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A SEMINAR

ON

BY

ROHIT KAUL CS BITSPILANI

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AGENDA

•Introduction to Computer Networks

•Uses and types

•LANs , WANs , MANs

•Protocols

•Network Security….its need

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CONTINUED..

•Security Areas…….•Modes of attack …..•Safeguarding the systems..•Firewalls and other methods•Network Security.. a Hacker’s perspective

•Summary and conclusions...

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COMPUTER NETWORK ????•Simply an interconnected collection of autonomous computers...•Internet and WWW not networks!!!

•Distributed system

USES•Primarily resource sharing….

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TYPES

•LANs , MANs , WANs , Internet

PROTOCOLS•To reduce design complexity most networks are organised as layers…

•no of layers,names,contents and functions are network specific…..

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Layer 5

Layer 3

Layer 2

Layer 1

Layer 5

Layer 4 Layer 4

Layer 3

Layer 2

Layer 1

Physical layer

Host 1 Host 2

Layern

protocol

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•Infact a protocol is an agreement between the communicating parties on how communication is to proceed…..

•An analogy..

•Application layer,presentation,session,transport,network,datalink,physical layers…..

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SECURITY-ISSUES

•NEED

•4 INTERWINED AREAS...

NETWORKING

PRIVACYAUTHENTICATION

INTEGRITY NON REPUDIATION

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•PRIVACY

•Has to do with keeping info out of the hands of unauthorized users

•Encryption/Decryption

•Secret-key encryption/decryption

•public-key encryption/decryption

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SECRET KEY METHOD

ADV/DISADV

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PUBLIC KEY METHOD (eg RSA)

ADV/DISADV

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•Authentication deals with whom u r talking to before revealing sensitive info

•Integrity control…..no manipulation in data { message received = message sent}

•Non repudiations …no impersonification

•( seeming sender=actual sender )

DIGITAL SIGNATURE

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SIGNING THE DOCUMENT

HOW DOES IT PRESERVE ALL 3?

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UNDER ATTACK!!!

•Denial Of Service (DOS)

mail bombing

spam relaying

smurfing

•Distributed Denial Of Service (DDOS)

•Intrusion attacks

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•IP spoofing

•Malacious programs/scripts

• viruses and worms

• trojans

• vandals

and many more……..

16Denial of Service Loss of Integrity

BankCustomer

Deposit $1000 Deposit $ 100

Security Threats

Loss of Privacy

m-y-p-a-s-s-w-o-r-d d-a-n

telnet company.orgusername: danpassword:

Impersonation

I’m Bob.Send Me All Corporate

Correspondencewith Cisco.

Bob

CPUCPU

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Protection Against Attacks

Against DOS/DDOS

•Simple call to perpetrator’s ISP•Configure procmail/sendmail

•Use spamassassin

Against intrusion

Encryption algorithms

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Configure a Firewall….

What is a FIREWALL????

Analogy with non computer world!!

Basically a shield which protects systems from unreliable sources on the internet.

…it is a utility,listens to all the ports on the system to open a connection,if detects ..reacts acc to predefined rules.

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•Allows only selected packets <pkt filter>….

•General Methods•Updating through patches,virus detection,password cracks,port scanners. etc•Shifting from windows to LINUX/UNIX

•Ckt gateways and relays...

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IP ADDRESSES…

OUR IDENTITY ON THE NET…

32 bit, written normally as 4 decimal nos of 8 bit each < dotted-decimal notation>,,,eg 202.34.12.23

concepts of classes,netmask,subnetmask other notations,etc etc

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FINDING OUT IP OF UR SYSTEM.?.

Connect to internet,launch MSDOSType netstat -n at the prompt

Active conections:

proto local address state

TCP 203.94.253.183:1025 ESTABLISHED

Ping,netstat,traceroute,WHOIS

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FINDING IP OF A REMOTE SYSTEM

•Through instant messaging softwares

•Through HTTP and scripts

•Through internet relay Chat IRC

•Through e-mail headers

Most common method of getting ips is thru instant mesg softwares like MSN,ICQ,Y

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ICQ

Xx.xx.xx.xx<---------------->yy.yy.yy.yy

MSN

Xx.xx.xx.xx----MSN server--yy.yy.yy.yy

Transfer file,and use netstat….

Prevention..don’t accept file transfer,use wingate???

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IPS BY STUDYING EMAIL HEADERS

Return-path:<simran_8@hotmail.com>

received:from hotmail.com by jammu.bsnl.net.in

(8.9.1/1.1.20.3/5jun04-12:30p.m.)

-----------------------------------------------------

X-originating Ip:[202.15.109.174]

from:simran”<simran_8@hotmail.com>

To:rohit_bits@rediffmail.com

-----------------------

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GETTING IP USING IRC

/Whois nicknameofthevictim

/whois swordfish

swordfish is rohit@203.23.254.71*rohit koul

swordfish on #chatterz

swordfish using irc.net GlobalNAPs Quincy,MA

swordfish has been idle since………

swordfish…Endof/WHOIS list

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I have the IP..so what???

First step sor any hacking attack…..

All those attacks discussed before can be implemented….

Apart from getting ip…other imp things..cracking softwares,banner grabbing,breaking encryptions,fingerprinting etc but...

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Summary and conclusions

•U c I have left a lot untouched…

•hash functions,DES,blow fish,detailed desciption of RSA ,hacking methods etc

•it is nearly impossible to configure a firewall or create a network that’s 100% fool-proof without compromising on the services to b offered

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Security Objective: Balance Business Needs with Risks

Access SecurityAuthentication

Authorization

Accounting

Assurance

Confidentiality

Data Integrity

Policy ManagementPolicy Management

Connectivity

Performance

Ease of Use

Manageability

Availability

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ANY QUESTIONS?????