15. Are there any HTTP status lines in the transmitted data associated with a TCPinduced “Continuation”?
结果：有，对于一个大的HTML文件会被TCP分为若干个独立的包。
4. HTML Documents with Embedded Objects
实验步骤：
? Start up your web browser, and make sure your browser’s cache is cleared, as discussed above.
? Start up the Ethereal packet sniffer ? Enter the following URL into your browser
http://gaia.cs.umass.edu/ethereal-labs/HTTP-ethereal-file4.html
Your browser should display a short HTML file with two images. These two images are referenced in the base HTML file. That is, the images themselves are not contained in the HTML; instead the URLs for the images are contained in the downloaded HTML file. As discussed in the textbook, your browser will have to retrieve these logos from the indicated web sites. Our publisher’s logo is retrieved from the www.awl.com web site. The image of our book’s cover is stored at the manic.cs.umass.edu server.
? Stop Ethereal packet capture, and enter “http” in the display-filter-specification window, so that only captured HTTP messages will be displayed.
? (Note: If you are unable to run Ethereal on a live network connection, you can use the http-ethereal-trace-4 packet trace to answer the questions below; see footnote 1. This trace file was gathered while performing the steps above on one of the author’s computers.) 实验结果：
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16. How many HTTP GET request messages were sent by your browser? To which Internet addresses were these GET requests sent? 结果：
浏览器一共发出了4个HTTP GET请求，目的IP如图所示
17. Can you tell whether your browser downloaded the two images serially, or whether they were downloaded from the two web sites in parallel? Explain. 浏览器在下载这两个图片时，是串行下载还是并行下载？请解释 结果：
是并?下载。因为两个图?片是连续请求,并没有等第?个图片请求得到回复后才继续第二次请求。
5.HTTP Authentication
实验步骤：
? Make sure your browser’s cache is cleared, as discussed above, and close down your browser. Then, start up your browser ? Start up the Ethereal packet sniffer ? Enter the following URL into your browser
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http://gaia.cs.umass.edu/ethereal-labs/protected_pages/HTTP-ethereal-file5.html Type the requested user name and password into the pop up box..
? Stop Ethereal packet capture, and enter “http” in the display-filter-specification window, so that only captured HTTP messages will be displayed later in the packet-listing window.
? (Note: If you are unable to run Ethereal on a live network connection, you can use the http-ethereal-trace-5 packet trace to answer the questions below; see footnote 1. This trace file was gathered while performing the steps above on one of the author’s computers.) 实验结果：
18. What is the server’s response (status code and phrase) in response to the initial HTTP GET message from your browser?
对于浏览器发出的最初的HTTP GET请求，服务器的响应是什么？ 结果：401 Unauthorized(未经授权)
19. When your browser’s sends the HTTP GET message for the second time, what new field is included in the HTTP GET message? 当浏览器发出第二个HTTP GET请求时，在HTTP GET报文中包含了哪些新的字段？ 结果：出现新字段：Authorization: Basic MTEyMzoyMzEz\\r\\n Credentials: 1123:2313（用户名及密码） 第一次请求：
第二次请求：
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二、TCP
实验步骤：
1. Capturing a bulk TCP transfer from your computer to a remote Server
2. A first look at the captured trace
3. TCP Basics
实验结果：
1. What is the IP address and TCP port number used by your client computer (source) to transfer the file to gaia.cs.umass.edu? What is the IP address and port
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number used by gaia.cs.umass.edu to receive the file.
答：client computer: IP address: 10.63.236.170 TCP port number: 60813 Gaia.cs.umass.edu: IP address: 128.119.245.12 TCP port number: 80
2. 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? 答：
第一次握手：
Sequence number: 0 (relative sequence number), SYN被置位，SYN=1
第二次握手：Sequence number: 0，Acknowledgment number: 1，SYN=1
第三次握手：
Sequence number: 1，Acknowledgment number: 1，SYN=0
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