Guidance for secure remote VM management in Azure using Azure Bastion combined with Defender for Cloud just-in-time (JIT) VM access. Covers Bastion SKU selection (Developer / Basic / Standard / Premium), IP-based and shareable-link connections, native client (RDP/SSH from local machine via az CLI), session recording (Premium), private-only deployment, JIT request workflow and policy, RBAC for connect operations, integration with Conditional Access (via Bastion + Entra login on the VM), Azure Policy enforcement to require Bastion + JIT and prohibit public IP on VMs, and migration off VPN/jump-box patterns. WHEN: Azure Bastion design, Bastion SKU comparison, JIT VM access, just-in-time access Azure, Bastion shareable link, native client Bastion, session recording Bastion, eliminate public IP on VMs, replace jump host with Bastion, secure RDP SSH Azure, Bastion Premium recording. DO NOT USE for hybrid/SD-WAN VPN design, GSA Private Access (use entra-global-secure-access), or cluster-only K8s access.
インストール
Codex または Claude でインストール この Prompt をコピーして Codex、Claude、または他のアシスタントに貼り付けると、Skill ページを確認してインストールできます。
Guidance for secure remote VM management in Azure using Azure Bastion combined with Defender for Cloud just-in-time (JIT) VM access. Covers Bastion SKU selection (Developer / Basic / Standard / Premium), IP-based and shareable-link connections, native client (RDP/SSH from local machine via az CLI), session recording (Premium), private-only deployment, JIT request workflow and policy, RBAC for connect operations, integration with Conditional Access (via Bastion + Entra login on the VM), Azure Policy enforcement to require Bastion + JIT and prohibit public IP on VMs, and migration off VPN/jump-box patterns. WHEN: Azure Bastion design, Bastion SKU comparison, JIT VM access, just-in-time access Azure, Bastion shareable link, native client Bastion, session recording Bastion, eliminate public IP on VMs, replace jump host with Bastion, secure RDP SSH Azure, Bastion Premium recording. DO NOT USE for hybrid/SD-WAN VPN design, GSA Private Access (use entra-global-secure-access), or cluster-only K8s access.
license
MIT
metadata
{"author":"Microsoft","version":"0.1.0"}
Azure Bastion + Just-In-Time VM Access
The combination of Azure Bastion (managed, browser/native-client jump service) and
Defender for Cloud just-in-time (JIT) VM access (time-limited NSG allow-rules for
management ports) eliminates the two most common Azure VM compromise paths:
internet-exposed RDP/SSH and standing-open management ports.
When to use
Designing or hardening administrative access to Azure IaaS VMs and VMSS. Use this skill
for SKU selection, JIT policy, public-IP elimination, and the operational workflow.
Do not use this skill for hybrid VPN/SD-WAN design, ZTNA replacement of VPN
(entra-global-secure-access), or AKS-only access.
Bastion SKUs — pick by feature need
SKU
Capabilities
Developer
Free, ad-hoc, browser-only RDP/SSH to a single VM, single VNet, no scale, no shareable links
Basic
RDP/SSH via portal, private-IP-only VMs supported, single-instance scale
Standard
+ Native client, shareable links, IP-based connection, Kerberos, Linux file copy, custom port, scale up to 50 instances
Premium
+ Session recording, private-only deployment, additional admin features
Rule of thumb: Standard for most enterprise; Premium where session recording or
private-only deployment is required (regulated industries). Developer is for
non-production / sandbox personal use.
Approach
Architecture. One Bastion per hub VNet (or per spoke if traffic isolation
requires). Required subnet: AzureBastionSubnet /26 minimum. NSG on the subnet
follows the documented allow rules — don't write "deny all from internet" without
the documented allow exceptions or Bastion breaks.
Eliminate VM public IPs. Azure Policy: Public IP addresses should not be
associated with virtual machines — set to Deny in production scopes. New VMs are
private-only; admin access is via Bastion + JIT.
Bastion + Entra login on the VM. Combine with Microsoft Entra login for Windows/Linux VM extension so RDP/SSH authenticates with Entra credentials,
honoring Conditional Access (MFA, device compliance, named locations) on the VM
sign-in itself. This is the missing leg most "Bastion-only" deployments forget.
