Chapter 1 : Lab 1.2.2 Capturing and Analyzing Network TrafficTelah dituliskan: Desember 31, 2010
Step 1: Connect the routers and configure
a. Connect the two routers with a serial cable. RouterA will provide the clocking signal between the two routers. Use S0/0/0 on both routers to connect them.
b. Use RIP as the protocol when configuring both routers. Advertise the appropriate networks on each router.
c. Connect the Fa0/0 on RouterA with a crossover cable to the server running the Discovery Server Live CD.
d. RouterB will use a straight-through cable from its Fa0/0 to connect to the switch through the Fa0/1. Configure the routers as shown in the topology diagram above.
Step 2: Connect the host to the switch and configure
Step 3: Verify connectivity using ping
a. To verify that the network is set up successfully, ping from the host to the server.
b. If the ping is not successful, verify the connections and configurations again. Check to ensure that all cables are correct and that connections are seated. Check the host, server, and router configurations.
c. Was the ping successful? ( yes, it was)
Step 4: Launch Wireshark
NOTE: Wireshark may be downloaded from the Internet at http://www.wireshark.org and installed on each local host. If this is not possible, Wireshark may be run from the Discovery Live CD. Check with your instructor to determine which procedure to follow.
a. If running Wireshark from the local host, double-click on the icon to begin the application and proceed to step d. If running Wireshark from the Discovery server, proceed to step b.
b. From the K Start menu on the server desktop, choose Internet> Wireshark Network Analyzer.
c. Launch Wireshark if it is not already open. If prompted for a password, enter discoverit.
d. To start data capture, go to the Capture menu click Options. The Options dialog provides a range of settings and filters that determine how much data traffic is captured.
e. Ensure that Wireshark is set to monitor the correct interface. From the Interface drop-down list, select the network adapter in use. For most computers, this will be the connected Ethernet Adapter.
f. Next, other options can be set. The two options highlighted below are worth examination: Capture packets in promiscuous mode and Enable transport name resolution.
• Setting Wireshark to capture packets in promiscuous mode
• Setting Wireshark for network name resolution
• Clicking the Start button starts the data capture process. A message box displays the progress of this process.
• Create some traffic to be captured. Issue a ping and tracert from the host and watch for routing updates.
• Clicking the Stop button terminates the capture process. The main screen is displayed.
• The PDU (or Packet) List pane at the top of the diagram displays a summary of each packet captured. By clicking on packets in this pane, you control what is displayed in the other two panes.
• The PDU (or Packet) Details pane in the middle of the diagram displays the packet selected in the Packet List Pane in more detail.
• The PDU (or Packet) Bytes pane at the bottom of the diagram displays the actual data (in hexadecimal form representing the actual binary) from the packet selected in the Packet List pane, and highlights the field selected in the Packet Details pane.
Step 5: Ping PDU Capture
a. Launch Wireshark.
b. Set the Capture Options as described in Step 4 and start the capture process.
c. From the command line of the host, ping the IP address of the server on the other end of the lab topology. In this case, ping the Discovery Server Live CD using the command ping 172.17.1.1.
d. After receiving the successful replies to the ping in the command-line window, stop the packet capture.
Step 6: Examine the Packet List pane
a. The Packet List pane on Wireshark should now look similar to this:
b. Look at the packets listed; we are interested in the packets numbered 3 through 10.
c. Locate the equivalent packets on the packet list on your computer. The numbers may be different.
d. From the Wireshark Packet List, answer the following questions:
1) What protocol is used by ping? (protocol yang digunakan adalah TCP)
2) What is the full protocol name? (Inthernet Protocol, Src : 192.168.174.14 (192.168.174.14) Dst : ( 192.168.172.1))
3) What are the names of the two ping messages? (Replay and Request)
4) Are the listed source and destination IP addresses what you expected?
Step 7: Examine the Packet Details pane
a. Select (highlight) the first echo request packet on the list with the mouse. The Packet Detail pane will now display something similar to this:
b. Click each of the four + to expand the information. The packet Detail Pane will now be similar to:
c. Spend some time scrolling through this information. At this stage of the course, you may not fully understand the information displayed. Make a note of the information you do recognize.
d. Locate the two different types of Source and Destination.
e. Select a line in the Packets Detail pane (middle pane). Notice that all or part of the information in the Packet Bytes pane also becomes highlighted.
f. Go to the File menu and click Close.
g. Click Continue without Saving when this message box appears.
