Overview of Network Security

Overview of Network Security - Overview of Network Security...

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Overview of Network Security Dijiang
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2 What is the Problem? 2002 Study by Computer Security Institute 90% of respondents were hacked 80% of those lost money (about $450 million) 75% of those attacks came from across the net Problem seems to be getting worse
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3 What is the problem? Unauthorized access Theft or modification of files Take over machines
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4 Example Threats Trojan Horses Viruses and Worms Denial-of-Service Attacks Buffer Overflow Attacks Spoofing and Man-in-the-middle Attacks
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5 Security Policy Security is a relative term Network security depends on computer security Difficult to assess the costs of a break-in Cost to re-do the work? Cost of liability from harm to others? Indirect costs (competitive advantage) is difficult to calculate?
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6 Security Aspects Data Integrity Is the data still correct? Dat Availability Can we use it when we need it? Data Confidentiality Is it safe from unauthorized access? Privacy Is source of data protected?
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7 Security Policy Responsibilities Accountability Who is responsible for each element of data? How do they track what happens to that data? Authority Who has ultimate control for each data element? How is that control delegated?
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8 Computer Security Identification Authentication Access Risks from Networked Services Clients vs. Servers WWW e-mail FTP, telnet, SMTP, etc.
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9 Encryption One way to protect data that cannot be secured (data traveling across a public network) is to convert the information into a form that is unreadable without some secret. Encryption method should be easy to reverse with the secret and very difficult (impossible??) without the secret.
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Single Key Encryption The data can be processed by a program that uses a shared secret (key) that only sender and receiver know. Cyphertext = encrypt (key, Cleartext)
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Overview of Network Security - Overview of Network Security...

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