computer security& email hacking

8/7/2019 Computer Security& Email Hacking

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dibyajit dash@PIET,ORISSA


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->Hacking is a process to bypass the security

mechanisms of an information system or

network. These are two types:-

Local hacking:Local hacking is done in local area where we physical access ,like through

printer etc.

Remote hacking:Remote hacking is done remotely by taking advantages of the vulnerability of

the target system.



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Application Layer

Transport Layer

Network Layer

Link Layer

Physical Layer

SMTP HTTPBitTorrent

TCP UDP

IP

Ethernet 802.11(b, a, g) / WiFi

Cables Fiber Optics Radio

RTSP



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->SMTP used to send email from sender to

recipients mail server

->Then use POP3, IMAP or

HTTP (Web mail)

to get messages from server

->As with many application protocols, SMTP

commands are human readable recipientsender

SMTP SMTP

POP3



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Electronic Mail

Three major components: user agents

mail servers

simple mail transfer protocol:

SMTPUser Agent a.k.a. mail reader

composing, editing, reading

mail messages

e.g., pine, Outlook, elm,Thunderbird

outgoing, incoming messages

stored on server

SMTP

SMTP

SMTP

Mail

server

Mail

server

Mail

server

user

agent

user

agent

user

agent

user

agent

user agentuser agent



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Mail Servers

mailbox contains incoming

messages for user

message queue of outgoing(to be sent) mail messages

SMTP protocol between mail

servers to send emailmessages

client: sending mail server

server: receiving mail

server

SMTP

SMTP

SMTP

Mail

server

Mail

server

Mail

server



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Sending Server to Receiving Server

three phases of transfer

handshaking (greeting)

transfer of messages

closure command/response interaction

commands: ASCII text: HELO, MAIL, RCPT, DATA,

QUIT, etc.

response: status code and phrase

messages must be in 7-bit ASCII



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RFC 822: standard for text

message format:

header lines, e.g.,

To: From:

Subject:

body the message, ASCII

characters only

blank line

header

body



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SMTP: delivery/storage to receivers server

Mail access protocol: retrieval from server

POP: Post Office Protocol [RFC 1939] authorization (agent server) and download

IMAP: Internet Mail Access Protocol [RFC 1730]

more features (more complex) manipulation of stored messages on server

HTTP: Hotmail , Yahoo! Mail, etc.



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Security is the protection of assets. The threemain aspects are:

prevention

detection

re-action



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Computer Security

deals with theprevention and

detection of

unauthorised actions by

users of a computer

system.



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There is no single definition

of security

What features should acomputer security system

provide?



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Confidentiality

The prevention of unauthorized disclosure of

information.

Confidentiality is keeping information secretor private.

Confidentiality might be important for

military, business or personal reasons.



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A security system is not just a computer

package. It also requires security conscious

personnel who respect the procedures and

their role in the system.

Conversely, a good security system should not

rely on personnel having security expertise.



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The disadvantages of a security system are

that they are time-consuming, costly, and

impede management and smooth running of

the organization.

Risk analysis is the study of the cost of a

particular system against the benefits of the

system.



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There are a number of design considerations:

Does the system focus on the data, operations or theusers of the system?

What level should the security system operate from?Should it be at the level of hardware, operating systemor applications package?

Should it be simple or sophisticated?

In a distributed system, should the security be

centralised or spread? How do you secure the levels below the level of the

security system?



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By now you should have some idea about

Why we need computer security (prevention,detection and re-action)

What a computer security system does(confidentiality, integrity, availability, non-repudiation, authentication, access control,

accountability) What computer security exerts do (design,

implement and evaluate security systems)



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