Networking Fundamentals

Learning Path

📘 Phase 1 – Overview

🎯 Lesson Objective

By the end of this lesson, you will be able to:

Understand networking fundamentals used in cloud environments.
Explain how devices communicate over a network.
Understand IP addressing, DNS, routing and ports.
Learn how AWS networking builds upon traditional networking concepts.
Identify common network security controls.
Troubleshoot basic network connectivity issues.

📚 Lesson Information

Estimated Time: 2 Hours

Difficulty: Beginner

Prerequisites: Identity & Access Fundamentals

Hands-on Lab: Yes

Assignment: Yes

💼 Business Value

Every cloud application depends on networking.

If users cannot reach an application, the business stops.

Cloud Security Engineers must understand how traffic flows between users, applications, databases, and cloud services so they can design secure, resilient, and highly available environments.

Networking is one of the most important skills for every cloud professional.

🌍 What is Networking?

Networking is the process of connecting devices so they can communicate and exchange information.

Examples include:

Laptop ↔ Internet
Mobile App ↔ API
EC2 ↔ Database
Browser ↔ Website
Cloud ↔ On-Premises Network

Without networking, cloud computing would not exist.

🏢 Enterprise Networking

Imagine CloudNova Technologies hosts an online shopping application.

When a customer opens:

https://shop.cloudnova.com

The request follows this journey:

Customer Device
        │
        ▼
Internet
        │
        ▼
DNS
        │
        ▼
Load Balancer
        │
        ▼
Web Server
        │
        ▼
Application Server
        │
        ▼
Database
        │
        ▼
Storage

Every component communicates over a network.

A Cloud Security Engineer protects every stage of this communication.

🌐 IP Addresses

Every device connected to a network requires an IP address.

Think of an IP address as the postal address of a computer.

Example IPv4 address:

192.168.1.10

Example IPv6 address:

2406:da18:4d0:abcd::100

Without an IP address, devices cannot communicate.

🏠 Public vs Private IP Addresses

Public IP

Accessible from the internet.

Examples:

Public websites
APIs
Internet-facing applications

Example:

54.239.28.85

Private IP

Used inside private networks.

Not directly accessible from the internet.

Examples:

10.0.0.15
172.16.5.20
192.168.1.100

AWS VPCs primarily use private IP addresses.

🌍 DNS (Domain Name System)

Humans remember names.

Computers use IP addresses.

DNS translates:

www.amazon.com

into

54.x.x.x

Without DNS, users would need to remember IP addresses.

🌐 Routing

Routers determine where network traffic should travel.

Example:

Laptop
   │
   ▼
Home Router
   │
   ▼
Internet
   │
   ▼
AWS Region
   │
   ▼
Application

Routing ensures data reaches the correct destination.

🚪 Ports

A single server can run multiple services simultaneously.

Ports identify those services.

Common ports include:

Port	Protocol	Service
20/21	TCP	FTP
22	TCP	SSH
25	TCP	SMTP
53	TCP/UDP	DNS
80	TCP	HTTP
110	TCP	POP3
143	TCP	IMAP
443	TCP	HTTPS
3306	TCP	MySQL
3389	TCP	RDP
5432	TCP	PostgreSQL

Only required ports should be accessible.

📡 Network Protocols

Protocols define how devices communicate.

Common protocols include:

Protocol	Purpose
HTTP	Web Traffic
HTTPS	Secure Web Traffic
DNS	Name Resolution
SSH	Secure Remote Administration
FTP	File Transfer
SMTP	Email Sending
IMAP	Email Retrieval
TCP	Reliable Communication
UDP	Fast Communication

🔄 TCP vs UDP

TCP

Reliable communication.

Characteristics:

Ordered delivery
Error checking
Acknowledgements
Slower
Reliable

Used for:

HTTPS
SSH
Email
Banking Applications

UDP

Fast communication.

Characteristics:

No acknowledgements
Lower overhead
Faster
Less reliable

Used for:

Video Streaming
Voice Calls
Online Gaming
DNS Queries

🛡️ Firewalls

A firewall controls network traffic.

It decides:

Who can connect
Which ports are allowed
Which traffic is blocked

Example:

Internet
      │
      ▼
Firewall
      │
      ▼
Web Server

AWS uses:

Security Groups
Network ACLs
AWS Network Firewall

🔐 VPN (Virtual Private Network)

A VPN creates an encrypted connection over the internet.

