“Network Security” Introduction

My Introduction Obaid Ullah Owais Khan Obaid Ullah Owais Khan B.E (I.T) – Hamdard University(2003), Karachi B.E (I.T) – Hamdard University(2003), Karachi Network Engineer, Pakistan Standards & Quality Control Authority (PSQCA), Government of Pakistan Network Engineer, Pakistan Standards & Quality Control Authority (PSQCA), Government of Pakistan

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

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

Semester Pattern  Lectures Slide  Book  Research Papers  Presentations  Quiz  Mid-term and Final exams

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%

Course Outline Introduction Introduction Cryptography Cryptography Symmetric encryption and message confidentialitySymmetric encryption and message confidentiality Public-key cryptography and message authenticationPublic-key cryptography and message authentication Network security applications Network security applications Key distribution and user authenticationKey distribution and user authentication Transport-level securityTransport-level security Wireless network securityWireless network security Electronic mail securityElectronic mail security IP securityIP security System security System security IntrudersIntruders Malicious softwareMalicious software FirewallsFirewalls

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

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]

Key Security Concepts

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

Computer Security Challenges 1. not simple 2. must consider potential attacks 3. involve algorithms and secret info 4. must decide where to deploy mechanisms 5. battle of wits between attacker / admin 6. requires regular monitoring 7. regarded as impediment to using system

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

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

Passive Attacks

Passive Attacks (2) Traffic Analysis

 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

Active Attacks (1) Masquerade

Active Attacks (2) Replay

Active Attacks (3) Modification of Messages

Active Attacks (4) Denial of Service

 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

Security Services (X.800)  Authentication - assurance that communicating entity is the one claimed have both peer-entity & data origin authentication 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

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 cryptographic techniques

Model for Network Security

 using this model requires us to: 1. design a suitable algorithm for the security transformation 2. generate the secret information (keys) used by the algorithm 3. develop methods to distribute and share the secret information 4. specify a protocol enabling the principals to use the transformation and secret information for a security service

Model for Network Access Security

 using this model requires us to: 1. select appropriate gatekeeper functions to identify users 2. implement security controls to ensure only authorised users access designated information or resources