Protecting networks (Edexcel GCSE Computer Science): Revision Notes
Protecting networks
Network security is crucial for any organisation that wants to keep their data safe from hackers and unauthorised users. There are several layers of protection that work together to create a secure network environment.
Access control
Access control is like having a bouncer at a club - it decides who gets in and what they're allowed to do once they're inside. This system limits who can log into a network and controls what permissions they have.
Access control forms the first line of defence in network security. Without proper access controls, even the most sophisticated security measures can be bypassed by unauthorised users who gain legitimate-looking credentials.
Authentication methods
Authentication is the process of proving you are who you say you are when trying to access a network. Think of it like showing your ID card to prove your identity.
Single authentication typically involves:
- Username and password combinations
- This is the most basic form but also the most vulnerable
Single-factor authentication using only passwords is the weakest form of security. Studies show that over 80% of data breaches involve compromised passwords, making this approach highly vulnerable to modern cyber attacks.
Multi-factor authentication provides much stronger security by requiring multiple forms of proof:
- Something you know (like a password)
- Something you have (like a phone or swipe card)
- Something you are (like your fingerprint or face)
Worked Example: Multi-Factor Authentication in Practice
When logging into your online banking:
- Something you know: Enter your username and password
- Something you have: Receive a text message with a 6-digit code on your registered phone
- Something you are: Some banks also use fingerprint scanning on mobile apps
This layered approach means that even if someone steals your password, they still can't access your account without your phone and biometric data.
Biometric authentication uses your unique physical characteristics such as:
- Fingerprints
- Facial recognition
- Eye scans (iris or retina)
- Voice patterns
The key advantage of biometric data is that it's always with you and cannot be easily stolen, lost, or forgotten like a password or card.
Permission levels
Once someone is authenticated, the system needs to control what they can access. This works through different permission levels:
- Read-only access: Users can view files but cannot make any changes
- Read and write access: Users can view and modify files
- Administrative access: Users can delete files and change other users' permissions
Think of this like different levels of access in a school - students might only be able to read certain files, teachers can modify them, and IT administrators have full control.
Properly configured permission levels are essential for maintaining data integrity and preventing accidental or malicious damage to important files and systems.
Physical security
Physical security focuses on preventing unauthorised people from physically reaching network equipment. After all, if someone can physically access your servers, they could potentially bypass all your digital security measures.
Building access controls
Secure doors and entry points:
- Access doors should remain locked at all times
- Security keypads require users to enter a code
- Card readers scan employee ID badges
- Biometric scanners can verify fingerprints or other physical features
Monitoring systems:
- CCTV (Closed-circuit television) cameras monitor building exteriors and interiors
- Security personnel can watch for suspicious activity
- Recordings provide evidence if security breaches occur
Equipment tracking:
- RFID (Radio Frequency Identification) chips can be attached to valuable equipment
- These chips trigger alarms if equipment is moved without authorisation
- They help track the location of important devices
Physical security is often overlooked but is just as important as digital security. A single unauthorised person with physical access to servers can potentially compromise an entire network, regardless of how sophisticated the digital security measures are.
Principle of least privilege
This is a fundamental security concept that means giving users only the minimum level of access they need to do their job effectively. Network managers apply this principle when setting up user accounts and file permissions.
Worked Example: Applying Least Privilege in a Company
In a typical office environment:
-
A receptionist might only need access to:
- Appointment scheduling software
- Basic email system
- Phone directory
-
An accountant would need access to:
- Financial systems and databases
- Payroll software
- But NOT HR personal records or IT systems
-
A manager might need broader access to:
- Multiple departmental systems
- Reports and analytics tools
- But still not full administrative privileges
This approach limits damage if an account gets compromised - hackers can only access what that particular user was allowed to see.
Firewalls
A firewall acts like a security checkpoint between your internal network and the outside world (usually the internet). It examines all data trying to enter or leave the network and decides whether to allow it through.
How firewalls work
Firewalls can be configured with rules that determine what traffic to block or allow. They can:
- Block incoming connections from suspicious IP addresses
- Prevent certain programs from accessing the internet
- Filter web content to block dangerous websites
- Monitor outgoing traffic to detect if malware is trying to communicate with external servers
Modern firewalls use sophisticated rule sets that can analyse not just where traffic is coming from, but also what type of data is being transmitted and whether it matches expected patterns for legitimate network activity.
Types of firewalls
Software firewalls:
- Installed on individual computers
- Come with default security rules
- Suitable for home users and small offices
- Less expensive but limited in features
Hardware firewalls:
- Dedicated physical devices (like PC-sized appliances)
- Protect entire networks rather than individual computers
- More flexible and configurable
- Allow faster data processing
- Better suited for businesses with complex security needs
The firewall sits between your Local Area Network (LAN) and the Wide Area Network (WAN), inspecting all traffic that passes between them.
Real-world applications
These security measures are used everywhere in modern digital infrastructure:
- Banks use multi-factor authentication for online banking to protect customer accounts
- Hospitals apply least privilege to protect sensitive patient records and comply with privacy laws
- Schools use firewalls to philtre inappropriate content and protect students online
- Offices combine physical security with access controls to create comprehensive protection
The combination of these security measures creates what security professionals call "defence in depth" - multiple layers of protection that work together to provide comprehensive security coverage.
Exam tips
Key Points for Exam Success:
- Remember the different types of authentication: single factor vs multi-factor, and why MFA is more secure
- Understand why biometric authentication is considered secure: it's unique to each person and always with you
- Know the difference between hardware and software firewalls: hardware protects entire networks, software protects individual devices
- Be able to explain the principle of least privilege with practical examples from different job roles
- Practice describing how each security measure works in your own words using real-world analogies
Key takeaways
Essential Concepts to Remember:
- Access control manages who can log in and what they can do through authentication and permissions
- Physical security prevents unauthorised people from physically accessing network equipment
- Multi-factor authentication is much more secure than passwords alone because it requires multiple forms of verification
- Firewalls act as security checkpoints between internal networks and external connections like the internet
- Principle of least privilege means giving users only the minimum access they need for their job role