DevOps Week 1: Networking Fundamentals

Welcome to Week 1 of the 90DaysOfDevOps – 2025 Edition! Whether you’re from an IT background or not, this blog is for you*. Let’s understand networking in the simplest way possible.* 🌐

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🔹 What is Networking in DevOps?

In simple terms, networking means connecting computers or devices together so they can talk to each other. In DevOps, networking is important because we work with cloud servers, deploy apps, and ensure everything communicates safely and smoothly.

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📘 1. OSI & TCP/IP Models — The Basics

Think of sending a message to your friend. You type, press send, the message travels, reaches your friend, and they reply. Similarly, computer communication happens through layers.

🧩 OSI Model (7 Layers):

📦 TCP/IP Model (4 Layers):

It’s a simplified real-world model:

• Application (e.g., HTTP)

• Transport (e.g., TCP/UDP)

• Internet (e.g., IP)

• Network Access (Wi-Fi, Ethernet)

👉 Real Example:
When you visit www.google.com:

• Your browser (Application Layer) sends a request.

• TCP breaks the request into packets (Transport).

• IP finds the best path to Google (Internet).

• Data is transferred over Wi-Fi (Network Access).

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🌐 2. Protocols & Ports Every DevOps Engineer Must Know

Protocols & Ports

🛠 Task: Learn which service runs on which port.
Example: If a server isn’t responding on port 22, SSH access may be blocked!

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☁️ 3. AWS EC2 + Security Groups

Amazon EC2 = Virtual Computer in the Cloud.

🔐 What Are Security Groups?

They act like firewalls – allowing/blocking incoming/outgoing traffic.

✅ You allow port 22 to connect via SSH.
✅ You allow port 80/443 for web access.

This image explains how only allowed network traffic (via open ports like 22 or 80/443) can reach your server, while malicious traffic is blocked by a firewall or port configuration.

📋 Step-by-Step:

1. Go to AWS EC2 Dashboard.

2. Launch a free-tier Ubuntu instance.

3. In Security Groups:

   • Allow port 22 (SSH)

   • Allow port 80 (HTTP)

   • Allow port 443 (HTTPS)

4. Connect to instance using:

ssh -i "your-key.pem" ubuntu@your-public-ip

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💻 4. Common Networking Commands Cheat Sheet

👉 These commands help you debug network issues and ensure your apps can connect properly.

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📝 Summary of Week 1

✅ Understood OSI & TCP/IP with real-world examples
✅ Learned key networking protocols & ports
✅ Launched AWS EC2 instance with correct Security Groups
✅ Practiced essential networking commands

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📢 Final Thoughts

Networking is the base of everything in DevOps. From cloud servers to CI/CD pipelines, good networking knowledge saves time and prevents errors.

💡 If you can ping it, you can reach it! If you can't — troubleshoot the layers! 😄

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GitHub Repo: 90DaysOfDevOps
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