You sign in by enabling Microsoft Entra-based authentication on the Linux VM and then using OpenSSH with an identity that is authorised for that machine. Access is controlled by Azure role assignment and the SSH path should not rely on shared local accounts for routine use. Verify that only approved users can authenticate and that SSH login attempts are audited.
How the Entra ID sign-in flow works with OpenSSH
The practical pattern is to make the VM trust Microsoft Entra-based authentication, then use OpenSSH as the client path. That means the user’s approved Entra identity is the control point, while SSH remains the transport and command channel. The important design choice is that access comes from the cloud identity and Azure role assignment, not from a shared local password or ad hoc local admin use.
Once configured, the sign-in path is still ordinary SSH from the user’s perspective: the client connects to the VM, the platform checks whether that identity is allowed, and the session is established only if the user has the right Azure permissions. In other words, the Linux VM does not become “passwordless by default”; it becomes identity-governed, with role assignment determining who is allowed to complete the login.
For teams that already manage SSH keys and certificates, the operational question is whether Entra-based login is replacing, supplementing, or constraining the existing SSH trust model. If the VM still accepts unmanaged local users or long-lived keys, Entra ID may improve governance but not remove the older exposure paths. The sign-in model is strongest when the approved login path is the one routinely used and all other access paths are treated as exceptions.
What must be true for the login to succeed
Three conditions matter most: the VM must have Microsoft Entra authentication enabled, the user must be assigned access through Azure, and the SSH client must use a valid path to that machine. If any of those pieces is missing, the login fails for the right reason, because the platform cannot establish that the requester is authorised for that VM.
This also means you should verify the permission boundary before you test the SSH command. A user may be signed into the right Entra tenant but still be blocked if the Azure role assignment is missing or too narrow. Conversely, a user with a broad role may be able to connect even if the local Linux account strategy is inconsistent, which is why the role model and the guest account model need to be reviewed together.
In practice, the cleanest setup is the one where the Entra-based login path is the default and the Linux account layer is only used for break-glass or tightly controlled administrative exceptions. That keeps the approval decision at the Azure layer, where you can review and revoke it centrally rather than chasing local account drift across many VMs.
What to validate before you trust the setup
Validate that only approved users can authenticate, that role assignment is the gating control, and that the VM records the login attempt in audit logs. The sign-in method is only useful if you can prove who connected, from where, and under what permission set. Without that evidence, you have identity-based access in theory but weak operational assurance in practice.
It is also worth checking whether the approved path still allows routine SSH access without reintroducing shared local accounts. Shared accounts make attribution weak and create a second access path that bypasses the governance model you just put in place. If you need local accounts for recovery, keep them exceptional, documented, and monitored.
For broader identity hardening, the same control logic used for privileged access and role assignment still applies here: Active Directory and Entra ID Hardening Guide is the right companion when you are deciding how much trust to place in Entra roles, privileged groups, and delegated access.
Risk and Threat Considerations
The main risk is not the SSH protocol itself, but the access path around it. If local accounts, broad Azure roles, or unmanaged keys remain available, an attacker who gains one of those credentials can still reach the VM even when Entra login is enabled. The control only reduces exposure when the Entra-authenticated path is the one that actually governs access.
Failure mechanism: A mis-scoped role assignment, stale local account, or exposed SSH key can bypass the intended Entra control and allow unauthorised login to the VM.
Impact: The result can be unauthorised shell access, lateral movement from the VM, or persistence through an access path that operators believe is centrally governed.
Standards & Framework Alignment
This section maps relevant standards and security frameworks to the operational risks and controls described in this guidance.
OWASP Non-Human Identity Top 10 addresses the attack and risk surface, while NIST SP 800-53 Rev 5 and NIST CSF 2.0 set the governance and control requirements practitioners need to meet.
| Framework | Control / Reference | Relevance |
|---|---|---|
| NIST SP 800-53 Rev 5 | IA-2 — Identification and Authentication (Organizational Users) | Entra-backed VM sign-in hinges on authenticating approved human users. |
| IA-5 — Authenticator Management | SSH access depends on managing credentials, keys, and authentication material over time. | |
| AU-2 — Audit Events | The page explicitly relies on logging SSH login attempts for accountability. | |
| Recommendation — Use IA-2 to require strong authentication before VM SSH access is granted. Use IA-5 to control lifecycle, rotation, and protection of SSH-related authenticators. Configure AU-2 to log VM authentication and SSH access events. | ||
| OWASP Non-Human Identity Top 10 | NHI-04 — Insecure Authentication | Entra-governed SSH access is an authentication path for a non-human host or service context. |
| NHI-05 — Overprivileged NHI | Azure role assignment determines who can log in, so excess privilege directly changes exposure. | |
| Recommendation — Enforce NHI-04 to prevent weak or bypassable authentication paths for the VM. Apply NHI-05 to keep VM login roles narrowly scoped and reviewable. | ||
| NIST CSF 2.0 | PR.AA-05 — Identities and Access Permissions | The answer centers on approved identities and Azure role assignment for access control. |
| DE.CM-08 — Vulnerability Scans are Performed | Operational assurance depends on checking the VM configuration and login exposure over time. | |
| Recommendation — Use PR.AA-05 to verify only authorised identities can establish SSH sessions. Use DE.CM-08 to monitor the VM estate for drift and exposed access paths. | ||
Practitioner Guidance
What to verify: Confirm that the effective access decision is made in Azure, not by a leftover local account or an orphaned key on the guest OS. If you can still log in through an unmanaged path, the deployment is not yet in its desired state.
Common mistake: Teams enable Entra-based login but leave broad administrative roles in place, so the environment still behaves like shared-admin SSH with better branding. Tighten the role assignment model before declaring the migration complete.
Practitioner takeaway: Treat Entra ID as the authoritative approval layer and SSH as the transport, then audit for every alternate login path that could undermine that decision.
Related resources from NHI Mgmt Group
- Guide: SSH Key and SSH Certificate Management Guide
- How do you investigate AI agent sign-ins in Microsoft Entra Agent ID?
- How do you block risky sign-ins with Conditional Access in Microsoft Entra ID?
- How do you block sign-ins from specific countries with Conditional Access in Microsoft Entra ID?
- How do you collect and analyse Microsoft Entra ID sign-in and audit logs?