Computer Networking Essentials for DevOps: Learn How the Internet Works

In the world of DevOps, understanding computer networking is crucial. Whether you're deploying applications, managing cloud infrastructure, or troubleshooting connectivity issues, networking fundamentals play a key role. In this blog, we'll explore:

1. How the Internet Works

2. The OSI Model

3. The TCP/IP Model

4. Important Networking Protocols

5. Hands-on Demo with AWS (VPC, Subnets, CIDR, Gateways, Route Tables)

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1. How Does the Internet Work?

The internet is a global network of interconnected computers and servers that communicate using standardized protocols. Here's a simplified breakdown:

• Devices (Clients & Servers): Your laptop (client) requests data from a server (e.g., a website hosted on AWS).

• IP Addresses: Every device has a unique IP (e.g., 192.168.1.1 or 2001:0db8:85a3::8a2e:0370:7334 for IPv6).

• DNS (Domain Name System): Converts human-readable names (e.g., google.com) to IP addresses.

• Routers & Switches: Direct traffic efficiently across networks.

• Packets: Data is broken into small chunks (packets) and reassembled at the destination.

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2. The OSI Model (7 Layers)

The Open Systems Interconnection (OSI) model standardizes network communication into seven layers:

Why it matters for DevOps?

• Helps troubleshoot network issues (e.g., is the problem at Layer 3 (IP) or Layer 4 (TCP)?

• Security policies (e.g., firewalls at Layer 4 vs. Layer 7).

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3. The TCP/IP Model (Simplified OSI)

The TCP/IP model is the practical implementation used on the internet:

Key Differences:

• TCP/IP combines OSI’s top 3 layers into Application.

• More aligned with real-world internetworking.

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4. Important Networking Protocols

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5. AWS Networking Demo (VPC, Subnets, Gateways, Route Tables)

Let’s deploy a simple AWS network to see these concepts in action.

Step 1: Create a VPC (Virtual Private Cloud)

• A VPC is your private network in AWS.

• Go to AWS VPC Console → Create VPC.

• Set IPv4 CIDR block (e.g., 10.0.0.0/16 → 65,536 IPs).

Step 2: Create Subnets

• Subnets divide your VPC into smaller networks.

• Example:

  • Public Subnet (10.0.1.0/24) – For web servers.

  • Private Subnet (10.0.2.0/24) – For databases.

Step 3: Set Up an Internet Gateway (IGW)

• Allows public subnet to access the internet.

• Attach IGW to your VPC.

Step 4: Configure Route Tables

• A route table defines traffic rules.

• For public subnet, add:

    Destination: 0.0.0.0/0 (Internet)  
    Target: igw-xxxx (Internet Gateway)
  

Step 5: Launch an EC2 Instance

• Deploy an EC2 instance in the public subnet.

• Assign a public IP.

• Test internet access (ping google.com).

Step 6: Security Groups & NACLs

• Security Group (Firewall for instances): Allow SSH (port 22), HTTP (80).

• NACL (Subnet-level firewall): Stateless rules for inbound/outbound.

Expected Result:

• EC2 in public subnet can reach the internet.

• Private subnet remains isolated (unless using NAT Gateway).

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Conclusion

Understanding networking is essential for DevOps engineers. From the OSI model to AWS VPCs, these concepts help in:

• Deploying scalable apps (e.g., microservices in subnets).

• Troubleshooting connectivity (e.g., checking route tables).

• Securing cloud environments (e.g., NACLs, Security Groups).

Try replicating the AWS demo yourself! 🚀

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Further Learning:

• AWS VPC Documentation

• TCP/IP Illustrated (Book)

Let me know in the comments if you'd like a deeper dive into any topic! 🚀