“Network Security”

1. “Network Security” Introduction

2. My Introduction • Obaid Ullah Owais Khan • B.E (I.T) – Hamdard University(2003), Karachi • Network Engineer, Pakistan Standards & Quality Control Authority (PSQCA), Government of Pakistan • E-mail: o.owais@fuuast.edu.pk

3. Course Overview • Course: Network Security • Time: 06:00 – 07:00 pm on Thursday, Friday & Saturday • Classroom: Lab 2 , FUUAST • Prerequisite: Computer Networks, Discrete Mathematics.

4. Resources Textbook • Network Security Essentials: Applications and Standards, 4th ed., by William Stallings, Pearson Education, Inc., 2011. • Cryptography and Network Security: Principles and Practice, Fifth Edition, by William Stallings, Prentice-Hall, 2011 • Internet Searching

5. Semester Pattern • Lectures Slide • Book • Research Papers • Presentations • Quiz • Mid-term and Final exams

6. Grading Policy (Tentative) grading policy • Quiz (best 1 out of 2) : 10% • Attendance and class participation: 10% • Research paper and Presentation: 10% • Midterm : 20% • Final exams: 50%

7. Course Outline • Introduction • Cryptography • Symmetric encryption and message confidentiality • Public-key cryptography and message authentication • Network security applications • Key distribution and user authentication • Transport-level security • Wireless network security • Electronic mail security • IP security • System security • Intruders • Malicious software • Firewalls

8. Topical Surveys • We will try to read surveys in network security-related topics, e.g.: • Demonstration on how to use a network security tool • Comparison of security standards or algorithms • Potential security weakness in systems, and possible solutions or countermeasures • …

9. Computer Security • the protection afforded to an automated information system in order to attain the applicable objectives of preserving the integrity, availability and confidentiality of information system resources (includes hardware, software, firmware, information/data, and telecommunications) [NIST95]

10. Key Security Concepts

11. Levels of Impact • can define 3 levels of impact from a security breach • Low • effectiveness of the functions is noticeably reduced • minor damage to organizational assets and financial loss • Moderate • effectiveness of the functions is significantly reduced • major damage to organizational assets and financial loss • High • is not able to perform one or more of its primary functions • major damage to organizational assets and financial loss

12. Computer Security Challenges not simple must consider potential attacks involve algorithms and secret info must decide where to deploy mechanisms battle of wits between attacker / admin requires regular monitoring regarded as impediment to using system

13. OSI Security Architecture • ITU-T X.800 “Security Architecture for OSI” • defines a systematic way of defining and providing security requirements

14. Aspects of Security • consider 3 aspects of information security: • security attack • security mechanism • security service • note terms • threat – a potential for violation of security • attack – an assault on system security, a deliberate attempt to evade security services

15. Passive Attacks

16. Passive Attacks (2)Traffic Analysis

17. Passive attacks do not affect system resources • Eavesdropping, monitoring • Two types of passive attacks • Release of message contents • Traffic analysis • Passive attacks are very difficult to detect • Message transmission apparently normal • No alteration of the data • Emphasis on prevention rather than detection • By means of encryption

18. Active Attacks (1)Masquerade

19. Active Attacks (2)Replay

20. Active Attacks (3)Modification of Messages

21. Active Attacks (4)Denial of Service

22. Active attacks try to alter system resources or affect their operation • Modification of data, or creation of false data • Four categories • Masquerade • Replay • Modification of messages • Denial of service: preventing normal use • A specific target or entire network • Difficult to prevent • The goal is to detect and recover

23. Security Services (X.800) • Authentication - assurance that communicating entity is the one claimed • have both peer-entity & data origin authentication • Access Control - prevention of the unauthorized use of a resource • Data Confidentiality –protection of data from unauthorized disclosure • Data Integrity - assurance that data received is as sent by an authorized entity • Non-Repudiation - protection against denial by one of the parties in a communication • Availability – resource accessible/usable

24. Security Mechanism • feature designed to detect, prevent, or recover from a security attack • no single mechanism that will support all services required • however one particular element underlies many of the security mechanisms in use: • cryptographic techniques

25. Model for Network Security

26. Model for Network Security • using this model requires us to: • design a suitable algorithm for the security transformation • generate the secret information (keys) used by the algorithm • develop methods to distribute and share the secret information • specify a protocol enabling the principals to use the transformation and secret information for a security service

27. Model for Network Access Security

28. Model for Network Access Security • using this model requires us to: • select appropriate gatekeeper functions to identify users • implement security controls to ensure only authorised users access designated information or resources