TCP 计算机网络实验报告

陕西师范大学 计算机网络 实验报告 实验五 探索TCP协议 一、实验目的 1.熟悉并掌握 wireshark的操作。 2.通过实验分析并掌握TCP是如何进行数据传输的，及其如何实现拥塞控制、流量控制等 二、实验器材 1.PC机电脑一台。 2．下载wireshark软件并安装 三、实验内容 通过实验分析并掌握TCP是如何进行数据传输的，及其如何实现拥塞控制、流量控制等 四、问题回答 1. Capturing a bulk TCP transfer from your computer to a remote Server Go the http://gaia.cs.umass.edu/wiresharklabs/alice.txt and retrieve an ASCII copy of Alice in Wonderland. Store this file.somewhere on my computer. Next go to http://gaia.cs.umass.edu/wireshark-labs/TCP-wireshark-file1.html.Then I cansee a screen that looks like: start up Wireshark and begin packet capture.Returning to browser, press the “Upload alice.txt file” button to upload the file to the gaia.cs.umass.edu server. Stop Wireshark packet capture. The Wireshark window like this: Then opening the Wireshark captured packet file tcpethereal-trace-1 in http://gaia.cs.umass.edu/wireshark-labs/wireshark-traces.zip , 2. A first look at the captured trace 1. What is the IP address and TCP port number used by the client computer (source) that is transferring the file to gaia.cs.umass.edu? To answer this question, it’s probably easiest to select an HTTP message and explore the details of the TCP packet used to carry this HTTP message, using the “details of the selected packet header window” (refer to Figure 2 in the “Getting Started with Wireshark” Lab if you’re uncertain about the Wireshark windows). ip address Tcp port number 答：client computer (source)： IP address：192.168.1.102 TCP port number：1161 2. What is the IP address of gaia.cs.umass.edu? On what port number is it sending ip address: and receiving TCP segments for this connection? port number 答：the IP address of gaia.cs.umass.edu： IP address：128.119.245.12 port number：80 3. If you have been able to create your own trace, answer the following question:What is the IP address and TCP port number used by your client computer(source) to transfer the file to gaia.cs.umass.edu? ip address: Tcp port number 答：My client computer: IP address:10.2.136.30 Then Wireshark do this, select Analyze->Enabled Protocols. Then uncheck the HTTP box andselect OK. now see an Wireshark window that looks like: 3. TCP Basics Answer the following questions ； 4. What is the sequence number of the TCP SYN segment that is used to initiate the TCP connection between the client computer and gaia.cs.umass.edu? What is it in the segment that identifies the segment as a SYN segment? Syn is 1 Sequence number 答：sequence number:0 ；syn 被设置为1说明是syn段。 5. What is the sequence number of the SYNACK segment sent by gaia.cs.umass.edu to the client computer in reply to the SYN? What is the value of the ACKnowledgement field in the SYNACK segment? How did gaia.cs.umass.edu determine that value? What is it in the segment that identifies the segment as a SYNACK segment? The value of the ACKnowledgement field Sequence number 答：The se