UNRAVELLING THE NET

Greg DurkinMount Waverley Secondary College

Examining SD U402

Networking Fundamentals Analysing Networks for Security &

Reliability Passive methods Active methods

Quality of Network Solutions Ethical Dilemmas for Network Users

Networking Fundamentals

Of course, it all begins with the OSI model

Layer 1: the Physical Layer ----------- No, no, no – Wait a minute

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The OSI Game

Design a networking system using OSI as a guideline

Start with Layer 1 – How will you signal? Smoke, can & string, flags, garden

hoses? What else will you need to carry and

effect signals? How do you turn signals into messages?

The OSI Game

Now, move up to Layer 2: How will you get somebody’s attention? Deal with conflicts? Identify sender and receiver?

Layer 3: How will you get the signals to people in

other groups? Who decides where a message goes? How do you decide how a messages

travels?

OSI Layer 1 in Flags

Layer 1 – Let’s use flags. To be visible over a distance, we will

need some towers. And, as an unavoidable part of the

system, some people to wave the flags:

OSI Layer 1 in Flags

OSI Layer 1 in Flags

OSI Layer 2 in Flags

OSI Layer 2 in Flags

OSI Layer 2 in Flags

OSI Layer 2 in Flags

OSI Layer 2 in Flags

OSI Layer 2 in Flags

OSI Layer 3 in Flags

OSI Layer 3 in Flags

OSI Layer Game

Challenge students to simulate all layers

Let them research the functions of the layers and represent them in some analogue of electronic LAN operation.

FORMS OF NETWORK ANALYSIS

Passive Network Analysis

Why perform an analysis No system is perfect – what defects are here? Parts do fail Software upgrades can have flow-on consequences

Regular system audits Base Line Measurement Physical condition checks Event monitoring

Reading system logs Error logs Security event logs

Active Network Analysis

ICMP Echo Request (Ping)

Active Network Analysis Traceroute

Active Network Analysis Traceroute

Other Network Analysis Tools WireShark (formerly Ethereal) Etherape nMap Port Mappers PenTesting

Quality of Network Solutions Does it solve the original problem?

For the client For the end user What led to the demand?

Examine old records Interview staff

Have the trigger conditions changed?

QUALITY OF NETWORK SOLUTIONS

Quality of Network Solutions Is the solution acceptable

To the client Frank discussion Survey questions

To the end user Anonymous poll Survey of selected users

When Good Networks Go Bad

Disconnected or shorted coaxial network “Divide and conquer” binary search

Ethernet access port loop Collisions on a switch-based network “Smart Switch” to isolate and report faults

Slow network Use network analyser to measure traffic Students Skype with each other? Network gaming 650 new Wi-Fi users?

ETHICAL QUESTIONS

Ethical Questions

Copyright – as always Content management

Improper / inappropriate Language, racial, gender biased etc Explicit imagery Time-wasting

Unsafe / inconvenient Executable – (Student’s media server)! Compressed – (Unknown content) Deliberately hidden (changed extension)

Ethical Questions

Who makes the decision? One student’s “manga artwork” is

another student’s “comic book” Students need to learn responsibility Access restriction = restricted rights?

Ethics of monitoring User’s right to privacy & respect Employer’s right to productivity Employer’s obligation to respect content

for all

Locating Resources

www.gdurkin.com for all materials Thank you for your attendance Questions?