Wireshark Lab: HTTP
SOLUTION
Supplement to Computer Networking: A Top-Down
Approach, 6th ed., J.F. Kurose and K.W. Ross
The following screen shots showing the HTTP GET and HTTP reply answer these questions:
1. Is your browser running HTTP version 1.0 or 1.1? What version of HTTP is the server
running?
2. What languages (if any) does your browser indicate that it can accept to the server?
3. What is the IP address of your computer? Of the gaia.cs.umass.edu server?
2. The HTTP CONDITIONAL GET/response interaction
Here’s a screenshot after doing the two identical HTTP GETs:
Answer the following questions:
8. Inspect the contents of the first HTTP GET request from your browser to the server.
Do you see an “IF-MODIFIED-SINCE” line in the HTTP GET?
9. Inspect the contents of the server response. Did the server explicitly return the
contents of the file? How can you tell?
10. Now inspect the contents of the second HTTP GET request from your browser to the
server. Do you see an “IF-MODIFIED-SINCE:” line in the HTTP GET? If so, what
information follows the “IF-MODIFIED-SINCE:” header?
3. Retrieving Long Documents
In our answer below, we use the http-ethereal-trace-3 packet trace file. The HTTP GET
12. How many HTTP GET request messages did your browser send? Answer: 1. Which
packet number in the trace contains the GET message for the Bill or Rights? Answer: 8.
13. Which packet number in the trace contains the status code and phrase associated with the
response to the HTTP GET request? Answer: packet 10.
14. What is the status code and Phrase in the response? Answer: 200 (OK)
15. How many data-containing TCP segments were needed to carry the single HTTP
response and the text of the Bill of Rights? Answer: three packets (10, 11, 13 in the trace)
4. HTML Documents with Embedded Objects
16. How many HTTP GET request messages did your browser send? Answer: there were
17. Can you tell whether your browser downloaded the two images serially, or whether they
5 HTTP Authentication
Finally, let’s try visiting a web site that is password-protected and examine the sequence
of HTTP message exchanged for such a site. The URL
http://gaia.cs.umass.edu/wireshark-labs/protected_pages/HTTP-wireshark-file5.html is
password protected. The username is “wireshark-students” (without the quotes), and the
password is “network” (again, without the quotes). So let’s access this “secure”
password-protected site. Do the following:
Type the requested user name and password into the pop up box.
• Stop Wireshark packet capture, and enter “http” in the display-filter-specification
window, so that only captured HTTP messages will be displayed later in the
packet-listing window.
Answer the following questions:
18. What is the server’s response (status code and phrase) in response to the initial HTTP
GET message from your browser? Answer: Packet 6 in the trace contains the first GET
19. When your browser’s sends the HTTP GET message for the second time, what new field
is included in the HTTP GET message? Answer: The HTTP GET includes the