Ask Question, Ask an Expert

+61-413 786 465

info@mywordsolution.com

Ask Computer Network & Security Expert

Assignment

1. Consider a TCP connection between Host A and Host B. Suppose that the TCP segments traveling from Host A to Host B have source port number 12048 and destination port number 80. What are the source and destination port numbers for segments traveling from Host B to Host A?

2. Suppose a process in Host C has a UDP socket with port number 6789, Suppose both Host A and Host B each send a UDP segment to Host C with destination port number 6789. Will both of these segments be directed to the same socket at Host C? If so, how will the process at Host C know that these two segments originated from two different hosts?

3. Suppose that a Web server runs in Host C on port 80. Suppose this Web server uses persistent connections, and is currently receiving requests from two different Hosts, A and B. Are all of the requests being sent through the same socket at Host C? If they are being passing through different sockets, do both of the sockets have port 80? Discuss and explain.

4. True or false? Please explain your answers.

a. Host A is sending Host B a large file over a TCP connection. Assume Host B has no data to send Host A. Host B will not send acknowledgements to Host A because Host B cannot piggyback the acknowledgements on data.

b. The size of the TCP RcvWindow never changes throughout the duration of the connection.

c. Suppose Host A is sending Host B a large file over a TCP connection. The number of unacknowledged bytes that A sends to B cannot exceed the size of the receive buffer in Host B.

d. Suppose Host A is sending a large file to Host B over a TCP connection. If the sequence number for a segment of this connection is m, then the sequence number for the subsequent segment must be m+1.

e. The TCP segment has a field in its header for RcvWindow.

5. Suppose Host A sends two TCP segments back to back to Host B over a TCP connection. The first segment has sequence number 526; the second has sequence number 1526.

a. How much data is in the first segment?

b. Suppose that the first segment is lost but the second segment arrives at B. In the acknowledgement that Host B sends back to Host A, what will be the acknowledgement number?

6. UDP and TCP use 1s complement for their checksums. Suppose you have the following three 8-bit bytes: 01011111, 01110000, 11001001. What is the 1s complement of the sum of these 8-bit bytes? (Note that although UDP and TCP use 16-bit words in computing the checksum, for this problem you are being asked to consider 8-bit sums.) Show all work. Why is it that UDP takes the 1s complement of the sum; that is. Why not just use the sum? With the 1s complement schema, how does the receiver detect errors? Is it possible that a 1-bit error will go undetected? How about 2-bit error?

7. Consider the following plot of TCP window size as a function of time. Assume TCP Reno is the protocol experiencing the behavior shown above, answer the following questions. In all cases, you should provide a short discussion justifying your answer.

2176_TCP-Congestion.jpg

a. Is TCP Congestion avoidance operating in interval [6, 16]? Why or why not?
b. Is TCP congestion avoidance operating in interval [23, 26]? Why or why not?
c. After the 16th transmission round, is segment loss detected by a triple duplicate ACK or by a timeout? Why?
d. After the 22nd transmission round, is segment loss detected by a triple duplicate ACK or by a timeout? Why?
e. What is the value of Threshold at the 25th transmission round?
f. What is the value of Threshold at the 6th transmission round?

8. Socket Programming Assignment: Web Server (page 179)

In this lab, you will learn the basics of socket programming for TCP connections in Python: how to create a socket, bind it to a specific address and port, as well as send and receive a HTTP packet. You will also learn some basics of HTTP header format.

You will develop a web server that handles one HTTP request at a time. Your web server should accept and parse the HTTP request, get the requested file from the server's file system, create an HTTP response message consisting of the requested file preceded by header lines, and then send the response directly to the client. If the requested file is not present in the server, the server should send an HTTP "404 Not Found" message back to the client.

Code

Below you will find the skeleton code for the Web server. You are to complete the skeleton code. The places where you need to fill in code are marked with #Fill in start and #Fill in end. Each place may require one or more lines of code.

Running the Server

Put an HTML file (e.g., HelloWorld.html) in the same directory that the server is in. Run the server program. Determine the IP address of the host that is running the server (e.g., 128.238.251.26). From another host or the same host if you run the server on the local manchine, open a browser and provide the corresponding URL.

‘HelloWorld.html' is the name of the file you placed in the server directory. Note also the use of the port number after the colon. You need to replace this port number with whatever port you have used in the server code. In the above example, we have used the port number 6789. The browser should then display the contents of HelloWorld.html. If you omit ":6789", the browser will assume port 80 and you will get the web page from the server only if your server is listening at port 80.

You can also run the server program on your own PC and access the webserver from the same PC using the IP address for local host (127.0.0.1).

Then try to get a file that is not present at the server. You should get a "404 Not Found" message.

What to Hand in

You will hand in the complete server code along with the screen shots of your client browser, verifying that you actually receive the contents of the HTML file from the server.

