Virtual Machines 101: What They Are and How to Use Them Securely

At its core, a virtual machine (VM) is a software-based emulation of a physical computer. It creates a virtual environment that runs its own operating system (OS) and applications independently from your primary hardware (often referred to as the “host” machine). 

Think of a VM as a sandbox. It’s self-contained, which means everything is inside it, including the OS, the files, and apps which are separated from the host computer. 

How does it differ from a physical machine? 

The main difference comes down to tangibility. A physical machine (like your laptop, desktop, or server) is hardware-dependent. A VM, on the other hand, is software-defined and runs on a physical machine but functions as independent hardware. 

Here are some key differences to note:

• Flexibility: VMs can run multiple operating systems on a single physical machine.

• Isolation: They operate in a confined virtual environment, so if configured properly, errors or viruses inside a VM don’t affect the host.

• Immobility (Physical Machine): A physical machine can’t be moved or cloned, unlike VMs, which can be replicated and migrated easily.

Benefits of using virtual machines 

Virtual machines bring a ton of value to the table, including:

• Testing & experimentation: Developers can test new code or software in a safe, isolated environment without risking their primary system.

• Cost efficiency: VMs allow multiple “computers” to run on a single physical machine, reducing hardware and maintenance costs.

• Disaster recovery: Virtual machines can be backed up and restored easily.

• Cross-platform compatibility: You can run Windows on a Mac or Linux on Windows with VMs.

Drawbacks of using virtual machines 

Like any tool, VMs aren’t without limitations:

• Performance overhead: VMs rely on the host machine’s resources, which can cause slower performance if overutilized.

• Complex setup: Setting up VMs can be challenging, especially for beginners unfamiliar with virtualization software or resource allocation.

• Security risks: While isolated, poorly configured VMs can still be vulnerable to threats, especially if connected to a network.

Setting up and configuring a virtual machine 

Step 1: Choose your virtualization software 

To get started with VMs, you'll need virtualization software. Some popular options include:

• VMware (for advanced configuration and enterprise-level use)

• VirtualBox (free and beginner-friendly)

• Microsoft Hyper-V (ideal for Windows users)

Step 2: Create your virtual machine 

1. Install your chosen virtualization software.

2. Choose the operating system (e.g., Windows, Linux, macOS) you want to run on the VM.

3. Follow your software's guided setup to configure storage, memory, and CPU.

Step 3: Allocate resources 

Allocating resources depends on what you’ll be doing inside the VM. Here’s a general rule of thumb:

• RAM: Allocate at least 4GB for standard use, or more for resource-heavy applications.

• CPU Cores: Assign at least 2 cores for a smoother experience.

• Disk Space: Allocate 20GB or more, depending on your software and files.

Step 4: Running Multiple VMs 

Yes, you can run multiple VMs simultaneously, but this is resource-intensive. Ensure your host machine has sufficient CPU and RAM to avoid throttling. 

Networking and security for virtual machines 

Networking between VMs is generally configured through the virtualization software:

• Bridged mode: Connects VMs directly to your network, granting them individual IPs.

• NAT mode: Uses the host’s IP address for connections but isolates VMs from external access.

Can a VM get viruses? 

Absolutely. A VM functions like any other computer, so it can be infected with viruses if exposed to malicious files or websites. However, the good news is that virus activity is contained within the VM and doesn’t usually harm the host machine in most cases. 

Tips for securing virtual machines 

• Use snapshots: Take periodic snapshots of your VM so you can revert to a clean state if needed.

• Follow basic cyber hygiene: Install antivirus software, enable firewalls, and keep your VM OS updated. If you don’t already have a security hygiene plan in place, we recommend you view this blog here. 

• Isolate Critical VMs: Avoid networking VMs unnecessarily to reduce exposure to threats.