LAB2_Ethereal_Ethernet_ARP

LAB2_Ethereal_Ethernet_ARP - Ethereal Lab: Ethernet and ARP...

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Ethereal Lab: Ethernet and ARP Version: 1.0 © 2005 J.F. Kurose, K.W. Ross. All Rights Reserved Computer Networking: A Top- down Approach Featuring the Internet, 3 rd edition. In this lab, we’ll investigate the Ethernet protocol and the ARP protocol. Before beginning this lab, you’ll probably want to review sections 5.5 (Ethernet), 5.4.1 (link- layer addressing) and 5.4.2 (ARP) in the text. RFC 826 ( ftp://ftp.rfc-editor.org/in- notes/std/std37.txt ) contains the gory details of the ARP protocol, which is used by an IP device to determine the IP address of a remote interface whose Ethernet address is known. 1. Capturing and analyzing Ethernet frames Let’s begin by capturing a set of Ethernet frames to study. Do the following 1 : First, make sure your browser’s cache is empty. (To do this under Netscape 7.0, select Edit->Preferences->Advanced->Cache and clear the memory and disk cache. For Internet Explorer, select Tools->Internet Options->Delete Files Start up the Ethereal packet sniffer Enter the following URL into your browser http://gaia.cs.umass.edu/ethereal-labs/HTTP-ethereal-file3.html Your browser should display the rather lengthy US Bill of Rights. Stop Ethereal packet capture. First, find the packet numbers (the leftmost column in the upper Ethereal window) of the HTTP GET message that was sent from your computer to gaia.cs.umass.edu, as well as the beginning of the HTTP response message sent to your computer by gaia.cs.umass.edu. You should see a screen that looks something like this (where packet 10 in the screen shot below contains the HTTP GET message) 1 If you are unable to run Ethereal live on a computer, you can download the zip file http://gaia.cs.umass.edu/ethereal-labs/ethereal-traces.zip and extract the file ethernet--ethereal-trace-1 . The traces in this zip file were collected by Ethereal running on one of the author’s computers, while performing the steps indicated in the Ethereal lab. Once you have downloaded the trace, you can load it into Ethereal and view the trace using the File pull down menu, choosing Open , and then selecting the ethernet-ethereal-trace-1 trace file. You can then use this trace file to answer the questions below.
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Since this lab is about Ethernet and ARP, we’re not interested in IP or higher- layer protocols. So let’s change Ethereal’s “listing of captured packets” window so that it shows information only about protocols below IP. To have Ethereal do this, select Analyze->Enabled Protocols. Then uncheck the IP box and select OK . You should now see an Ethereal window that looks like:
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This note was uploaded on 12/29/2009 for the course EE 450 at USC.

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LAB2_Ethereal_Ethernet_ARP - Ethereal Lab: Ethernet and ARP...

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