Introduction to Network Security-Network Security-Lecture Slides, Slides of Cryptography and System Security

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CE^4608 ‐

Network^ Security (Lecture^ 1)

Agenda

Course^ Contents Prerequisite^ &^

Text^ Book

What^ is^ Security? Network^ Security Aspects^ of^ Security Threat^ and^ Attack Active^ vs.^ Passive

Attack

Security^ Services Encryption? Course^ Objective Grading^ and^ Policies

Prerequisite

&^ Textbook

“Cryptography

and^ Network

Security^ Principles

and^ Practices”,

Fourth^ Edition,

by^ William^ stalling

Reference

books

Cryptography

and^ Network

Security”^ by

Behrouz^ A^ Forouzan “Introduction

to^ Network^ Security”

by^ Neal

Krawets. “Introduction

to^ Cryptography

and^ Network

Security”^ by^ Sunil

Gupta

Network^ Security?

Network security is the security measures thatare^ needed

to^ protect

data^ during

their

transmission.

Aspects^ of

Security

Security^ attack:

Any^ action^ that

compromises^ the

security^ of^ information

owned^ by^ an^ organization.

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^ the^ data^ processing

systems^ and^ the

information

transfers^ of^ an^

organization. Designed to counter^ security^ attacks.

Interruption

Destroy^ hardware

(cutting^ fiber)^

or^ software

Corrupt^ packets

in^ transit

Denial^ of^ service

(DoS):Crashing the serverOverwhelm the server^ (use^ up^ its

resource) S^

R

Modification

Stop^ the^ flow

of^ the^ message.

Delay^ and^ optionally

modify^ the^ message

Release^ the

message^ again. S

R Perpetrator

Fabrication

Unauthorized

assumption^

of^ other’s

identity Generate^ and

distribute^ objects

under

this^ identity S^

R Masquerader:^ from

S

Passive^ Attacks

Passive^ attacks

eavesdrop,

or^ monitor,

transmission. Goal:^ To^ obtain

transmitted

information.

^2 Types^ of

passive^ attacks.

Passive^ Attack

Types

Release^ of^ contents:

A^ telephone^ conversation,

an

electronic^ mail

message,^ or^ confidential

information.

Traffic^ analysis:

Using^ the^ location

and^ identities^

of

hosts^ and^ the^ frequency

and^ length^ of^ messages

to

determine^ the^

type^ of^ communication

taking^ place.

Passive^ attacks

are^ difficult^ to

detect^ since^ they

do^ not

involve^ any^ alteration

of^ data.

Active^ Attacks

Types

Masquerade^ takes

place^ when^ one^ entity

pretends^ to^ be^ a different^ entity.^ This^ form^ usually

includes^ one^ of^ the^ other

forms^ of^ active^ attack. Replay^ involves

the^ passive^ capture

of^ a^ data^ unit^ and

its

subsequent^ retransmission

to^ produce^ an^ unauthorized

effect.

Modification^ occurs

when^ an^ unauthorized

party^ gains^ access to^ and^ tampers^ with

an^ asset. This is an attack on^ integrity. Denial^ of^ service

prevents^ or^ slow

down^ the^ normal

use^ or

management^ of^ communications

facilities.

Security^ Services

(CAIN2A)

Confidentiality^ is^ the

protection^ of^ transmitted

data^ from^ passive^ attacks. Authentication^ is^ concerned

with^ assuring^ that^ a^

communication^ is authentic. Integrity^ assures^ that

messages^ are^ received

as^ sent. A^ connection‐oriented

integrity^ service^ should

assure^ that^ there^ are

no

duplicates,^ insertions,

deletions,^ modifications,

reordering,^ or^ replays. A^ connectionless^ integrity

service^ deals^ only^ with

an^ individual message. Non‐repudiation^ prevents

either^ the^ sender^ or

receiver^ from^ denying

a

transmitted^ message. Access^ Control^ is^ the

ability^ to^ limit^ and^ control

the^ access^ to^ host^ systems and^ applications^ via^ communications

links. Availability^ is^ the^ ability

to^ prevent^ the^ loss^ or

a^ reduction^ in^ availability

of

elements^ of^ a^ distributed

system.