Step 8: Perform an FTP PDU Capture
a. Assuming that Wireshark is still running from the previous steps, start packet capture by clicking the Start option on the Wireshark Capture menu.
b. At the command line on your host, enter ftp 172.17.1.1. When the connection is established, enter anonymous as the user.
c. When successfully logged in, enter get /pub/Discovery_1/document_1 and press the Enter key. Note that there is a space after get. This command will start downloading the file from the ftp server. The output will look similar to:
C:\> ftp 172.17.1.1
Connected to 172.17.1.1
220 Welcome to The CCNA-Discovery FTP service.
ftp> get /pub/Discovery_1/document_1
200 PORT command successful. Consider using PASV.
150 Opening BINARY mode data connection for pub/Discovery_1/document_1
226 File send OK.
ftp: 73 bytes received in 0.03Seconds 2.35Kbytes/sec.
d. When the file download is complete, enter quit.
e. Stop the PDU capture in Wireshark.
Step9: Examine the Packet List pane
a. Increase the size of the Wireshark Packet List pane and scroll through the PDUs listed.
b. Locate and note those PDUs associated with the file download. These will be the PDUs from the Layer 4 protocol TCP and the Layer 7 protocol FTP.
c. Identify the three groups of PDUs associated with the file transfer. The first group is associated with the connection phase and logging into the server. List examples of messages exchanged in this phase.
d. Locate and list examples of messages exchanged in the second phase that is the actual download request and the data transfer.
e. The third group of PDUs relate to logging out and breaking the connection. List examples of messages exchanged during this process.
f. Locate recurring TCP exchanges throughout the FTP process. What feature of TCP does this indicate?
Step 10: Examine Packet Details and Packet Byte panes
a. Select (highlight) a packet on the list associated with the first phase of the FTP process. View the packet details in the Packet Details pane.
b. What are the protocols encapsulated in the frame?
c. Highlight the packets containing the username and password. Examine the highlighted portion in the Packet Byte pane. What does this say about the security of this FTP login process? As you can see, the details for each section and protocol can be expanded further. Why are there two types? Jawab: Karena masing masing memiliki fungsi tertentu, misalnya meskipun sama sama menampilkan alamat IP address akan tetapi yang pertama berfungsi sebagai koneksi dengan alamat tujuan beserta protocol yang digunakan, sedangkan yang kedua berfungsi sebagai penerjemah dari koneksi ping alamat yang dituju.
d. What protocols are in the Ethernet frame? Jawab: HTTP
Step 11: Perform an HTTP PDU Capture
a. Start packet capture. Assuming that Wireshark is still running from the previous steps, start packet
capture by clicking the Start option on the Wireshark Capture menu.
b. Launch a web browser on the computer that is running Wireshark.
c. Enter the IP address of the Discovery Server 172.17.1.1 in the address box. When the webpage has
fully downloaded, stop the Wireshark packet capture.
Step 12: Examine the Packet List pane
a. Increase the size of the Wireshark Packet List pane and scroll through the PDUs listed.
b. Locate and identify the TCP and HTTP packets associated with the webpage download.
c. Note the similarity between this message exchange and the FTP exchange.
Step 13: Examine the Packet Details and Bytes panes
a. In the Packet List pane, highlight an HTTP packet that has the notation (text/html) in the Info
b. In the Packet Details pane, click the + next to Line-based text data: html. When this information expands, what is displayed?
c. Examine the highlighted portion of the Byte pane. This portion shows the HTML data carried by the packet.
d. When finished, close the Wireshark file and continue without saving.
Step 14: Analyze the capture
a. Look at the capture below and examine the various protocols being used in this network.
b. List the protocols used on the network shown above.
c. Examine the capture below.
d. What two protocols are listed in this capture that was not listed in the previous capture?
e. Compare the first capture in Step 14 with the second capture. What is one noticeable difference
between the HTTP and HTTPS protocols?
Step 15: Reflection
How are the OSI and TCP/IP Layer models reflected in the captured network data provided by Wireshark?
( Pada wireshark proses pengiriman paket data dibagi menjadi 3 bagian, paket pertama menetukan secara umum alamat ip address dalam pengiriman data dan menggunakan protocol apa, pada paket yang kedua jenis nya lebih merinci kepada alamat yang akan digunakan sebagai pengirim dan penerima, dan pada paket ketiga bit data dikalkulasikan sehingga data bisa disimpan dalam bentuk file)