Google Yahoo Cnn - Software Protocols

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CS 433 Assignment 1

September 2, 2016

The software that I decided to install was Wireshark. Installing Wireshark was very easy. I just searched Packet Sniffers windows 10 on google.com and there was a link for Wireshark and I clicked on it. On the main page, I saw an option to download Wireshark on my laptop and I clicked on it and it downloaded Wireshark.exe file. I clicked on the file and installed Wireshark on my laptop. Wireshark is easy to use as when I open it, there is an option to apply search filter on what protocol I would like to see when I visit a website. When I visit any website on my browser Wireshark starts live capturing of the packets that are exchanged between my browser and the website that I go to. There are many features available on Wireshark and I used the live capturing feature to capture all the packets and I saved all the communications for each website I visited so I could review it offline which is one of the other available features in Wireshark. The other feature I used was applying the coloring rule to the packet list so I could use it to better understand the protocols being used. The following is the list of all the websites I used:

Site 1: www.cnn.com

Protocols received: UDP, TCP, QUIC, DNS, and HTTP

Why: UDP stands for User Datagram Protocol. UDP does not provide any error-checking messages meaning if a user does not receive few packets then you will never see them again and we have UDP packets because CNN has live video telecast option and while on it if your internet connection is lost then you lose some part of the telecast which you cannot watch again. TCP stands for Transfer Control Protocol. TCP does provide error-checking messages when the user does not receive a packet they can send an error message that a packet has not been received then it will be re-send to the user. We have TCP because TCP is used when the user selects to go to a web page and browser uses TCP to form the web page on your computer. When you want to sign-in or comment in a website on an article or anything we use TCP. DNS stands for Domain Name System. DNS translates URL of websites into the IP Address for that particular site and sends it to the user using TCP or UDP. So in our case when we visited cnn.com DNS would send us this: 157.166.226.25 with which we can directly access the site as well. We have DNS because we need DNS to translate the web address of CNN.com to its IP Address. HTTP stand Hyper Text Transfer Protocol. HTTP is text based request-response client-server protocol. (Meier, 2011) For example, if a user wants to visit a website then the browser would send HTTP Request to the HTTP server and in turn, the server would send HTTP respond. We need this because we need HTTP to communicate with CNN’s server, in this case, to connect to their site.

Site 2: www.google.com

Protocols received: DNS, HTTP, TCP

Why: I received DNS protocol because it translates the websites URL to its IP Address through which we can access their site. HTTP is needed to connect to the site while TCP protocol is used when the server sends its response to connect then TCP is used to load the page on the client side.

Site 3: www.yahoo.com

Protocols received: DNS, HTTP, TCP, and UDP

Why: We need TCP because while loading if some packets are not received then the client can request the server to re-send the packets. We need UDP because DNS uses UDP to send DNS Query to the server and if it is not received by the DNS server then the DNS Query is sent again using TCP in 3-5 seconds interval from the client side. DNS Query is communicated on Port 53. HTTP is needed to connect to the site using the HTTP Request which is initiated from the client side to the website’s server. In turn websites, server sends HTTP Request and then browser uses TCP to load the page on the client side.