And begin wireshark packet capture ping command

Wireshark Lab: ICMP v7.0 Supplement to Computer Networking: A Top-Down Approach, 7th ed., J.F. Kurose and K.W. Ross

“Tell me and I forget. Show me and I remember. Involve me and I understand.” Chinese proverb
© 2005-2016, J.F Kurose and K.W. Ross, All Rights Reserved

1. ICMP and Ping

Let’s begin our ICMP adventure by capturing the packets generated by the Ping program.

The traces in this zip file were collected by Wireshark running on one of the author’s computers, while performing the steps indicated in the Wireshark lab. Once you have downloaded the trace, you can load it into Wireshark and view the trace using the File pull down menu, choosing Open, and then selecting the ICMP-ethereal-trace-1 trace file. You can then use this trace file to answer the questions below.

•Let’s begin this adventure by opening the Windows Command Prompt application (which can be found in your Accessories folder).

Figure 1 Command Prompt window after entering Ping command.

Figure 3 focuses on the same ICMP but has expanded the ICMP protocol information in the packet contents window. Observe that this ICMP packet is of Type 8 and Code 0 - a so-called ICMP “echo request” packet. (See Figure 5.19 of text.) Also note that this ICMP packet contains a checksum, an identifier, and a sequence number.

3 What do we mean by “annotate”? If you hand in a paper copy, please highlight where in the printout you’ve found the answer and add some text (preferably with a colored pen) noting what you found in what you ‘ve highlight. If you hand in an electronic copy, it would be great if you could also highlight and annotate.

1.What is the IP address of your host? What is the IP address of the destination host?

Let’s now continue our ICMP adventure by capturing the packets generated by the Traceroute program. You may recall that the Traceroute program can be used to figure out the path a packet takes from source to destination. Traceroute is discussed in Section 1.4 and in Section 5.6 of the text.

Traceroute is implemented in different ways in Unix/Linux/MacOS and in Windows. In Unix/Linux, the source sends a series of UDP packets to the target destination using an unlikely destination port number; in Windows, the source sends a series of ICMP packets to the target destination. For both operating systems, the program sends the first packet with TTL=1, the second packet with TTL=2, and so on. Recall that a router will
decrement a packet’s TTL value as the packet passes through the router. When a packet arrives at a router with TTL=1, the router sends an ICMP error packet back to the source. In the following, we’ll use the native Windows tracert program. A shareware version of a much nice Windows Traceroute program is pingplotter (www.pingplotter.com). We’ll use pingplotter in our Wireshark IP lab since it provides additional functionality that we’ll need there.

4If you are unable to run Wireshark live on a computer, you can download the zip file
http://gaia.cs.umass.edu/wireshark-labs/wireshark-traces.zip and extract the file ICMP-ethereal-trace-2.

The traces in this zip file were collected by Wireshark running on one of the author’s computers, while performing the steps indicated in the Wireshark lab. Once you have downloaded the trace, you can load it into Wireshark and view the trace using the File pull down menu, choosing Open, and then selecting the ICMP-ethereal-trace-2 trace file. You can then use this trace file to answer the questions below.

Figure 4 Command Prompt window displays the results of the Traceroute program.

Figure 5 displays the Wireshark window for an ICMP packet returned by a router. Note that this ICMP error packet contains many more fields than the Ping ICMP messages.

Answer the following questions:

5.What is the IP address of your host? What is the IP address of the target destination host?

10.Within the tracert measurements, is there a link whose delay is significantly longer than others? Refer to the screenshot in Figure 4, is there a link whose delay is significantly longer than others? On the basis of the router names, can you guess the location of the two routers on the end of this link?

3. Extra Credit