Secure Your VMs with Azure Bastion: AZ-900 Guide

Azure Bastion is a fully managed PaaS service that provides secure RDP and SSH access to virtual machines directly through the Azure portal over SSL (Port 443). By eliminating the need for public IP addresses on your VMs, it significantly reduces the attack surface and protects your virtual network from brute-force attacks.

What exactly is Azure Bastion?

Think of Azure Bastion as a highly secure, managed gateway that lets you connect to your virtual machines without exposing them to the open internet. In the old days, if you wanted to manage a VM, you'd either give it a public IP address or set up a 'jump box'—a sacrificial VM that acted as a bridge. Both methods are risky because they leave a door open for hackers to knock on.

Azure Bastion changes the game by providing a PaaS (Platform as a Service) solution. You no longer need to manage a separate jump box VM or worry about patching it. Instead, you access your VMs directly through the Azure portal using your web browser. For the AZ-900 exam, remember that Bastion is all about simplifying secure connectivity while removing the vulnerabilities associated with public-facing management ports.

How does Bastion eliminate public IP risks?

The biggest security nightmare for any cloud admin is an open RDP (Port 3389) or SSH (Port 22) port facing the public internet. If you leave these open, botnets will find them within minutes and start brute-forcing your passwords. Traditionally, the only way to connect was to assign a public IP to your VM, which effectively puts a target on its back.

With Azure Bastion, your VMs can stay completely private. They don't need public IP addresses at all. Bastion sits in a dedicated subnet (AzureBastionSubnet) and handles the connection for you. You connect to the Bastion service, and Bastion connects to your VM internally. This effectively hides your servers from the public eye, drastically reducing your attack surface and making your virtual network far more resilient to external threats.

Why is Port 443 the secret to Bastion's security?

One of the most testable concepts for the AZ-900 is how Bastion actually transmits data. Instead of using the risky RDP or SSH ports over the internet, Azure Bastion leverages SSL (Secure Sockets Layer) via Port 443. This is the same encrypted protocol used for secure web browsing (HTTPS).

When you use Bastion, your browser establishes an HTTPS connection to the Azure portal. The RDP or SSH traffic is then tunneled through that encrypted SSL connection. From the perspective of your corporate firewall, you're just visiting a website on Port 443, which is almost always allowed. This removes the need to open dangerous ports on your Network Security Groups (NSGs), ensuring that the only way into your VM is through a secure, encrypted, and authenticated channel.

How does Entra ID integration enhance access control?

Security isn't just about closing ports; it's about knowing exactly who is entering your environment. Azure Bastion integrates seamlessly with Microsoft Entra ID (formerly Azure Active Directory) to provide robust access control. Instead of relying solely on local VM credentials, you can use Role-Based Access Control (RBAC) to determine who has permission to use the Bastion service.

By leveraging Entra ID, you can enforce Multi-Factor Authentication (MFA) and Conditional Access policies. For example, you can stipulate that an admin can only access a production VM via Bastion if they are on a corporate-managed device and have passed an MFA prompt. This layered approach ensures that even if a VM password is leaked, the attacker still can't reach the VM because they can't get through the Entra ID-protected Bastion gateway.

When should you choose Bastion over a traditional Jump Box?

You might wonder why you'd pay for Bastion when you could just spin up a tiny Linux VM as a jump box for free. The answer is 'operational overhead.' A jump box is just another VM—it needs to be patched, monitored, and secured. If your jump box is compromised, your entire internal network is at risk. You're essentially trading one security hole for another.

Bastion is a managed service, meaning Microsoft handles the scaling, patching, and availability. While there is a cost associated with it, the trade-off is a massive reduction in administrative burden and a significant increase in security. For any enterprise environment or a high-stakes exam like the AZ-900, the managed approach of Bastion is the gold standard for secure remote management.

How do you master Azure Bastion for the AZ-900 exam?

The AZ-900 exam loves to test your ability to choose the right tool for a specific security scenario. You'll likely see questions asking how to reduce the attack surface of a VNet or how to connect to a VM without a public IP. When you see those keywords, your mind should immediately jump to Azure Bastion.

To truly nail these questions, you need more than just reading—you need practice. At Cert Sensei, we provide 1,000 expert-curated Microsoft Azure Fundamentals (AZ-900) practice questions. We don't just give you the answer; we provide detailed expert reasoning for every single response. Plus, our domain-level analytics will show you exactly where you're struggling—whether it's security, pricing, or core architecture—so you can stop guessing and start studying with precision.

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