Hi Kwangsun Jang,
Thank you for reaching out to us on the Microsoft Q&A forum.
This error can occur for several reasons, such as incorrect SSH credentials, key pair issues, or VM configuration problems. The "Permission denied" error usually happens when trying to connect to the VM via SSH and is often due to incorrect credentials, improper SSH key configuration, or misconfigured VM settings.
To resolve this issue, ensure that the private SSH key matches the public key on the VM, or verify that the username and password are correct if using password-based authentication. Additionally, check the Network Security Group NSG rules for your VM permit port 22, which is required for SSH, to be open.
Please find the documents below for more information:
Connect using SSH to an Azure VM running Windows - Azure Virtual Machines | Microsoft Learn
https://learn.microsoft.com/en-us/azure/virtual-machines/linux/ssh-from-windows https://learn.microsoft.com/en-us/troubleshoot/azure/virtual-machines/linux/troubleshoot-ssh-connection
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