Monday, February 13, 2017

Wireshark Lab #5 - HTML Documents with Embedded Objects

HTML Documents with Embedded Objects
Now that we’ve seen how Wireshark displays the captured packet traffic for large HTML files, we can look at what happens when your browser downloads a file with embedded objects, i.e., a file that includes other objects (in the example below, image files) that are stored on another server(s).

Start up your web browser, and make sure your browser’s cache is cleared, as discussed above.
  • Start up the Wireshark packet sniffer
  • Enter the following URL into your browser
  • Your browser should display a short HTML file with two images. These two images are referenced in the base HTML file. That is, the images themselves are not contained in the HTML; instead the URLs for the images are contained in the downloaded HTML file. Your browser will have to retrieve these images from the indicated web sites.
  • Stop Wireshark packet capture, and enter “http” in the display-filter-specification window, so that only captured HTTP messages will be displayed.
Answer the following questions:
  1. How many HTTP GET request messages did your browser send? 
  2. To which Internet addresses were these GET requests sent?
  3. Can you tell whether your browser downloaded the two images serially, or whether they were downloaded from the two web sites in parallel? Explain.

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