Skeleton Python Code for the Web Server (Use the code on the next page as the skeleton of your .py file and insert lines of code needed between #Fill in state and #Fill in end. Please note that Python programs get structured through indentation, copy and paste may change the indentation of the following lines. You are suggested to use Python 3.x.

#import socket module

import socket
import sys

serversocket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
print("Socket Created!!")

try:
#bind the socket
#fill in start
#fill in end
except socket.error as msg:
print("Bind failed. Error Code: " + str(msg[0]) + "Message: " + msg[1])
sys.exit()
print("Socket bind complete")

#start listening on the socket
#fill in start
#fill in end
print('Socket now listening')

while True:
#Establish the connection
connectionSocket, addr = #fill in start #fill in end
print('source address:' + str(addr))
try:
#Receive message from the socket
message = #fill in start #fill in end
print('message = ' + str(message))
#obtian the file name carried by the HTTP request message
filename = message.split()[1]
print('filename = ' + str(filename))
f = open(filename[1:], 'rb')
outputdata = f.read()
#Send the HTTP response header line to the socket
#fill in start
#fill in end
#Send the content of the requested file to the client
connectionSocket.send(outputdata)
#close the connectionSocket
#fill in start
#fill in end

print("Connection closed!")
except IOError:
#Send response message for file not found
#fill in start
#fill in end

#Close the client socket
#fill in start
#fill in end
serverSocket.close().

Computer Network & Security, Computer Science

  • Category:- Computer Network & Security
  • Reference No.:- M92743882

Have any Question?


Related Questions in Computer Network & Security

Overviewthis assignment has three major aims- to help

Overview This assignment has three major aims: - To help students gain good understanding of theoretical and practical material. - To encourage students to use content analysis summaries to prepare for tests, examination ...

Question 12326 packet tracer - configuring pap and chap

Question 1 2.3.2.6 Packet Tracer - Configuring PAP and CHAP Authentication Submit your answer as Q1.pka Question 2 2.5.1.2 Packet Tracer - Skills Integration Challenge Submit your answer as Q2.pka Question 3 3.4.2.4 Pack ...

Recent tariff actions by president trump include raising

Recent tariff actions by President Trump include raising tariffs and quotas on imports of both manufactured goods like televisions and automobiles and intermediate goods like steel and aluminum sheets. How will the econo ...

Question a small company is assigned the class c network

Question : A small company is assigned the class C network 205.67.35.0. You need to divide this network to provide subnets for three departments using fixed-length subnetting. The departments are approximately the same s ...

Advanced network design assessment - human factors in

Advanced Network Design Assessment - Human factors in network analysis and design Purpose of the assessment - This assignment is designed to assess students' knowledge and skills related to the following learning outcome ...

Part auniversity of neverland offers more than 300

Part A University of Neverland offers more than 300 undergraduate programs. The Bachelor of Dreams is one of the highly regarded program offered by the University. The University tries to improve all its programs by intr ...

Compare the importance of three categories described in the

Compare the importance of three categories described in the article: 1. window of exposure, 2. full public disclosure, 3. reasonable disclosure for three types of software applications: 4. military, 5. medical, 6. educat ...

What are three ways that even every forecast model should

What are three ways that even every forecast model should be evaluated to obtain the best forecast result.

Buffer overflowthe common vulnerabilities and exposures cve

Buffer overflow The "Common Vulnerabilities and Exposures" (CVE) is a list of cybersecurity vulnerabilities that have been discovered, and they are collected in a database for everyone to see and improve or patch their s ...

Data communications and networks assignment -aim a library

Data Communications and Networks Assignment - Aim: A library research and industry related project is to be carried out on a topic of your choice. The project topic must be related to Data Communications and Networking. ...

  • 4,153,160 Questions Asked
  • 13,132 Experts
  • 2,558,936 Questions Answered

Ask Experts for help!!

Looking for Assignment Help?

Start excelling in your Courses, Get help with Assignment

Write us your full requirement for evaluation and you will receive response within 20 minutes turnaround time.

Ask Now Help with Problems, Get a Best Answer

Why might a bank avoid the use of interest rate swaps even

Why might a bank avoid the use of interest rate swaps, even when the institution is exposed to significant interest rate

Describe the difference between zero coupon bonds and

Describe the difference between zero coupon bonds and coupon bonds. Under what conditions will a coupon bond sell at a p

Compute the present value of an annuity of 880 per year

Compute the present value of an annuity of $ 880 per year for 16 years, given a discount rate of 6 percent per annum. As

Compute the present value of an 1150 payment made in ten

Compute the present value of an $1,150 payment made in ten years when the discount rate is 12 percent. (Do not round int

Compute the present value of an annuity of 699 per year

Compute the present value of an annuity of $ 699 per year for 19 years, given a discount rate of 6 percent per annum. As