计算机网络实验报告一

计算机网络实验报告一

班级：智能

1401

姓名：蒙寿伟

学号：

2

一、

HTTP

1.

The Basic HTTP GET/response interaction

实验步骤：

up your web browser.

2. Start up the Ethereal packet sniffer, as described in the Introductory lab (but don’t

yet begin packet capture). Ente

r “http” (just the letters, not the quotation marks)

in the display-filter-specification window, so that only captured HTTP messages

will be displayed later in the packet-

listing window. (We’re only interested in the

HTTP protocol here, and don’t want to s

ee the clutter of all captured packets).

3. Wait a bit more than one minute (we’ll see why shortly), and then begin Ethereal

packet capture.

4. Enter the following to your browser

/ethereal-labs/

Your browser should display the very simple, one-line HTML file.

5. Stop Ethereal packet capture.

实验结果：

1.

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

server running?

结果：我的浏览器

HTTP

的版本是

1.1

，服务器的

HTTP

版本是

1.1

2.

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

server?

结果：

浏览器可以接受的语言版本：

zh- Hans-CN,zh-Hans;q=0.8,en-US;q=0.5,en;q=0.3

3.

What is the IP address of your computer? Of the server?

结果：电脑的

IP

地址为

192.168.1.8

服务器

IP

为

: 128.119.245.12

1

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

结果：状态代码是

200

< br>（请求成功）

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

结果：

Last-Modified: Tue, 18 Apr 2017 05:59:01 GMTrn

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

结果：返回到浏览器的内容的字节

126

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

通过检查数据包内 容窗口中的原始数据，

您会看到任何标题在数据包列表窗

口中未 显示的数据中？

如果是这样，找出一个。

结果：没有。

2.

The HTTP CONDITIONAL GET/response interaction

实验步骤：

?

Start up your web browser, and make sure your browser’s cache is cleared, as

2

discussed above.

?

Start up the Ethereal packet sniffer

?

Enter the following URL into your browser

/ethereal-labs/

Your browser should display a very simple five-line HTML file.

?

Quickly enter the same URL into your browser again (or simply select the refresh

button on your browser)

?

Stop Ethereal packet captur

e, 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-2 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：

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?

结果：第一次

HTTP GET

没有看到“

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?

检查服务器响应的内容。

服务器是否显式返回文件的内容？

你怎么知道？

结果：返回内容：

3

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?

客户端第二次请求此

URL

时，

根据

HTTP

协议的规定，

浏览器会向服务器传送

If-Modified-Since

报头

结果：有“

IF-MODIFIED- SINCE:

”

，内容是：

If- Modified-Since: Sat, 22 Apr 2017

05:59:01 GMTrn

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.

答案：状态码和相应状态信息的值为

302 Moved Te mporarily

。代表的意思是新

的

URL

应该被视为临时性的替代。

3.

Retrieving Long Documents

4

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

/ethereal-labs/

Your browser should display the rather lengthy US Bill of Rights.

?

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-3 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：

12.

How many HTTP GET request messages were sent by your browser?

结果：

2

个

GET

请求

13. How many data-containing TCP segments were needed to carry the single HTTP

response?

需要多少数据包含

TCP< /p>

片段来承载单个

HTTP

响应？

结果：

4

个

14. What is the status code and phrase associated with the response to the HTTP GET

request?

答案：状态码和短语是

200 OK

：表示请求成功，信息包含在响应的报文中。

5

15.

Are

there

any

HTTP

status

lines

in

the

transmitted

data

associated

with

a

TCPinduce

d “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

/ethereal-labs/

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 web site.

The image of our book’s cover is

stored at the 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：

6

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

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< /p>

,

并没有等第

?

个图片请求得到回复后

才继续第二次请求。

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

7

/ethereal-labs/protected_pages/

Type the requested user name and password into the pop up box..

?

Stop Ethereal p

acket 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 t

he 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 MTEyMzoyMzEzrn

Credentials: 1123: 2313

（

用户名及密码

）

第一次请求：

第二次请求：

8