Network systems security by mort anvari lecture1

8/24/2004 2About the Course  A grad-level seminar course focusing on basics and issues in network security  First half will be lectures about elements of network security, cryptography

Introduction to Network Systems Security

Mort Anvari

8/24/2004 2

About the Course

 A grad-level seminar course focusing on basics and issues in network security

 First half will be lectures about elements

of network security, cryptography

backgrounds, and introduction to

network security designs

 Second half will be your chance to

present what you have learned from key research papers

Why Should You Take This

Course

 Security is an increasingly important

issue

 You want to have basic knowledge

about network security

 You can learn latest attacks and newest skills to counter those attacks

 You have a chance to implement the

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Your Best Strategy

 Come to every lecture to learn basic

security problems and skills to counter

them

 Keep yourself exposed to articles related

to network security to collect project ideas

 Read each assigned paper and write good summary for each paper

 Do not wait till last minute to prepare for exam or work on project

 Enjoy the fun!

What Can Go Wrong…

 …when your computer y receive or

is waiting for a message m?

m

?

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Message Modification

 Adversary A can arbitrarily modify

the content of m to become m’

m

m’

A

Message Insertion

 Adversary A can arbitrarily fabricate a

message m, pretending that m was sent

by x

m

src: x dst: y

A

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Message Replay

 Adversary A can replay a message m

that has been sent earlier by x and

Denial-of-Service Attack

 Adversary A can send huge amount of

messages to y to block m from arriving

 Message insertion

 Message replay

 Denial-of-Service attack

Network Security Services

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Confidentiality

 Keep message known only to the

receiver and secret to anyone else

 Counter message interception

 When receiver receives message m,

receiver can verify m is intact after sent

by sender

 Counter message modification

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Authentication

 When receiver receives message m,

receiver can verify m is indeed sent by the sender recorded in m

 Counter message insertion

 When receiver receives message m,

receiver can verify m is not a message that was sent and received before

 Counter message replay

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Availability

 Property of a system or a resource

being accessible and usable upon

demand by an authorized entity

 Counter denial-of-service attack

 Users cannot access resources and data

to which they don’t have access rights

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Non-repudiation

 When receiver receives message m,

receiver gets proof that sender of m

ever sent m

 Receiver of m can show proof to

third-party so that sender of m cannot

repudiate

 Identity of sender is hidden from

receiver

 When receiver receives message m,

receiver has no clue about sender of m

 Disallow unauthorized access to local

system resource and sensitive data

…But Hard To Achieve

 Many layers in network architecture

 Many different media of network

connection

 Adversary’s location hard to determine

 New attacks keep emerging

 Cryptographic overhead

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Next Class

 Formal specification and verification of network protocols

 Network security tools to counter the

effects of adversary actions