What is Azure Bastion?

Azure Bastion is a service you deploy that lets you connect to a virtual machine using your browser and the Azure portal, or via the native SSH or RDP client already installed on your local computer. The Azure Bastion service is a fully platform-managed PaaS service that you provision inside your virtual network. It provides secure and seamless RDP/SSH connectivity to your virtual machines directly from the Azure portal over TLS. When you connect via Azure Bastion, your virtual machines don't need a public IP address, agent, or special client software.

Bastion provides secure RDP and SSH connectivity to all of the VMs in the virtual network in which it is provisioned. Using Azure Bastion protects your virtual machines from exposing RDP/SSH ports to the outside world, while still providing secure access using RDP/SSH.

Diagram showing Azure Bastion architecture.

Key benefits

Benefit Description
RDP and SSH through the Azure portal You can get to the RDP and SSH session directly in the Azure portal using a single-click seamless experience.
Remote Session over TLS and firewall traversal for RDP/SSH Azure Bastion uses an HTML5 based web client that is automatically streamed to your local device. Your RDP/SSH session is over TLS on port 443. This enables the traffic to traverse firewalls more securely.
No Public IP address required on the Azure VM Azure Bastion opens the RDP/SSH connection to your Azure VM by using the private IP address on your VM. You don't need a public IP address on your virtual machine.
No hassle of managing Network Security Groups (NSGs) You don't need to apply any NSGs to the Azure Bastion subnet. Because Azure Bastion connects to your virtual machines over private IP, you can configure your NSGs to allow RDP/SSH from Azure Bastion only. This removes the hassle of managing NSGs each time you need to securely connect to your virtual machines. For more information about NSGs, see Network Security Groups.
No need to manage a separate bastion host on a VM Azure Bastion is a fully managed platform PaaS service from Azure that is hardened internally to provide you secure RDP/SSH connectivity.
Protection against port scanning Your VMs are protected against port scanning by rogue and malicious users because you don't need to expose the VMs to the internet.
Hardening in one place only Azure Bastion sits at the perimeter of your virtual network, so you don’t need to worry about hardening each of the VMs in your virtual network.
Protection against zero-day exploits The Azure platform protects against zero-day exploits by keeping the Azure Bastion hardened and always up to date for you.

SKUs

Azure Bastion has two available SKUs, Basic and Standard. For more information, including how to upgrade a SKU, see the Configuration settings article.

The following table shows features and corresponding SKUs.

Feature Basic SKU Standard SKU
Connect to target VMs in peered virtual networks Yes Yes
Access Linux VM Private Keys in Azure Key Vault (AKV) Yes Yes
Connect to Linux VM using SSH Yes Yes
Connect to Windows VM using RDP Yes Yes
Kerberos authentication Yes Yes
VM audio output Yes Yes
Shareable link No Yes
Connect to VMs using a native client No Yes
Connect to VMs via IP address No Yes
Host scaling No Yes
Specify custom inbound port No Yes
Connect to Linux VM using RDP No Yes
Connect to Windows VM using SSH No Yes
Upload or download files No Yes
Disable copy/paste (web-based clients) No Yes

Architecture

Azure Bastion is deployed to a virtual network and supports virtual network peering. Specifically, Azure Bastion manages RDP/SSH connectivity to VMs created in the local or peered virtual networks.

RDP and SSH are some of the fundamental means through which you can connect to your workloads running in Azure. Exposing RDP/SSH ports over the Internet isn't desired and is seen as a significant threat surface. This is often due to protocol vulnerabilities. To contain this threat surface, you can deploy bastion hosts (also known as jump-servers) at the public side of your perimeter network. Bastion host servers are designed and configured to withstand attacks. Bastion servers also provide RDP and SSH connectivity to the workloads sitting behind the bastion, as well as further inside the network.

Currently, by default, new Bastion deployments don't support zone redundancies. Previously deployed bastions may or may not be zone-redundant. The exceptions are Bastion deployments in Korea Central and Southeast Asia, which do support zone redundancies.

Diagram showing the Azure Bastion architecture.

This figure shows the architecture of an Azure Bastion deployment. In this diagram:

  • The Bastion host is deployed in the virtual network that contains the AzureBastionSubnet subnet that has a minimum /26 prefix.
  • The user connects to the Azure portal using any HTML5 browser.
  • The user selects the virtual machine to connect to.
  • With a single click, the RDP/SSH session opens in the browser.
  • No public IP is required on the Azure VM.

Host scaling

Azure Bastion supports manual host scaling. You can configure the number of host instances (scale units) in order to manage the number of concurrent RDP/SSH connections that Azure Bastion can support. Increasing the number of host instances lets Azure Bastion manage more concurrent sessions. Decreasing the number of instances decreases the number of concurrent supported sessions. Azure Bastion supports up to 50 host instances. This feature is available for the Azure Bastion Standard SKU only.

For more information, see the Configuration settings article.

Pricing

Azure Bastion pricing is a combination of hourly pricing based on SKU and instances (scale units), plus data transfer rates. Hourly pricing starts from the moment Bastion is deployed, regardless of outbound data usage. For the latest pricing information, see the Azure Bastion pricing page.

What's new?

Subscribe to the RSS feed and view the latest Azure Bastion feature updates on the Azure Updates page.

Bastion FAQ

For frequently asked questions, see the Bastion FAQ.

Next steps