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VPCs for Dummies

January 18, 2024
Written by
Ganga Sumanth

Businesses, apps and websites—all run smoothly on the internet. Ever wondered how? In today's blog we'll talk all about Virtual Private Clouds, VPCs for short. 

A VPC is a logically isolated section of a cloud service provider's infrastructure that allows users to deploy resources in a virtual network. But let's start with the basics – what comprises a VPC, and how does it function to facilitate secure and efficient digital connections?

Table of Contents

1. What is Virtual Private Cloud?

2. Anatomy of a VPC

  • CIDR Blocks
  • Subnets
  • Routing Tables
  • Internet Gateway
  • Security Groups
  • Network ACLs (Access Control Lists)
  • Elastic Load Balancer (ELB)
  • Virtual Private Network (VPN) Connections

3. Let’s talk more about subnets!

4. How to create and manage subnets

5. What's next? Unlocking your potential!

What is Virtual Private Cloud?

A Virtual Private Cloud (VPC) is a fundamental building block in cloud computing that provides a private and isolated space within the public cloud infrastructure. It's your own slice of the internet where you can deploy and manage your resources, such as virtual servers, databases, and applications, away from the public eye. Here’s why you need VPCs:

Security and Isolation

  • Controlled Access. A VPC allows users to control who can access resources, providing a secure environment that keeps your data safe from potential external threats.
  • Isolated Environment. By creating a private space, a VPC ensures that operations are isolated from other users on the cloud, thus minimizing the risk of unauthorized access or interference.

Customized Networking

  • Tailored Architecture. VPCs will give you the capability to design network architecture based on your specific needs. You can set up subnets, define IP address ranges, and configure routing tables to suit your unique requirements.
  • Network Segmentation. Segmenting your network within a VPC helps for better organization and management of resources to enhance security and makes it easier to implement specific network policies.

Scalability and Flexibility

  • Elasticity. VPCs are designed to scale seamlessly with your business. Whether you're experiencing growth or need to adapt to changing demands, a VPC provides the flexibility to adjust your network without disruptions.
  • Resource Optimization. With a VPC, you have control over resource allocation to guarantee efficient utilization and cost-effective scaling based on your workload.

Anatomy of a VPC

To truly understand the functionality and potential of a Virtual Private Cloud (VPC), let's take a look at the key components:

CIDR Blocks

The Classless Inter-Domain Routing (CIDR) block is like the postal code for your VPC, defining its address range. It's crucial to set this up thoughtfully, as it determines the total number of available IP addresses within your virtual space.


Think of subnets as neighborhoods within your VPC. They help organize resources to help you to allocate different subnets for specific purposes, such as separating development and production environments or enhancing security by isolating sensitive data.

Routing Tables

Routing tables direct the traffic within your VPC. They determine where data goes and help it navigate through the various subnets to ensure secure and efficient communication between resources.

Internet Gateway

An Internet Gateway connects your VPC to the internet. It facilitates communication between your VPC and external networks that allows resources within the VPC to access the internet and vice versa.

Security Groups

Security Groups are like virtual firewalls for your resources. They define rules for inbound and outbound traffic to make sure that only authorized communication occurs. Each resource within the VPC is associated with a specific security group.

Network ACLs (Access Control Lists)

Network ACLs provide an additional layer of control over traffic flow at the subnet level. They operate at the network level and help in setting rules to control inbound and outbound traffic.

Elastic Load Balancer (ELB)

If your VPC hosts multiple instances of an application, an Elastic Load Balancer helps distribute incoming traffic across these instances to guarantee optimal resource utilization and prevent overload on any single instance.

Virtual Private Network (VPN) Connections

VPN connections establish secure communication channels between your VPC and on-premises networks. This is particularly useful for businesses that need to extend their existing network infrastructure into the cloud.

Let’s talk more about subnets!

Subnets are the foundational building blocks that contribute to the structure and efficiency of your digital environment. Subnets, short for sub-networks, are logical partitions within your VPC that enable the segmentation of your network into smaller, manageable units. They are often described as neighborhoods within your VPC, each serving a specific purpose or hosting particular resources.

So why do they matter?

  • Subnets provide a structured way to organize your resources. You can allocate different subnets for specific functions, such as separating web servers from databases or isolating development environments.
  • By placing resources in separate subnets, you can control access and communication between them. This enhances security by minimizing the potential impact of security breaches or unauthorized access.
  • Subnet design can optimize performance by strategically placing resources closer to each other to reduce latency and improve data transfer speeds.
  • Subnets help manage IP addresses efficiently. Each subnet operates within a specific CIDR block for precise control over IP address allocation and usage.

How to create and manage subnets

Creating and managing subnets is a straightforward process within your cloud provider's console. Here's a general guide:

  1. Log in to your cloud provider's console where you manage your VPC.
  2. Locate the VPC dashboard, where you can access and manage your VPC settings.
  3. Look for the option to create or manage subnets within the VPC section.
  4. Follow the prompts to create a new subnet. You'll need to specify details such as the VPC to which it belongs, the availability zone, and the CIDR block for the subnet.
  5. Adjust any additional attributes, such as route tables, security groups, or Network ACLs associated with the subnet.
  6. Create additional subnets as necessary for your application or workload requirements.

Remember to consider factors like IP address range, resource placement, and security requirements when creating subnets. Regularly review and update your subnet configurations as your application evolves to ensure optimal performance and security.

What's next? Unlocking your potential!

This blog only scratched the surface of what VPCs can do. There's more coming, so wait for more blogs about VPCs!

When it comes to the information security job market, cloud security is one of the fastest growing. This is because most big corporations have migrated to the cloud already, and they all need the workforce to ensure that the information stored in the cloud is protected against malicious actors. 

AppSecEngineer takes cloud security seriously. We have dedicated learning paths for the three biggest cloud providers in the market: AWS, Azure, and Google Cloud Platform. Each learning path comes with meticulously structured courses, labs, playgrounds, and more. Check out our website to start!

Source for article
Ganga Sumanth

Ganga Sumanth

Ganga Sumanth is an Associate Security Engineer at we45. His natural curiosity finds him diving into various rabbit holes which he then turns into playgrounds and challenges at AppSecEngineer. A passionate speaker and a ready teacher, he takes to various platforms to speak about security vulnerabilities and hardening practices. As an active member of communities like Null and OWASP, he aspires to learn and grow in a giving environment. These days he can be found tinkering with the likes of Go and Rust and their applicability in cloud applications. When not researching the latest security exploits and patches, he's probably raving about some niche add-on to his ever-growing collection of hobbies: Long distance cycling, hobby electronics, gaming, badminton, football, high altitude trekking.

Ganga Sumanth


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