How to fix lost SSH access to Azure Linux VM after yum update?

Burzynski, Christopher 0

After running yum update on Linux Azure VM I am no longer able to access the instance via SSH. On the serial console, the VM is constantly dumping out error logs so I can't type the password fast enough. Any idea how I can gain access?

Sai Krishna Katakam 810 Reputation points Microsoft Vendor

2024-10-08T06:55:02.08+00:00

Hi Burzynski, Christopher,

Welcome to the Microsoft Q&A Platform! Thank you for asking your question here.

We are looking into this issue and will get back you soon.
Sai Krishna Katakam 810 Reputation points Microsoft Vendor

2024-10-08T07:27:40.5666667+00:00
Hi Burzynski, Christopher,

If you've lost SSH access to your Azure Linux VM after running a yum update, there are a few ways to regain access and troubleshoot the issue.

Use the Azure Serial Console:
The Azure Serial Console allows you to interact directly with the VM even when SSH is unavailable.
Navigate to your VM in the Azure portal>Under Support + troubleshooting>select Serial console>Press Enter to access the login prompt.

Reset SSH Configuration:
You can use the Run Command feature in the Azure portal to restart SSH or restore its default configuration.
In the Azure portal, navigate to your VM.
Under Operations, select Run Command and choose RunShellScript.
Run the following commands to restart SSH:

sudo systemctl restart sshd

Azure CLI:
Open Azure CLI and run the following command:

az vm run-command invoke --command-id RunShellScript --name <VMName> --resource-group <ResourceGroupName> --scripts "sudo systemctl restart sshd"

Check Network Security Group (NSG) Rules:
Make sure that the NSG rules allow SSH traffic (TCP port 22).
In the Azure portal, navigate to Networking under your VM and verify the inbound security rules.

Restore from Backup or Snapshot (if available):
If you've set up backups or snapshots, you can restore the VM to a previous state before the yum update to regain access.

For more details on troubleshooting SSH access issues, refer to the documentation: Troubleshoot SSH connections to an Azure Linux VM that fails, errors out, or is refused

If you have any further queries, do let us know. If the comment is helpful, please click "Upvote".
Sai Krishna Katakam 810 Reputation points Microsoft Vendor

2024-10-09T09:36:58.9433333+00:00

Hi Burzynski, Christopher,

Just checking in to see if you had a chance to review my comment on your question. Please let us know if it was helpful and feel free to reach out if you have any further queries.

If you found the information useful, please click "Upvote" on the post to let us know.

Thank You.
Burzynski, Christopher 0 Reputation points

2024-10-09T19:57:32.55+00:00

Sai, thank you for replying so quickly.
From the Azure serial console I can't seem to login as there are too many errors scrolling through the screen, don't have enough time to enter username and password. I power cycled the server and still the same.
I also tried the restore option but that didn't work, the issue was there for over 30 days.
Sai Krishna Katakam 810 Reputation points Microsoft Vendor

2024-10-14T04:44:04.93+00:00

Hi Burzynski, Christopher,

Just checking in to see if you had a chance to review my comment on your question. Please let us know if it was helpful and feel free to reach out if you have any further queries.

If you found the information useful, please click "Upvote" on the post to let us know.

Thank You.

1 answer

Sai Krishna Katakam 810 Reputation points Microsoft Vendor

2024-10-10T08:37:49.2466667+00:00
Hi Burzynski, Christopher,

It sounds like you’re experiencing a challenging issue with the Azure Serial Console. Here are some steps you can try to resolve it:

Ensure that boot diagnostics are enabled for your VM. This is crucial for the serial console to function properly.

Make sure your VM is in a running state and not stopped or deallocated.

If you receive a “Web socket is closed or could not be opened” error, add *.serialconsole.azure.com to your firewall allow list. Details can be found here.

Verify that you have the necessary permissions (at least Virtual Machine Contributor role) to access the serial console.

Ensure that the storage account used for boot diagnostics has not been deleted and is accessible.

For more details, please refer below documents:
Common errors within the Azure Serial Console
Azure Serial Console for Windows
How can I fix this Serial Console Problem?

If you have any further queries, do let us know. If the comment is helpful, please click "Upvote".
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