实验六 specificallyWireshark Lab: TCP
一、实验目的
1.通过wireshark抓包理解应用层TCP协议。
二、实验器材
1.PC机电脑一台。
2.Wireshark软件。
三、实验内容
1．依照Wireshark Lab 提供的实验步骤完成实验。
2．回答实验中的问题。
四、实验操作实践与步骤
2. A first look at the captured trace
1. What is the IP address and TCP port number ud by the client computer (source) that is transferring the file to gaia.cs.umass.edu? To answer this question, it’s probably easiest to lect an HTTP message and explore the details of the TCP packet ud to carry this HTTP message, using the “details of the lected packet header window”
2. What is the IP address of gaia.cs.umass.edu? On what port number is it nding and receiving TCP gments for this connection?
If you have been able to create your own trace, answer the following question:
3. What is the IP address and TCP port number ud by your client computer (source) to transfer the file to gaia.cs.umass.edu?
3. TCP Basics
jackfruit4. (1)What is the quence number of the TCP SYN gment that is ud to initiate the TCP connection between the client computer and gaia.cs.umass.edu? (2)What is it in the gment that identifies the gment as a SYN gment?
(1) SYN quence number =0
(2) What is in the red region of the figure above identifies the gment as a SYN gment.
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5. (1)What is the quence number of the SYNACK gment nt by gaia.cs.umass.edu to the client computer in reply to the SYN?(2) What is the value of thetabula rasa ACKnowledgement field in the SYNACK gment? How did gaia.cs.umass.edu determine that value? What is it in the gment that identifies the gment as a SYNACK gment?
the top
(1)SYNACK祛痘食疗 quence number =0, ACKnowledgement=1
combatant(2)ACKnowledgement value= initiate quence number of the
TCP SYN gment+1
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(3)What is in the red region of the figure above identifies the gment as a SYN gment.
6. What is the quence number of the TCP gment containing the HTTP POST comma
nd? Note that in order to find the POST command, you’ll need to dig into the packet content field at the bottom of the Wireshark window, looking for a gment with a “POST” within its DATA field.
The quence number of the TCP gment containing the HTTP POST command is 1.
high fidelity
7. Consider the TCP gment containing the HTTP POST as the first gment in the TCP connection. (1)What are the quence numbers of the first six gments in the TCP connection (including the gment containing the HTTP POST)? (2)At what time was each gment nt? When was the ACK for each gment received?(3) Given the difference between when each TCP gment was nt, and when its acknowledgement was received, what is the RTT value for each of the six 上海意大利留学中介gments?(4) What is the EstimatedRTT value (e page 249 in text) after the receipt of each ACK? (5)Assume that the value of the EstimatedRTT is equal to the measured RTT for the first gment, and then is computed using the EstimatedRTT equation on page 249 for all subquent gments.
