In Azure, you can set up a Virtual Machine (VM) to act as a master or control machine, and then add one or more Bastion Hosts (or jump hosts) as slave machines to improve security and manage access to your VMs. This setup can help you secure access to your VMs by allowing connections only through the Bastion Hosts. Here's a step-by-step guide to achieving this:

Create the Master VM:

Log in to your Azure portal.

Click on "Create a resource" and select "Virtual Machine."

Follow the wizard to configure your master VM, including the OS, size, networking, and any additional settings.

Configure Network Security Groups (NSGs):

While creating the master VM or after, make sure to configure the NSG rules to restrict access to the VM. Typically, you'd allow SSH or RDP access from only specific IP addresses.

Create Bastion Hosts:

Create one or more VMs that will act as bastion hosts. These should be placed in a separate virtual network (VNet) or subnet.

Follow the same steps as above for creating VMs, but make sure to choose a smaller size for the bastion hosts, as they are primarily for managing access.

Configure NSGs for Bastion Hosts:

Configure NSG rules for the bastion host subnets to allow SSH (for Linux) or RDP (for Windows) access from your trusted IP addresses.

Install Bastion Host Software:

You may need to install bastion host software like OpenSSH or a third-party SSH/RDP solution on your bastion hosts.

Set Up SSH Key Authentication (Linux):

If you're using Linux VMs, ensure you have your SSH key configured on the master VM and bastion hosts for secure authentication.

Access the Master VM via Bastion:

To access the master VM, connect to one of the bastion hosts using SSH (for Linux) or RDP (for Windows) from your trusted machine.

Once connected to the bastion host, you can use SSH or RDP to connect to the master VM from there.

Optional: Configure Port Forwarding (SSH):

To simplify access, you can set up SSH port forwarding through the bastion host to connect to specific VMs behind it.

Monitoring and Logging:

Implement Azure Monitor and Azure Security Center to keep an eye on activities and security events on your VMs and bastion hosts.

Backup and Maintenance:

Regularly backup and maintain your VMs and bastion hosts to ensure their security and availability.