Networking III - SSS 3 Note
NETWORKING III
Class: SSS 3
Term: Second Term
Week: 3
Topic: Networking III
Duration: 80 Minutes (Double Period)
Learning Objectives
By the end of the lesson, students should be able to:
- Explain the meaning and importance of network security.
- Identify common network security threats.
- Explain the meaning and purpose of a Virtual Private Network (VPN).
- Describe basic methods of securing network communications.
- Apply appropriate safety practices when using networks and the internet.
1. Introduction to Network Security
Computer networks allow computers and other digital devices to exchange information and share resources. Networks are used in schools, offices, banks, hospitals and homes. However, network connections may expose users and their information to security risks if they are not properly protected.
1.1 Importance of Network Security
Network security is important for the following reasons:
- Protection of information: It helps prevent unauthorised people from accessing private files and sensitive data.
- Prevention of unauthorised access: It ensures that only approved users and devices can access protected network resources.
- Protection against malware: It helps reduce the risk of viruses, ransomware and other malicious software spreading through a network.
- Privacy: It helps protect personal, school and business information.
- Availability of services: It helps keep network resources and online services accessible to authorised users.
- Reliable communication: It helps protect information exchanged through email, messaging applications and other network services.
1.2 Main Goals of Network Security
Three important goals of information and network security are confidentiality, integrity and availability.
| Goal | Meaning | Example |
|---|---|---|
| Confidentiality | Information is accessible only to authorised people. | Using access permissions to protect students' records. |
| Integrity | Information remains accurate and is not changed without permission. | Preventing an unauthorised person from altering examination scores. |
| Availability | Systems and information remain accessible when authorised users need them. | Protecting a school portal against attacks that could make it unavailable. |
2. Common Network Security Threats
A network security threat is a possible danger that may exploit a weakness in a network or its devices to steal information, damage systems or interrupt services.
2.1 Malware
Malware means malicious software designed to damage devices, disrupt operations, steal information or gain unauthorised access.
Common types include:
- Virus: Malicious code that attaches itself to files or programs and can spread when they are used.
- Worm: Malware that can copy and spread itself between devices or networks.
- Trojan horse: Malicious software disguised as a legitimate or useful program.
- Ransomware: Malware that locks or encrypts data and demands payment to restore access.
- Spyware: Software designed to monitor activity or collect information without proper permission.
2.2 Phishing
Phishing is an attempt to trick people into revealing confidential information or performing unsafe actions through deceptive emails, messages, websites or links.
For example, a student may receive a fake message claiming that a school account will be closed unless the student enters a password on an unfamiliar website.
2.3 Unauthorised Access
Unauthorised access occurs when someone enters a computer, network or account without permission. This may happen through stolen passwords, poorly protected devices or weaknesses in security settings.
2.4 Password Attacks
Attackers may attempt to guess, steal or repeatedly test passwords to gain access to accounts and network resources. Reusing simple passwords across multiple accounts increases the risk.
2.5 Eavesdropping and Data Interception
Eavesdropping occurs when someone secretly monitors communications. If network traffic is not adequately protected, an attacker may attempt to observe or capture information being transmitted.
2.6 Denial-of-Service (DoS) Attacks
A denial-of-service attack attempts to make a network service unavailable by overwhelming it with requests or otherwise disrupting its operation. A distributed denial-of-service (DDoS) attack uses many devices or sources to carry out the attack.
2.7 Spoofing
Spoofing occurs when an attacker disguises a device, identity, address or communication as something trusted. It may be used to mislead users or systems.
2.8 Unsecured Wi-Fi Networks
Public or poorly secured Wi-Fi networks may expose users to fake hotspots, unauthorised monitoring or other attacks. Users should be careful when accessing sensitive accounts through unfamiliar networks.
Summary of Common Threats
| Threat | Possible Effect | Basic Protection |
|---|---|---|
| Malware | Damaged files, stolen information or disrupted systems. | Use updated security software and obtain downloads from trusted sources. |
| Phishing | Stolen passwords or personal information. | Verify messages and avoid suspicious links. |
| Password attacks | Unauthorised access to accounts. | Use strong, unique passwords and multifactor authentication. |
| Eavesdropping | Exposure of transmitted information. | Use secure connections and trusted networks. |
| DoS/DDoS | Network services become slow or unavailable. | Use appropriate network protection and monitoring. |
| Unsecured Wi-Fi | Greater risk of interception or fake hotspots. | Use trusted networks and secure connections. |
3. Virtual Private Networks (VPNs)
A VPN can help protect data in transit between a user's device and the VPN endpoint. It is commonly used by employees to connect securely to an organisation's network from outside the office and by individuals who want additional protection on certain network connections.
3.1 How a VPN Works
- The user connects to a VPN service or an organisation's VPN server.
- The VPN establishes a protected connection using suitable security protocols.
- Data travelling through the VPN tunnel is encrypted according to the VPN configuration.
- The VPN endpoint processes the traffic and forwards it to the intended destination where appropriate.
3.2 Uses of VPNs
- Remote work: Employees can securely access authorised company resources from another location.
- Remote learning: An institution may use a VPN to provide authorised access to internal learning resources.
- Protection on public Wi-Fi: A properly configured VPN can reduce the risk of local network observers reading the protected traffic travelling through its tunnel.
- Private network access: Organisations can allow approved users to reach internal systems without exposing every resource directly to the public internet.
