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Troubleshoot SSH access to Azure Arc enabled servers

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This article provides information on troubleshooting and resolving issues that may occur while attempting to connect to Azure Arc enabled servers via SSH. For general information, see SSH access to Arc enabled servers overview.

Important

SSH for Arc-enabled servers is currently in PREVIEW. See the Supplemental Terms of Use for Microsoft Azure Previews for legal terms that apply to Azure features that are in beta, preview, or otherwise not yet released into general availability.

Client-side issues

These issues are due to errors that occur on the machine that the user is connecting from.

Incorrect Azure subscription

This occurs when the active subscription for Azure CLI isn't the same as the server that is being connected to. Possible errors:

  • "Unable to determine the target machine type as Azure VM or Arc Server"
  • "Unable to determine that the target machine is an Arc Server"
  • "Unable to determine that the target machine is an Azure VM"
  • "The resource <name> in the resource group <resource group> was not found"

Resolution:

  • Run az account set -s <AzureSubscriptionId> where "AzureSubscriptionId" corresponds to the subscription that contains the target resource.

Unable to locate client binaries

This issue occurs when the client side SSH binaries required to connect cannot be found. Error:

  • "Failed to create ssh key file with error: <ERROR>."
  • "Failed to run ssh command with error: <ERROR>."
  • "Failed to get certificate info with error: <ERROR>."
  • "Failed to create ssh key file with error: [WinError 2] The system cannot find the file specified."
  • "Failed to create ssh key file with error: [Errno 2] No such file or directory: 'ssh-keygen'."

Resolution:

  • Provide the path to the folder that contains the SSH client executables by using the --ssh-client-folder parameter.

Server-side issues

SSH traffic is not allowed on the server

This issue occurs when SSHD isn't running on the server, or SSH traffic isn't allowed on the server. Possible errors:

  • {"level":"fatal","msg":"sshproxy: error copying information from the connection: read tcp 192.168.1.180:60887-\u003e40.122.115.96:443: wsarecv: An existing connection was forcibly closed by the remote host.","time":"2022-02-24T13:50:40-05:00"}

Resolution:

  • Ensure that the SSHD service is running on the Arc-enabled server
  • Ensure that port 22 (or other non-default port) is listed in allowed incoming connections. Run azcmagent config list on the Arc-enabled server in an elevated session

Azure permissions issues

Incorrect role assignments

This issue occurs when the current user does not have the proper role assignment on the target resource, specifically a lack of "read" permissions. Possible errors:

  • "Unable to determine the target machine type as Azure VM or Arc Server"
  • "Unable to determine that the target machine is an Arc Server"
  • "Unable to determine that the target machine is an Azure VM"
  • "Permission denied (publickey)."
  • "Request for Azure Relay Information Failed: (AuthorizationFailed) The client '<user name>' with object id '<ID>' does not have authorization to perform action 'Microsoft.HybridConnectivity/endpoints/listCredentials/action' over scope '/subscriptions/<Subscription ID>/resourceGroups/<Resource Group>/providers/Microsoft.HybridCompute/machines/<Machine Name>/providers/Microsoft.HybridConnectivity/endpoints/default' or the scope is invalid. If access was recently granted, please refresh your credentials."

Resolution:

  • Ensure that you have Contributor or Owner permissions on the resource you are connecting to.
  • If using Azure AD login, ensure you have the Virtual Machine User Login or the Virtual Machine Administrator Login roles

HybridConnectiviry RP was not registered

This issue occurs when the HybridConnectivity RP has not been registered for the subscription. Error:

  • Request for Azure Relay Information Failed: (NoRegisteredProviderFound) Code: NoRegisteredProviderFound

Resolution:

  • Run az provider register -n Microsoft.HybridConnectivity
  • Confirm success by running az provider show -n Microsoft.HybridConnectivity, verify that "registrationState" is set to "Registered"
  • Restart the hybrid agent on the Arc-enabled server

Disable SSH to Arc-enabled servers

This functionality can be disabled by completing the following actions:

  • Remove the SSH port from the allowedincoming ports: azcmagent config set incomingconnections.ports <other open ports,...>
  • Delete the default connectivity endpoint: az rest --method delete --uri https://management.azure.com/subscriptions/<subscription>/resourceGroups/<resourcegroup>/providers/Microsoft.HybridCompute/machines/<arc enabled server name>/providers/Microsoft.HybridConnectivity/endpoints/default?api-version=2021-10-06-preview