Question: Examining the Internetwork Layer Time Required: 10 minutes Objective: Capture packets and view the Internetwork layer. Required Tools and Equipment: Net-XX with Wireshark installed Description: In this project, you capture some ICMP packets and examine the IP header information.

1. If necessary, log on to your computer as Net Admin.

2. Start Wireshark and click Capture Options. In the Capture Filter text box, type icmp, and then click Start.

3. Ping your default gateway or DNS server. If you don't remember these IP addresses, use the ipconfig command to display them.

4. In Wireshark, click the Stop the running live capture toolbar icon to stop the capture. Scroll up to the first packet summary line, if necessary.

5. Click a packet summary in the top pane with ICMP in the Protocol field and "Echo (ping) request" in the Info field.

6. Click to expand the line beginning with Internet Protocol. In the header, find the fields discussed previously in "Internet Protocol Version 4." Write the values in the Version, Time to live, Protocol, and Checksum fields.

7. Click to expand the line beginning with Internet Control Message Protocol, and examine the information in the ICMP header. The Type field specifies the type of ICMP message. The data portion of the ICMP field is simply a string of letters. It doesn't matter what's in the data part of the Echo (ping) request message, as long as the reply contains the same data.

8. Exit Wireshark and click Quit without Saving when prompted.

9. Close all open windows, but leave your computer running for the next project.