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
--------
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?