Wireshark HTTP实验—Wireshark Lab: HTTP v7.0(计算机网络自顶向下第七版)

Posted 2022-11-25 之墨_

Wireshark Lab: TCP v7.0

• 1. *The Basic HTTP GET/response interaction*
• 2.*The HTTP CONDITIONAL GET/response interaction*
• *3.Retrieving Long Documents*
• *4.HTML Documents with Embedded Objects*
• *5 HTTP Authentication*

1. The Basic HTTP GET/response interaction

1. Is your browser running HTTP version 1.0 or 1.1? What version of HTTP is the server running?

   

   浏览器与服务器的版本均为$HTTP/1.1$。

2. What languages (if any) does your browser indicate that it can accept to the server?

能接受简体中文以及英文。

3. What is the IP address of your computer? Of the gaia.cs.umass.edu server?
   

   根据$GET$消息的$Destination$可知$gaia.cs.umass.edu$的$IP$地址为$\mathrm{128.119.245.12}$。

   根据$OK$消息的$Source$可知本机$IP$地址为$\mathrm{114.214.246.244}$。

4. What is the status code returned from the server to your browser?
   

   返回$statuscode=200$，正常状态。

5. When was the HTML file that you are retrieving last modified at the server?
   

   上次修改时间为$2022$年$9$月$14$日，星期三，$5$时$59$分$01$秒。

6. How many bytes of content are being returned to your browser?
   

   内容大小为$128bytes$。

7. By inspecting the raw data in the packet content window, do you see any headers within the data that are not displayed in the packet-listing window? If so, name one.

   查看包信息与列表，没有找到未出现的报头。

2.The HTTP CONDITIONAL GET/response interaction

8. Inspect the contents of the first HTTP GET request from your browser to the server. Do you see an “IF-MODIFIED-SINCE” line in the HTTP GET?

   查看$GET$报文，未找到$IF-MODIFIED-SINCE$。

9. Inspect the contents of the server response. Did the server explicitly return the contents of the file? How can you tell?
   

   在本机浏览器缓存已清空的情况下，向服务器发送第一个$GET$请求后，服务器的响应信息包含文件具体内容。
   

   但立即发送第二个$GET$请求，服务器回复的内容中不含$Header$为$Line-basedtextdata$的信息，即服务器并未返回具体的文件内容。因为在第一次访问时浏览器目标网站成功后，浏览器已有了网页内容的缓存，在下一次访问时，当网站内容尚未更新，便会直接从浏览器缓存中获取，因此无需服务器返回具体的文件内容。

10. Now inspect the contents of the second HTTP GET request from your browser to the server. Do you see an “IF-MODIFIED-SINCE:” line in the HTTP GET? If so, what information follows the “IF-MODIFIED-SINCE:” header?
    

在$HypertextTransferProtocol$中找到了$IF-MODIFIED-SINCE$消息，包含的信息为上一次服务器响应信息的更改时间。

11. What is the HTTP status code and phrase returned from the server in response to this second HTTP GET? Did the server explicitly return the contents of the file? Explain.

    $statuscode=304,phrase=NotModified$，表示未发生改变，直接调用缓存中已有的文本。利用缓存可以减轻服务器压力，提高效率。

3.Retrieving Long Documents

12. How many HTTP GET request messages did your browser send? Which packet number in the trace contains the GET message for the Bill or Rights?
    

    浏览器仅发送了一个$HTTPGET$请求消息，序号为$213$。

13. Which packet number in the trace contains the status code and phrase associated with the response to the HTTP GET request?
    

    序号为$238$的响应报文包含了响应$HTTPGET$请求的状态码和短语。

14. What is the status code and phrase in the response?
    

    $ status\\ code=200,phrase=OK$，表示正常响应状态。

15. How many data-containing TCP segments were needed to carry the single HTTP response and the text of the Bill of Rights?

需要4个$TCP$报文段。

4.html Documents with Embedded Objects

16. How many HTTP GET request messages did your browser send? To which Internet addresses were these GET requests sent?
    
    

    发送了$3$个服务器请求，消息中的$FullrequestURI$就是请求的网站。

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.
    

在第一张图片下载请求得到响应后，才发出下载第二张图片的请求，所以图片下载是串行的。

5 HTTP Authentication

18. What is the server’s response (status code and phrase) in response to the initia HTTP GET message from your browser?

$response :\\  status\\ code = 401,phrase=Unauthorized$，表示未经授权，因为此页面需要登录认证。

19. When your browser’s sends the HTTP GET message for the second time, what new field is included in the HTTP GET message.
    

新增了$Authorization$字段，此字段与登录验证的用户名密码相关。