azurehdinsight.net

  2. Open the ssh_config file.

    sudo nano /etc/ssh/sshd_config

  3. Modify the sshd_config file as desired. If you restrict users to certain groups, then the local accounts cannot SSH into that node. The following command is only an example of syntax:

    AllowUsers useralias1 useralias2

AllowGroups groupname1 groupname2

    Then save changes: Ctrl + X, Y, Enter.

  4. Restart sshd.

    sudo systemctl restart sshd

  5. Repeat above steps for each node.

SSH authentication log

SSH authentication log is written into /var/log/auth.log. If you see any login failures through SSH for local or domain accounts, you need to go through the log to debug the errors. Often the issue might be related to specific user accounts and it's usually a good practice to try other user accounts or SSH using the default SSH user (local account) and then attempt a kinit.

SSH debug log

To enable verbose logging, you need to restart sshd with the -d option. Like /usr/sbin/sshd -d You can also run sshd at a custom port (like 2222) so that you don't have to stop the main SSH daemon. You can also use -v option with the SSH client to get more logs (client side view of the failures).

Next steps