Practical guide to AWS VPC Configuration — Decoding DevOps [10]

Bhavyansh @ DiversePixel
5 min readJun 29, 2024



Amazon Virtual Private Cloud (VPC) is a foundational element in AWS, offering a secure and isolated environment for your applications. With VPC, you can have your own private network within AWS, giving you complete control over network configuration, security settings, and connectivity. This guide will take you through the essentials of setting up and managing a VPC, ensuring a robust, secure, and scalable cloud infrastructure.

Photo by Kirill Sh on Unsplash

Understanding the Fundamentals

To effectively work with AWS VPC, it’s crucial to understand its core concepts:


VPCs create a logical boundary that separates your resources from others in the AWS cloud. This isolation enhances security and prevents accidental interactions between different workloads.

Subnet Masks

VPCs use subnet masks to divide the available IP address space into smaller, manageable units. This organization allows you to group resources based on their function, security needs, and network requirements.

CIDR Notation

Classless Inter-Domain Routing (CIDR) notation defines network ranges and subnet allocations in AWS VPC. This notation provides an efficient way to represent IP address blocks.

Internet Gateway

An Internet Gateway enables your VPC to connect to the public internet, allowing your resources to communicate with external services.

NAT Gateway

A Network Address Translation (NAT) gateway allows instances in private subnets to access the internet without exposing their private IP addresses. This adds an extra layer of security by keeping internal resources shielded from direct external connections.

Security Groups

Security groups act as virtual firewalls, controlling inbound and outbound traffic at the instance level. Rules within security groups specify which connections are allowed or denied based on criteria like source IP, port, and protocol.

Creating and Configuring Your AWS VPC

Step 1: Region Selection

Choose the AWS region where you want your VPC to reside. Selecting the right region is crucial for latency and compliance reasons.

Step 2: Define a CIDR Block

Define the initial IP address range for your VPC using CIDR notation. For example,

Step 3: Subnet Creation

Divide your VPC into subnets, assigning each subnet a specific CIDR block. Consider separating subnets based on application requirements, security needs, or availability zones.

  1. Public Subnets: For resources that need direct access to the internet.
  2. Private Subnets: For internal resources that should not be directly accessible from the internet.

Step 4: Internet Gateway

If you require internet connectivity for your VPC, create an Internet Gateway and attach it to your VPC.

# Example AWS CLI command to create an Internet Gateway
aws ec2 create-internet-gateway
aws ec2 attach-internet-gateway --vpc-id vpc-xxxxxxx --internet-gateway-id igw-xxxxxxx

Step 5: NAT Gateway

If instances in private subnets need to access the internet, create a NAT gateway within a public subnet.

# Example AWS CLI command to create a NAT Gateway
aws ec2 create-nat-gateway --subnet-id subnet-xxxxxxx --allocation-id eipalloc-xxxxxxx

Step 6: Security Groups

Create security groups to control the traffic flow for your instances. Define inbound and outbound rules based on your application’s requirements.

# Example AWS CLI command to create a Security Group
aws ec2 create-security-group --group-name my-sg --description "My security group" --vpc-id vpc-xxxxxxx

Advanced VPC Concepts

Network Access Control Lists (ACLs)

ACLs provide an additional layer of security, controlling traffic at the subnet level. They are more granular than security groups and can filter traffic based on source and destination IP addresses, ports, and protocols.

VPN Connections

Establish secure connections between your VPC and on-premises network using AWS VPN. This allows you to extend your existing infrastructure into the cloud seamlessly.

VPC Peering

VPC Peering connects two VPCs in the same or different AWS accounts, allowing resources in different VPCs to communicate without exposing them to the public internet.

Flow Logs

Enable Flow Logs to monitor network traffic within your VPC. Flow Logs provide valuable insights into network activity, helping you identify potential security threats or performance bottlenecks.

# Example AWS CLI command to create a VPC Flow Log
aws ec2 create-flow-logs --resource-id vpc-xxxxxxx --resource-type VPC --traffic-type ALL --log-group-name my-flow-logs --deliver-logs-permission-arn arn:aws:iam::123456789012:role/flow-logs-role

Best Practices for AWS VPC


Divide your VPC into logical subnets based on function and security requirements. For example, separating web servers, application servers, and databases into different subnets.

Security Groups and ACLs

Implement appropriate security rules to protect your resources from unauthorized access. Regularly review and update these rules to adapt to changing security requirements.

Private Subnets

Place sensitive applications or databases within private subnets to limit their exposure to the public internet.

NAT Gateway

Use NAT gateways to enable internet access for instances within private subnets without exposing their private IP addresses.

Flow Logs

Enable Flow Logs to gain valuable insights into network traffic within your VPC. Regularly review these logs to identify and mitigate potential issues.


Utilize AWS CloudWatch to monitor your VPC resources and receive alerts for any anomalies or unusual activity. This helps in maintaining the health and security of your VPC.

Cost Considerations

  • Free Tier: AWS offers a free tier with limited usage for VPC-related resources, including some data transfer and a small number of VPCs, subnets, and security groups.
  • Chargeable Services:
  • NAT Gateway: Charged based on data processed and hourly usage.
  • VPN Connection: Charged hourly for each VPN connection.
  • Flow Logs: Charged based on the amount of log data captured.
  • Internet Gateway: Typically, there is no cost for the gateway itself, but data transfer costs apply.


AWS VPC is a critical component for creating a secure, flexible, and scalable cloud infrastructure. By understanding the concepts and best practices outlined in this guide, you can effectively leverage VPC to build robust, reliable, and secure solutions. Whether you’re setting up a simple network or a complex architecture, mastering VPC configuration will enable you to optimize performance, enhance security, and ensure seamless connectivity.

By following this practical guide, you’ll be well-equipped to configure and manage your own custom VPC, taking full advantage of AWS’s powerful networking capabilities.



Bhavyansh @ DiversePixel

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