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Network Security 1st Lecture

This document provides information about a network security course, including the instructor's contact details, course schedule, grading policy, reference materials, expectations, and course contents. The course will cover topics such as cryptography, network security applications, system security, and intrusion detection. Students will learn about network security principles, cryptography, authentication and encryption techniques, and security practices and applications.

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Network Security Tariq Ahmed Dr. A. Q. Khan Institute of Information Technology and Computer sciences(KICSIT) mrbokhari2000@yahoo.com  
• Instructor: - Tariq Ahmed • Tel: 051 9285342 • Email: mrbokhari2000@yahoo.com Course Staff
• Lectures - Wednesday: 4:00 - 7:00 p.m. • Assignments - • Quizes - • Midterm exam - • Final exam -   Course Schedule
• Assignments 10% – Late assignments are not accepted • Quizes 10% • Midterm exam 20% • Final exam 60% Grading Policy
Academic Honesty • Your work in this class must be your own • If students are found to have collaborated excessively or to have cheated (e.g. by copying or sharing answers during an examination), all involved will at a minimum receive grades of 0 for the first infraction • Further infractions will result in failure in the course.
Course Material Reference books – No single textbook covers the whole course! • Lot of research papers! – Many will be made available • RFCs and Internet drafts – Related to Network security protocols • Web resources – Tutorials, white papers, reports, etc.
Course Information • Pre-requisites – Computer Networks course • You are assumed to have good knowledge of TCP/IP protocol suite – Operating Systems – Basic understanding of programming languages
Course Contents • Introduction to network security • I. CRYPTOGRAPHY – Symmetric Encryption and Message Confidentiality – Public-Key Cryptography and Message Authentication • II. NETWORK SECURITY APPLICATIONS – Authentication Applications (Kerberos, X.509) – Electronic Mail Security (PGP, S/MIME) – IP Security (IPSec, AH, ESP, IKE) – Web Security (SSL, TLS, SET) – Network Management Security (SNMP)
Course Contents • III. SYSTEM SECURITY – Intruders and intrusion detection – Malicious Software (viruses) – Firewalls and trusted systems – Operating System Security
Textbooks • One of the following three books is required for this course: • William Stallings, Network Security Essentials • William Stallings, Cryptography and Network Security: Principles and Practice
Textbooks • Ed Skoudis, Counter Hack: A Step by Step Guide to Computer Attacks and Defenses
Expectations What do you want (or expect) to learn from this class ?
Expectations • This class IS about … – Network security principles and concepts – Cryptography, its use, principles and major algorithms – Message authentication and encryption techniques – Security of network “system” – Operating system security – Security practices and applications
Expectations • This class IS NOT about … – Survey of existing protocol standards – Survey of loopholes in current protocols – How to hack the network of KICSIT! – Tools and tips to breach Internet security – How you can become a good hacker …
Expectations We will learn Why and How networks are made secure
Outline • Attacks, services and mechanisms • Security attacks • Security services • Methods of Defense • A model for Internetwork Security • Internet standards and RFCs
Background • Information Security requirements have changed in recent times • Traditionally provided by physical and administrative mechanisms • Computer use requires automated tools to protect files and other stored information • Use of networks and communications links requires measures to protect data during transmission
Definitions • Computer Security - generic name for the collection of tools designed to protect data and to thwart hackers • Network Security - measures to protect data during their transmission • Internet Security - measures to protect data during their transmission over a collection of interconnected networks
Aim of this Course • Our focus is on internet security • Consists of measures to deter, prevent, detect, and correct security violations that involve the transmission of information • Requirements seem straightforward, but the mechanisms used to meet them can be quite complex …
Services, Mechanisms, Attacks • Need systematic way to define requirements • Consider three aspects of information security: – security attack – security mechanism – security service • Consider in reverse order
Security Service • Is something that enhances the security of the data processing systems and the information transfers of an organization • Intended to counter security attacks • Make use of one or more security mechanisms to provide the service • Replicate functions normally associated with physical documents e.g. – have signatures or dates – need protection from disclosure, tampering, or destruction – be notarized or witnessed – be recorded or licensed
Security Mechanism • A mechanism that is designed to detect, prevent, or recover from a security attack • No single mechanism that will support all functions required • However one particular element underlies many of the security mechanisms in use: cryptographic techniques • Hence our focus is on this area
Security Attack • Any action that compromises the security of information owned by an organization • Information security is about how to prevent attacks, or failing that, to detect attacks on information-based systems • Have a wide range of attacks • Can focus on generic types of attacks – Note: often threat & attack mean same
Security Attacks
Security Attacks • Interruption: This is an attack on availability • Interception: This is an attack on confidentiality • Modification: This is an attack on integrity • Fabrication: This is an attack on authenticity
Security Goals
Summary: Attacks, Services and Mechanisms • Security Attack: Any action that compromises the security of information. • Security Mechanism: A mechanism that is designed to detect, prevent, or recover from a security attack. • Security Service: A service that enhances the security of data processing systems and information transfers. A security service makes use of one or more security mechanisms
OSI Security Architecture • ITU-T X.800 Security Architecture for OSI • Defines a systematic way of defining and providing security requirements • For us it provides a useful, if abstract, overview of concepts we will study
Security Services • X.800 defines it as: a service provided by a protocol layer of communicating open systems, which ensures adequate security of the systems or of data transfers • RFC 2828 defines it as: a processing or communication service provided by a system to give a specific kind of protection to system resources
Security Services (X.800) • X.800 defines security services in 5 major categories – Authentication - assurance that the communicating entity is the one claimed – 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
Security Services • Confidentiality (privacy) • Authentication (who created or sent the data) • Integrity (has not been altered) • Non-repudiation (the order is final) • Access control (prevent misuse of resources) • Availability (permanence, non-erasure) – Denial of Service Attacks – Virus that deletes files
Security Mechanisms (X.800) • Specific security mechanisms: – Encipherment: Converting data into form that is not readable – Digital signatures: To check authenticity and integrity of data – Access controls: Enforcing access rights to resources – Data integrity – Authentication exchange – Traffic padding: Insertion of bits to frustrate traffic analysis – Routing control: Selection of secure routes – Notarization: Use of trusted third party for data exchange
Security Mechanisms (X.800) • Pervasive security mechanisms: – trusted functionality: percieved to be correct with respect to some criteria – security labels: – event detection: detection of security relevant events – security audit trails: – security recovery:
Classify Security Attacks as • Passive attacks - eavesdropping on, or monitoring of, transmissions to: – obtain message contents, or – monitor traffic flows • Active attacks – modification of data stream to: – masquerade of one entity as some other – replay previous messages – modify messages in transit – denial of service
Passive Attacks: Release of Message Contents
Passive Attacks: Traffic Analysis
Active Attacks: Masquerade
Active Attacks: Replay
Active Attacks: Modification of Messages
Active Attacks: Denial of Service
Model for Network Security
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
Model for Network Access Security
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 • Trusted computer systems can be used to implement this model
Methods of Defense • Encryption • Software Controls (access limitations in a data base, in operating system protect each user from other users) • Hardware Controls (smartcard) • Policies (frequent changes of passwords) • Physical Controls
Internet standards and RFCs • The Internet society – Internet Architecture Board (IAB) – Internet Engineering Task Force (IETF) – Internet Engineering Steering Group (IESG)
Summary • Have considered: – computer, network, internet security def’s – security services, mechanisms, attacks – X.800 standard – models for network (access) security