IT602 • Wireless and Mobile Computing

Unit 5 Wireless and Network Security

Complete exam-oriented notes on intruders, intrusion detection, password management, malicious software, biometrics, authentication and firewall technologies.

Start Reading
Home › Wireless and Mobile Computing › Unit 5

1. Introduction to Security

Computer and network security protects information, devices and services from unauthorized access, misuse, modification and destruction.

Security Goals

  • Confidentiality: data is available only to authorized users.
  • Integrity: data is not changed without permission.
  • Availability: services remain accessible.
  • Authentication: identity is verified.
  • Non-repudiation: a user cannot deny an action.

2. Intruders

An intruder is a person or program that attempts unauthorized access to a system, network or information.

Types of Intruders

TypeDescriptionExample
MasqueraderOutsider pretending to be an authorized userUsing a stolen password
MisfeasorLegitimate user misusing privilegesEmployee accessing restricted records
Clandestine UserAttacker gaining supervisory control and hiding activityDisabling audit logs

Common Activities

  • Stealing data
  • Changing or deleting information
  • Installing malware
  • Privilege escalation
  • Disrupting services

3. Intrusion Detection System

An Intrusion Detection System monitors host or network activity and identifies suspicious behavior or policy violations.
Network / Host Activity | Data Collection | IDS Analysis | Alert / Report

Types

  • Host-Based IDS: monitors files, logs and processes on one device.
  • Network-Based IDS: monitors packets and network traffic.

Detection Methods

  • Signature based: detects patterns of known attacks.
  • Anomaly based: detects deviation from normal behavior.
MethodAdvantageLimitation
Signature basedAccurate for known attacksMay miss new attacks
Anomaly basedCan identify unknown attacksMay generate false alarms

4. Password Management

Password management includes securely creating, storing, using and changing passwords.

Guidelines

  • Use long and unique passwords
  • Avoid names, dates and common words
  • Use passphrases
  • Enable multi-factor authentication
  • Never share passwords
  • Change compromised passwords immediately

Password Attacks

  • Brute-force attack
  • Dictionary attack
  • Credential stuffing
  • Phishing
  • Keylogging
  • Shoulder surfing
Storage rule: Passwords should be stored as salted hashes, not as plaintext.

5. Malicious Software

Malware is software designed to damage systems, steal information, disrupt services or obtain unauthorized control.
  • Virus
  • Worm
  • Trojan horse
  • Spyware
  • Ransomware
  • Rootkit
  • Adware

6. Computer Virus

A computer virus is malicious code that attaches to a host file or program and spreads when the infected host executes.

Life Cycle

  1. Dormant phase
  2. Propagation phase
  3. Triggering phase
  4. Execution phase

Types

  • File infector virus
  • Boot-sector virus
  • Macro virus
  • Polymorphic virus
  • Multipartite virus

7. Computer Worm

A worm is a self-replicating malicious program that spreads automatically through networks without attaching to a host file.
  • Replicates automatically
  • Consumes bandwidth and resources
  • Exploits network vulnerabilities
  • May install additional malware
  • Can spread rapidly

8. Trojan Horse

A Trojan horse is a malicious program that appears legitimate but performs hidden harmful actions.
  • Steals credentials
  • Creates a backdoor
  • Downloads other malware
  • Monitors user activity
  • Modifies or deletes files
Important: A Trojan generally does not self-replicate and usually depends on user installation.

9. Virus, Worm and Trojan Comparison

FeatureVirusWormTrojan
Needs host fileYesNoNo
Self-replicatesAfter executionYesNo
Automatic spreadLimitedYesNo
User actionOften neededNot alwaysUsually needed
Main techniqueInfects filesUses network weaknessesPretends to be legitimate

10. Biometrics

Biometric authentication verifies identity using measurable physical or behavioral characteristics.

Types

  • Fingerprint
  • Face recognition
  • Iris recognition
  • Retina recognition
  • Voice recognition
  • Signature dynamics
  • Keystroke pattern
Biometric Sample | Feature Extraction | Template Matching | Accept or Reject

Performance Measures

  • FAR: False Acceptance Rate
  • FRR: False Rejection Rate
  • EER: Equal Error Rate

11. Authentication

Authentication verifies the identity of a user, device or system.

Authentication Factors

  • Something you know: password or PIN
  • Something you have: card or phone
  • Something you are: biometric trait
  • Somewhere you are: location
  • Something you do: behavioral pattern

Multi-Factor Authentication

Multi-factor authentication combines two or more independent factors to provide stronger protection.

12. Firewall

A firewall is a hardware or software security system that controls incoming and outgoing traffic according to predefined rules.
Trusted Network | Firewall | Untrusted Internet

Types of Firewalls

TypeWorkingFeature
Packet FilteringChecks addresses, protocol and portsFast and simple
Stateful InspectionTracks active connectionsContext-aware filtering
Application ProxyActs as application intermediaryDeep control
Circuit-Level GatewayValidates sessionsHides internal network
Next-Generation FirewallCombines filtering and threat detectionAdvanced protection

Functions

  • Traffic filtering
  • Access control
  • Network segmentation
  • Logging and monitoring
  • Blocking unauthorized services

Limitations

  • Cannot stop every insider attack
  • Cannot replace antivirus
  • Misconfiguration reduces protection
  • Cannot prevent all social engineering attacks

Unit 5 Summary

  • Intruders attempt unauthorized access or misuse legitimate privileges.
  • IDS detects suspicious host and network activity.
  • Password management reduces account compromise.
  • Viruses attach to files, worms self-replicate and Trojans disguise themselves.
  • Biometric systems use physical or behavioral features.
  • Authentication verifies identity using one or more factors.
  • Firewalls control traffic according to security policies.

Important RGPV Exam Questions

Long Answer Questions

  1. Define intruder and explain its types.
  2. Explain intrusion detection systems and their functions.
  3. Compare host-based and network-based IDS.
  4. Compare signature-based and anomaly-based detection.
  5. Explain password management and password attacks.
  6. Explain virus and its life cycle.
  7. Explain worm and Trojan horse.
  8. Differentiate virus, worm and Trojan horse.
  9. Explain biometric authentication and performance measures.
  10. Explain authentication factors and MFA.
  11. Define firewall and explain its types.
  12. Explain firewall functions and limitations.

Short Answer Questions

  1. Define masquerader.
  2. What is a misfeasor?
  3. Expand IDS.
  4. What is anomaly detection?
  5. Define brute-force attack.
  6. What is a Trojan horse?
  7. Expand FAR and FRR.
  8. What is packet filtering?
Exam Strategy: Use comparison tables for malware and IDS methods. Draw IDS, biometric and firewall diagrams.

Download Study Resources

Complete Notes PDF

Printable notes will be uploaded soon.

Coming Soon

Important Questions

Question bank will be available soon.

Coming Soon

PYQ Analysis

Previous-year analysis will be added soon.

Coming Soon

Frequently Asked Questions

An intruder is a person or program that attempts unauthorized access or misuse of a computer system.
An IDS monitors host or network activity and generates alerts for suspicious behavior.
A virus normally attaches to a host file, while a worm is independent and can spread automatically.
It verifies identity using physical or behavioral characteristics.
A firewall controls network traffic and blocks communication that violates security rules.