Benefits:

Secure remote access
Protects data in transit
Connects on-premises networks to AWS
Enables hybrid cloud connectivity

🌍 Load Balancer

A Load Balancer distributes incoming traffic across multiple servers.

Benefits:

High Availability
Scalability
Fault Tolerance
Better Performance

Example:

Users
   │
   ▼
Load Balancer
 ┌──┴──┐
 ▼     ▼
Web1  Web2
  \   /
   \ /
   Web3

☁️ Networking in AWS

AWS networking is built around the Virtual Private Cloud (VPC).

Key components include:

VPC
Subnets
Route Tables
Internet Gateway
NAT Gateway
Security Groups
Network ACLs
Elastic IP Addresses
VPC Endpoints
Transit Gateway

You will learn these services in detail later in the course.

🔐 Networking Best Practices

Cloud Security Engineers should:

Use private subnets whenever possible.
Allow only required ports.
Block unnecessary inbound traffic.
Encrypt traffic using HTTPS.
Use VPNs for remote access.
Monitor network traffic.
Segment environments using subnets.
Apply the principle of Least Privilege to network access.

🏢 Enterprise Scenario

CloudNova Technologies

CloudNova Technologies hosts a three-tier application.

Current issues:

Database is publicly accessible.
SSH (Port 22) is open to the entire internet.
HTTP (Port 80) is used instead of HTTPS.
No Load Balancer exists.
No VPN is configured for administrators.

As the Cloud Security Engineer:

Identify the networking risks.
Recommend improvements.
Which AWS networking services would you implement?
Which issues should be resolved first?

🧪 Hands-on Exercise 1 — Identify Your IP Address

Windows

ipconfig

Linux

ip addr

ifconfig

macOS

ifconfig

Identify:

IPv4 Address
Default Gateway
DNS Server

Questions:

Is your IP public or private?
Why?

🧪 Hands-on Exercise 2 — Test Connectivity

ping google.com

Observe:

Response time
Packet loss
Connectivity

Questions:

Why is latency important?
What happens if packets are lost?

🧪 Hands-on Exercise 3 — Trace Network Path

Windows

tracert google.com

Linux/macOS

traceroute google.com

Observe:

Number of hops
Intermediate routers

Questions:

Why does traffic travel through multiple routers?
How could attackers use traceroute information?

🧪 Hands-on Exercise 4 — DNS Lookup

Windows

Resolve-DnsName amazon.com

Linux/macOS

dig amazon.com

nslookup amazon.com

Observe:

IP addresses
Name Servers
TTL values

Questions:

Why are multiple IP addresses returned?
How does DNS improve availability?

🧪 Hands-on Exercise 5 — Port Scanning

Install Nmap.

Ubuntu/Debian

sudo apt update
sudo apt install nmap

Fedora

sudo dnf install nmap

macOS

brew install nmap

Windows

Download and install Nmap from the official website.

Run:

nmap localhost

Questions:

Which ports are open?
Which services are listening?
Which ports could be disabled?

Important: Only scan systems that you own or have explicit permission to test.

🧪 Hands-on Exercise 6 — HTTP Header Inspection

Run:

curl -I https://aws.amazon.com

Identify:

HTTP Status
Server
Content-Type
Strict-Transport-Security
Content-Security-Policy

Questions:

Why are security headers important?
How do they improve application security?

📊 Knowledge Check

Answer the following questions:

What is an IP address?
What is the difference between public and private IP addresses?
What is DNS?
What is routing?
What is a network port?
What is the difference between TCP and UDP?
Why are firewalls important?
What is a VPN?
Why do organisations use Load Balancers?
Name five AWS networking services.

📝 Assignment

Prepare a Network Security Assessment Report for CloudNova Technologies.

Include:

Explain how users access the cloud application.
Identify all networking components.
Recommend secure network architecture.
Identify networking risks.
Recommend AWS networking services.
Suggest security improvements.

Length: 2–3 pages.

💡 Key Takeaways

After completing this lesson, you should understand:

How devices communicate over networks.
The purpose of IP addresses, DNS, routing, and ports.
The difference between TCP and UDP.
Why firewalls, VPNs, and Load Balancers are essential.
How networking forms the foundation of cloud infrastructure.
How Cloud Security Engineers protect network communication.

📚 Further Reading

AWS VPC Documentation
AWS Networking & Content Delivery Services
RFC 791 (IPv4)
RFC 8200 (IPv6)
NIST SP 800-41 - Guidelines on Firewalls and Firewall Policy

🚀 Next Lesson

➡️ Encryption Fundamentals