【Wireshark Lab v8.0】Lab1：Getting Started
本实验的主要任务是初步熟悉wireshark软件。
以下实验步骤均来自实验指导手册。
实验指导手册下载地址：Jim Kurose Homepage (umass.edu)
Taking Wireshark for a Test Run
- Start up your favorite web browser, which will display your selected homepage.
- Start up the Wireshark software. You will initially see a window similar to that
shown in Figure 2. Wireshark has not yet begun capturing packets.
- To begin packet capture, select the Capture pull down menu and select Interfaces.
This will cause the “Wireshark: Capture Interfaces” window to be displayed (on a
PC) or you can choose Options on a Mac. You should see a list of interfaces, as
shown in Figures 4a (Windows) and 4b (Mac).
此时使用的wifi，所以没有按照实验指导手册推荐以太网接口。
- You’ll see a list of the interfaces on your computer as well as a count of the
packets that have been observed on that interface so far. On a Windows machine,
click on Start for the interface on which you want to begin packet capture (in the
case in Figure 4a, the Gigabit network Connection). On a Windows machine,
select the interface and click Start on the bottom of the window). Packet capture
will now begin - Wireshark is now capturing all packets being sent/received
from/by your computer!
选中wlan后点击start，wireshark便开始抓包
-
Once you begin packet capture, a window similar to that shown in Figure 3 will
appear. This window shows the packets being captured. By selecting Capture
pulldown menu and selecting Stop, or by click on the red Stop square, you can
stop packet capture. But don’t stop packet capture yet. Let’s capture some
interesting packets first. To do so, we’ll need to generate some network traffic.
Let’s do so using a web browser, which will use the HTTP protocol that we will
study in detail in class to download content from a website. -
While Wireshark is running, enter the URL:
http://gaia.cs.umass.edu/wireshark-labs/INTRO-wireshark-file1.html
and have that page displayed in your browser. In order to display this page, your
browser will contact the HTTP server at gaia.cs.umass.edu and exchange HTTP
messages with the server in order to download this page, as discussed in section
2.2 of the text. The Ethernet or WiFi frames containing these HTTP messages (as
well as all other frames passing through your Ethernet or WiFi adapter) will be
captured by Wireshark.
显示内容如下
- After your browser has displayed the INTRO-wireshark-file1.html page (it is a
simple one line of congratulations), stop Wireshark packet capture by selecting
stop in the Wireshark capture window. The main Wireshark window should now
look similar to Figure 3. You now have live packet data that contains all protocol
messages exchanged between your computer and other network entities! The
HTTP message exchanges with the gaia.cs.umass.edu web server should appear
somewhere in the listing of packets captured. But there will be many other types
of packets displayed as well (see, e.g., the many different protocol types shown in
the Protocol column in Figure 3). Even though the only action you took was to
download a web page, there were evidently many other protocols running on your
computer that are unseen by the user. We’ll learn much more about these
protocols as we progress through the text! For now, you should just be aware that
there is often much more going on than “meet’s the eye”!
- Type in “http” (without the quotes, and in lower case – all protocol names are in
lower case in Wireshark) into the display filter specification window at the top of
the main Wireshark window. Then select Apply (to the right of where you entered
“http”) or just hit return. This will cause only HTTP message to be displayed in
the packet-listing window. Figure 5 below shows a screenshot after the http filter
has been applied to the packet capture window shown earlier in Figure 3. Note
also that in the Selected packet details window, we’ve chosen to show detailed
content for the Hypertext Transfer Protocol application message that was found
within the TCP segment, that was inside the IPv4 datagram that was inside the
Ethernet II (WiFi) frame. Focusing on content at a specific message, segment,
datagram and frame level lets us focus on just what we want to look at (in this
case HTTP messages).
-
Find the HTTP GET message that was sent from your computer to the
gaia.cs.umass.edu HTTP server. (Look for an HTTP GET message in the “listing
of captured packets” portion of the Wireshark window (see Figures 3 and 5) that
shows “GET” followed by the gaia.cs.umass.edu URL that you entered. When
you select the HTTP GET message, the Ethernet frame, IP datagram, TCP
segment, and HTTP message header information will be displayed in the packetheader window3. By clicking on ‘+’ and ‘-' and right-pointing and down-pointing arrowheads to the left side of the packet details window, minimize the amount of Frame, Ethernet, Internet Protocol, and Transmission Control Protocol
information displayed. Maximize the amount information displayed about the
HTTP protocol. Your Wireshark display should now look roughly as shown in
Figure 5. (Note, in particular, the minimized amount of protocol information for
all protocols except HTTP, and the maximized amount of protocol information for
HTTP in the packet-header window). -
Exit Wireshark
Congratulations! You’ve now completed the first lab!
What to hand in
-
List 3 different protocols that appear in the protocol column in the unfiltered
packet-listing window in step 7 above. -
How long did it take from when the HTTP GET message was sent until the HTTP
OK reply was received? (By default, the value of the Time column in the packet listing window is the amount of time, in seconds, since Wireshark tracing began. To display the Time field in time-of-day format, select the Wireshark View pull down menu, then select Time Display Format, then select Time-of-day.)
- What is the Internet address of the gaia.cs.umass.edu (also known as www。net.cs.umass.edu)? What is the Internet address of your computer?
- Print the two HTTP messages (GET and OK) referred to in question 2 above. To
do so, select Print from the Wireshark File command menu, and select the
“Selected Packet Only” and “Print as displayed” radial buttons, and then click
OK
