As networks grow and become more connected to the internet, protecting them from threats becomes essential. In IB Computer Science, this protection is explained using firewalls. Students are expected to understand what a firewall is, what it does, and the difference between hardware and software firewalls.
Firewalls are a key part of network security questions and are often assessed in scenario-based explanations.
What Is a Firewall?
A firewall is a security system that:
- Monitors network traffic
- Controls what data is allowed to enter or leave a network
- Blocks unauthorised or suspicious activity
Firewalls work by applying a set of rules to network traffic. These rules decide whether data packets are:
- Allowed through
- Blocked
- Logged for monitoring
In IB Computer Science, firewalls are described as a barrier between trusted and untrusted networks.
Why Firewalls Are Needed
Firewalls are used to:
- Prevent unauthorised access
- Protect sensitive data
- Reduce the risk of attacks
- Control network traffic
Without a firewall, a network connected to the internet would be exposed to:
- Malware
- Hacking attempts
- Data theft
Firewalls are one of the first lines of defence in network security.
What Is a Hardware Firewall?
A hardware firewall is a physical device placed between a network and external connections.
Key characteristics:
- Usually part of a router or dedicated security appliance
- Protects all devices on the network
- Operates independently of individual computers
Hardware firewalls:
- Filter traffic before it reaches devices
- Are always active
- Are harder for attackers to disable
In IB exam answers, hardware firewalls are often linked to:
- Business networks
- Schools
- Enterprise systems
What Is a Software Firewall?
A software firewall is a program installed on an individual device.
Key characteristics:
- Runs on a computer or server
- Protects only that device
- Can be customised per application
Software firewalls:
- Monitor incoming and outgoing traffic
- Allow users to set application-specific rules
- Provide detailed alerts and logs
They are commonly used on:
- Personal computers
- Laptops
- Servers
Comparing Hardware and Software Firewalls
Strong IB answers compare both clearly:
- Hardware firewall
- Network-wide protection
- More difficult to bypass
- Less granular control per device
- Software firewall
- Device-level protection
- Highly configurable
- Can be disabled by malware if compromised
Many networks use both for layered security.
Firewalls and Network Segmentation
Firewalls are often used together with:
- Network segmentation
- Access control rules
This allows organisations to:
- Restrict traffic between segments
- Protect sensitive areas
- Monitor specific data flows
IB questions may link firewalls directly to segmentation and security strategy.
Common Student Mistakes
Students often:
- Say firewalls block all traffic
- Confuse firewalls with antivirus software
- Ignore outgoing traffic control
- Forget the difference between hardware and software firewalls
Clear definitions and comparisons earn marks.
How Firewalls Appear in IB Exams
Students may be asked to:
- Explain what a firewall does
- Compare hardware and software firewalls
- Justify firewall use in a scenario
- Link firewalls to security and access control
Justification is more important than memorisation.
Final Thoughts
Firewalls control network traffic by enforcing security rules. Hardware firewalls protect entire networks, while software firewalls protect individual devices. Together, they form a critical part of modern network security.
Understanding how and why firewalls are used allows IB Computer Science students to explain real-world security decisions clearly and confidently — exactly what examiners expect.
