SIT202 Computer Networks Assignment 3 Complete Solution

Question: #8901

SIT202 Computer Networks Assignment 3

This assignment is worth 10% of your final unit grade.
Due on Sept 30, 2015 (9:00 am)
Total: 30 points
This assignment is designed to test your understanding of computer networks through problem solving, literature study, simple analysis and problem solving.

IMPORTANT:
Assignment Rules and Submission Policy
• This assignment is an individual assignment. Discussions are encouraged but copying/plagiarism is not permitted and will be penalized according to university and faculty guidelines.
• It should be completed in its entirety (i.e., all questions must be attempted.)
• This assignment is marked based on the assignment and rubric requirements.
• You are allowed to use up to 6 typed pages to write your ass2 assignment (including references). All margins must be no less than 2 centimeters; a Times New Roman 12 point font and only black color can be used. Oversized assignments will be penalized.
• The submission date for the assignment is Wednesday, Sept 30, 2015 (9:00 am).
• Assignment solution must be well referenced. References must be listed in text and at the end of the assignment.
• Hard-copy and e-mail submissions are not acceptable and will not be marked.
Note #1: Students who do not submit by the due date will have their mark reduced. The faculty rule states:
Work submitted late without documented approval of the Unit Chair will be penalized. Assignments that are submitted after the submission date will be subject to a mark penalty equal to 10% of the marks per day of the marks available for the piece of work, up to and including three days after the published due date. Assignments submitted more than three days after the published submission date will not be marked.
Note #2: All workings must be shown for all mathematic/numerical problems.

ASSIGNMENT TASKS

Task 1
(4 marks) Both the CSMA/CD with Token bus medium access control methods can be used in real time systems. Which one is better suited for real time applications? Explain.

Task 2
(6 marks) Suppose you want to build a home network that includes a router with an ADSL connection to the Internet, a wireless IEEE802 Wireless LAN, and three wireless IEEE802 Wireless LAN adaptors. Find specific products to suit your needs and price them out.

Task 3
(4 marks) Briefly describe attacks against security and discuss three desirable properties of secure communication.

Task 4
(5 marks) Suppose that N people wish to communicate with each other using a shared medium, i.e., all transmissions can be read by all participants. Communication between any two participants must be kept confidential. How many keys would be required to achieve this using symmetric cryptosystems? How many key pairs would be required using public key cryptosystems?

Task 5
(6 marks) Provide a definition of the mono-alphabetic cipher. Describing encoding the message “Security is important” using a mono-alphabetic cipher of your choosing. What is involved in such a brute force attack?

Task 6
(5 marks) Consider our authentication protocol 4.0, in which Alice authenticates herself to Bob, which we saw works well (i.e., we found no flaws in it.). Now suppose that at the same time that Alice authenticates herself to Bob, Bob must authenticate himself to Alice. Give a scenario by which Trudy, pretending to be Alice, can now authenticate herself to Bob as Alice. (Hint: consider that the sequence of operations of ap4.0, one with Trudy initiating and one with Bob initiating, can be arbitrarily interleaved. Pay particular attention to the fact that both Bob and Alice will use a nonce, and that if care is not taken, the same nonce can be used, maliciously).

Solution: #8929

SIT202 Computer Networks Assignment 3 Complete Solution

A protocol is the set of rules that are must be followed for transmission. The transmission method used by Ethernet is CSMA/CD (Carrier sense multiple access with collision...