Firewall for Beginners – Simple Introduction

[NetGuru]

What Is a Firewall?

A firewall is a security system that monitors and controls incoming and outgoing network traffic based on defined rules.

It acts as a barrier between a trusted network (like your home or server) and untrusted networks (like the internet).

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1. Why Do You Need a Firewall?

Without a firewall, your system would be directly exposed to the internet.

A firewall helps to:

• Block unauthorized access
• Protect services and ports
• Prevent attacks
• Control network traffic

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2. How a Firewall Works

A firewall checks network traffic and decides:

• Allow the connection
• Block the connection

Example:

• Allow port 80 (web server)
• Allow port 443 (HTTPS)
• Block all other incoming traffic

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3. Types of Firewalls

1. Network Firewall

• Protects an entire network
• Usually built into routers

2. Host-Based Firewall

• Runs on a single system
• Controls traffic for that device

Examples:

• UFW (Uncomplicated Firewall)
• iptables / nftables

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4. Common Firewall Rules

• All

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