3.3 Advantages of VPNs
- Encrypts traffic between the device and the VPN endpoint when properly configured.
- Can support secure remote access to private organisational networks.
- Can reduce the exposure of certain network activities to other users on the same local network.
- Can help organisations apply access controls to remote connections.
3.4 Limitations of VPNs
- A VPN does not guarantee complete anonymity online.
- It does not automatically protect a device from viruses, phishing or every form of cyberattack.
- The VPN provider or organisation operating the endpoint may be able to observe some connection information.
- A VPN does not make an unsafe website trustworthy.
- Free or unreliable VPN services may have weak security, intrusive advertising or questionable privacy practices.
4. Basic Methods of Securing Network Communications
Network communications can be protected through a combination of technical controls and responsible user behaviour.
4.1 Use Strong and Unique Passwords
Passwords should be difficult to guess. Users should avoid obvious choices such as their names, birthdays or simple number sequences. Each important account should have a unique password.
4.2 Enable Multifactor Authentication (MFA)
Multifactor authentication requires an additional form of verification beyond a password, such as an authentication-app code or a security key. This provides extra protection if a password is stolen.
4.3 Use Encryption
Encryption converts readable information into a protected form that cannot easily be understood without the required key. Secure websites commonly use HTTPS to protect information exchanged between a browser and a website.
4.4 Install and Update Security Software
Antivirus or endpoint security software can help detect and block malicious programs. Security software and operating systems should be updated regularly to address known weaknesses.
4.5 Use Firewalls
A firewall monitors and controls network traffic according to defined security rules. It can help block unwanted connections while allowing approved traffic.
4.6 Secure Wi-Fi Networks
- Change the default administrator password on a router.
- Use modern Wi-Fi security settings, such as WPA2-AES or WPA3, where supported.
- Set a strong Wi-Fi password.
- Keep router firmware updated.
- Disable features such as WPS if they are unnecessary or create additional risk.
- Avoid connecting to unknown Wi-Fi hotspots that imitate trusted networks.
4.7 Keep Software and Devices Updated
Updates often fix security weaknesses. Users should install updates from trusted sources and avoid running unsupported software where possible.
4.8 Avoid Suspicious Links and Attachments
Unexpected messages, urgent warnings, unusual prizes and requests for passwords may be signs of phishing. Verify the source before opening attachments or entering information.
4.9 Use Secure Communication Services
When sending sensitive information, use trusted services with appropriate security protections. Check that a website uses HTTPS, but remember that HTTPS alone does not prove that a website is honest or legitimate.
4.10 Control Access to Network Resources
Only authorised users should receive access to sensitive files and systems. Permissions should be limited to what each user needs to perform their duties. Unused accounts should be disabled when appropriate.
4.11 Back Up Important Information
Regular backups help recover information after accidental deletion, device failure or certain cyberattacks. Important backups should be protected from unauthorised access and kept separate from devices that may be affected by an attack.
| Security Method | Purpose |
|---|---|
| Strong passwords and MFA | Reduce the risk of unauthorised account access. |
| Encryption | Protect the confidentiality of information in transit or storage. |
| Firewall | Control network traffic according to security rules. |
| Security software | Detect and help block malicious software. |
| Software updates | Fix known weaknesses and improve protection. |
| Secure Wi-Fi settings | Reduce unauthorised access to wireless networks. |
| Access controls | Limit resources to authorised users. |
| Backups | Support recovery after data loss or damage. |
5. Class Activity
Activity: Identify and Prevent Network Security Threats
Study each situation and state the possible threat and an appropriate preventive measure.
| Situation | Possible Threat | Suggested Prevention |
|---|---|---|
| A student receives a message asking for their school account password through an unfamiliar link. | Phishing | Do not use the link; verify the request through an official channel. |
| A computer becomes infected after a user installs an unknown application. | Malware | Use trusted software sources and updated security software. |
| An employee needs to access an organisation's internal network from home. | Risk of insecure remote access | Use the organisation's approved secure remote-access method, such as a properly configured VPN. |
| A router still uses its factory administrator password. | Unauthorised access risk | Change the default password and apply secure router settings. |
Students should work in pairs, discuss the situations and present their answers to the class.
6. Summary
Network security protects networks, devices and information against unauthorised access, attacks and disruption. Common threats include malware, phishing, password attacks, eavesdropping, denial-of-service attacks and unsecured Wi-Fi. A Virtual Private Network (VPN) creates an encrypted connection between a device and a VPN endpoint and can support secure remote access. Basic network security measures include strong passwords, multifactor authentication, encryption, firewalls, security updates, secure Wi-Fi settings, access controls and regular backups.
7. Evaluation Questions
- Define network security.
- Explain the three main goals of network security: confidentiality, integrity and availability.
- List five common network security threats.
- What is phishing, and how can users protect themselves against it?
- Explain the meaning of a Virtual Private Network (VPN).
- Describe three uses of VPNs.
- State two advantages and two limitations of VPNs.
- Explain four methods of securing network communications.
8. Assignment
Answer the following questions in your notebook:
- Explain the importance of network security in a school computer laboratory.
- Describe four common network security threats and their possible effects.
- Explain how a VPN works and state three situations in which it may be useful.
- List six measures a school can take to secure its computer network.
- Explain why using a VPN alone cannot guarantee complete online safety.
9. Interactive Revision Quiz
Choose one answer for each question. Click Mark Quiz to check your score, or Reset Quiz to try again.
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