Unit 9.8
Network Security: Firewalls and Encryption
Learning Objectives 🎯
By the end of this chapter, you will be able to:
- ✅ Define network security and its goals.
- ✅ Describe the function of a firewall as a network barrier.
- ✅ Define encryption and decryption and their role in data confidentiality.
What is Network Security?
Network Security: The policies and practices adopted to protect a computer network and its resources.
The primary goals are to:
- 🛡️ Prevent unauthorized access.
- 🔍 Monitor for misuse or modification.
- 🚫 Deny attacks and disruptions.
Our First Line of Defense: The Firewall
Think of a firewall as a digital gatekeeper for your network.
Trusted Network
(Your Home or Office)
Untrusted Network
(The Internet)
A firewall stands between these two, inspecting all traffic.
How a Firewall Works
The Definition 📖
A network security device that monitors incoming and outgoing traffic, allowing or blocking it based on a set of security rules.
The Analogy 🤔
It's like a security guard at a building entrance.
- Checks everyone's ID (IP Address).
- Has a list of allowed visitors (Rules).
- Denies entry to anyone suspicious (Blocks Traffic).
Where are Firewalls Located?
They can be software on your computer or dedicated hardware.
🏠 Home Network
Often built directly into your Wi-Fi router (e.g., from WorldLink, Vianet).
🏢 University/Corporate
Powerful, dedicated hardware devices protecting the entire campus network.
💻 Personal Computer
Software firewalls like Windows Defender or macOS Firewall protect your individual device.
Protecting the Data Itself ⚡
A firewall protects the network, but what about the information traveling across it?
This is where Encryption comes in.
Encryption and Decryption
Encryption 🔒
The process of converting readable data (plain text) into an unreadable, coded format (ciphertext).
Hello World ➡️ aJk8$Lp#wQ!z
Decryption 🔓
The process of converting ciphertext back into plain text. This requires a secret key.
aJk8$Lp#wQ!z ➡️ Hello World
The Role of the Key 🔑
Encryption uses an algorithm and a key.
Analogy: The algorithm is the type of lock (e.g., a padlock). The key is the unique physical key that can open that specific lock.
- Without the correct key, the ciphertext is just random, meaningless data.
- This is the most effective way to ensure data confidentiality.
Practical Application in Nepal 🇳🇵
Why is encryption vital for online services?
When you use services like eSewa, Khalti, or Daraz, encryption protects your:
- 💳 Payment details (bank account, card numbers).
- 👤 Personal information (name, address, phone number).
- 🔑 Login credentials (username and password).
It ensures that even if a hacker intercepts the data, they cannot read or use it.
Summary & Key Takeaways
- 🛡️ Network security is a set of practices to protect a network from unauthorized access and misuse.
- 🧱 A firewall acts as a barrier or gatekeeper, filtering network traffic based on predefined security rules.
- 🔒 Encryption scrambles data into an unreadable format to protect its confidentiality, while decryption unscrambles it with a key.
Thank You!
Any questions?
Next Up: Chapter 9 - Common Cybersecurity Threats