Configure JIT for every VM that's allowed RDP/SSH.
Default ports: RDP 3389, SSH 22, WinRM 5985/5986.
Max request window: 3 hours.
Source: Requestor's IP (or Bastion subnet, since requests come from there).
Approval: implicit by RBAC, or add a manual approval step for tier-0 VMs.
RBAC on Bastion connect. Bastion connect is not the same as VM RBAC. Required
roles:
Reader on the Bastion + the VM + its NIC + its VNet.
Virtual Machine User Login (Linux) / Virtual Machine Administrator Login
for Entra-based VM sign-in.
JIT request: Microsoft.Security/locations/jitNetworkAccessPolicies/initiate/action.
Bake into a custom role per persona to avoid over-granting.
Native client (az network bastion rdp/ssh): admins use local mstsc/SSH
tooling; better UX than browser tab. CA still applies via VM sign-in.
IP-based connection: Bastion to peered on-prem VMs over ExpressRoute/VPN.
Shareable links: time-bound URL for break-glass to a contractor. Disable
unless explicitly needed; audit usage.
Session recording (Premium). Records video of administrator sessions to a Log
Analytics workspace / Storage. Required for some regulated industries; review
retention and access controls.
JIT request workflow. Document for admins:
Open Defender for Cloud → JIT VM access → Request access → port + window.
Connect via Bastion within window.
NSG rules auto-revert on expiry.
Monitor. Stream Bastion diagnostic logs (BastionAuditLogs) and JIT
activity-log events to Sentinel. Detect: requests outside business hours from
unexpected IPs, rapid sequential VMs by one principal.
Guardrails
Don't write a deny-all NSG on the AzureBastionSubnet. It must allow specific
service tags / ports; the documented rules are required for the service to work.
JIT changes NSG rules, not Azure Firewall / NVA rules. If management traffic
flows through a firewall, JIT alone won't open it. Either layer firewall policy or
route management traffic via Bastion only.
Bastion alone is not Conditional Access. Without Entra login on the VM, you've
removed public exposure but a stolen VM credential still works. Combine.
Shareable links bypass MFA on the originating user unless paired with Entra VM
login. Avoid for sensitive VMs.
Premium session recording is a heavy storage commitment. Plan retention and
cost.
Don't deploy Bastion in every spoke VNet "for convenience." One per hub with
peering is usually right; the per-instance cost adds up.
JIT request from a shared NAT IP opens the port for everyone behind that NAT
during the window. Combine with named locations and CA.
Public IP on a VM and Bastion peer access "as backup" — defeats the model. Pick
one path.
Common anti-patterns
"Bastion + public IP on VMs left in place 'just for break-glass'" — break-glass
is a procedure, not an unmonitored open RDP port.
"JIT request window = 8 hours, source = any" — that's an open port for a working
day from the internet.
"Bastion without Entra VM login" — local admin password compromise is still
game-over.
"Shareable links shared by email forever" — turn into permanent backdoors. Time-
bound + audit.
"Recorded all sessions to a workspace anyone can read" — recording reveals
privileged actions and credentials.
"Standalone Bastion per dev VM" — uneconomical and noisy. One per hub.
"Skipped Sentinel/log integration" — Bastion sessions invisible to SOC.
"Used Bastion for AKS API server access" — wrong tool; use private cluster + GSA
Private Access or jumpbox + kube-config.
Example prompts
Design Bastion + JIT for a 3-hub multi-region landing zone with a 2,000-VM estate.
Migrate from a self-managed Windows jump host to Bastion + Entra VM login + JIT.
Eliminate public IP on Linux VMs via Azure Policy and roll out private-only access.
Configure session recording on Bastion Premium with 1-year retention to Storage.
Build a custom RBAC role for "VM Operator via Bastion" combining Bastion connect + Entra login + JIT request only.
Sentinel detections: JIT request out-of-hours, rapid sequential VM access by one principal, shareable link creation.
Compare Bastion shareable link vs Entra Private Access for occasional contractor access.
