1. dibyajit dash@PIET,ORISSA
Computer Security
Hacking
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2. what exactly HACKING is ?
->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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3. Internet Protocol Stack
BitTorrent
SMTP
HTTP
Application Layer
RTSP
UDP
TCP
Transport Layer IP
Network Layer
Ethernet
802.11(b, a, g) / WiFi
Link Layer
Physical Layer
Cables
Fiber Optics
Radio
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4. dibyajit dash@PIET,ORISSA
SMTP
->SMTP used to send from sender to recipient’s 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 recipient sender SMTP SMTP POP3
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5. dibyajit dash@PIET,ORISSA
Electronic Mail
Three major components:
• user agents
• mail servers
• simple mail transfer protocol:
SMTP
User Agent
• a.k.a. “mail reader”
• composing, editing, reading
mail messages
• e.g., pine, Outlook, elm,
Thunderbird
• outgoing, incoming messages
stored on server
SMTP
user agent
Mail server
user agent
Mail server
user agent
user agent
Mail server
user agent
user agent
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6. Electronic Mail: mail servers
Mail Servers • mailbox contains incoming messages for user • message queue of outgoing (to be sent) mail messages • SMTP protocol between mail servers to send messages – client: sending mail server – “server”: receiving mail server
SMTP
Mail server
Mail server
Mail server
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7. 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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8. dibyajit dash@PIET,ORISSA
Mail message format
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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9. More mail access protocols
• SMTP: delivery/storage to receiver’s 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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10. dibyajit dash@PIET,ORISSA
What is Security?
Security is the protection of assets. The three main aspects are:
prevention
detection
re-action
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11. Some differences between traditional security and information security
Information can be stolen - but you still have it
Confidential information may be copied and sold - but the theft might not be detected
The criminals may be on the other side of the world
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12. dibyajit dash@PIET,ORISSA
Computer Security deals with the prevention and detection of unauthorised actions by users of a computer system.
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13. dibyajit dash@PIET,ORISSA
There is no single definition of security
What features should a computer security system provide?
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14. dibyajit dash@PIET,ORISSA
Confidentiality
The prevention of unauthorized disclosure of information.
Confidentiality is keeping information secret or private.
Confidentiality might be important for military, business or personal reasons.
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15. dibyajit dash@PIET,ORISSA
Security systems
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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16. dibyajit dash@PIET,ORISSA
Risk Analysis
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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17. Designing a Security System
There are a number of design considerations:
Does the system focus on the data, operations or the users of the system?
What level should the security system operate from? Should it be at the level of hardware, operating system or 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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18. dibyajit dash@PIET,ORISSA
Summary
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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19. dibyajit dash@PIET,ORISSA
Thank You…
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20. dibyajit dash@PIET,ORISSA