netstat.txt

SSD8的练习2 希望能帮助大家 参考学习

Answers to the questions in Part 1:

1.(1)
   There is only one TCP connection when the program excutes; 
   The number matches the TCP counter exactly.
   Before the program executes: (copy from the command line window)

TCP Statistics for IPv4

  Active Opens                        = 365
  Passive Opens                       = 16
  Failed Connection Attempts          = 6
  Reset Connections                   = 135
  Current Connections                 = 0
  Segments Received                   = 46444
  Segments Sent                       = 46820
  Segments Retransmitted              = 13

  After the program excutes: (copy from the command line window)

TCP Statistics for IPv4

  Active Opens                        = 366
  Passive Opens                       = 16
  Failed Connection Attempts          = 6
  Reset Connections                   = 135
  Current Connections                 = 1
  Segments Received                   = 46453
  Segments Sent                       = 46829
  Segments Retransmitted              = 13
We can see that the connections increase one when the program is excuting.

(2)
   Before the program excutes,
   Packets Received                   = 115899
   when excuting the program,
   Packets Received                   = 115953
   The packages received are: 115953-115899=54.

   I sent the request "GET /cn/xxgk/index.htm HTTP/1.0" to the server www.whu.edu.cn, the detailed result is:

   You have sent 35 bytes to server.
   You received 8652 bytes from server.

   Since there is only one package to the server,the average size of sent package is:35 bytes;
   And the average size of received package is: 8652/54, 160 bytes approximately.

  I think the reason for the difference of the size between the sent package and the received package is that the content of   the package is different.The send package only contains the request header,but the received package contains both the   header and the entity body. As a result, the received package will be larger than the send package.

2.
  I use my IE to read a Web pages that have 21 embedded pictures in baidu.
  There are one page and 21 pictures currently.
  But during the session, there are tow connections built, as the following:

TCP Statistics for IPv4

  Active Opens                        = 379
  Passive Opens                       = 0
  Failed Connection Attempts          = 8
  Reset Connections                   = 92
  Current Connections                 = 2
  Segments Received                   = 8502
  Segments Sent                       = 6760
  Segments Retransmitted              = 23

  Older versions of HTTP opened a new TCP connection for each file fetched, but HTTP 1.1 tries to maintain the TCP   connection across multiple GET requests. So I think it uses a more recent version of HTTP