Assignment 3 traeroute, ping Commands

CSP334: Computer Networks
Lab Assignment No 3
Assignment on traeroute, ping Commands

Instructions:
1. This assignment requires you to self-study the manual or associated support material of the traceroute
and ping commands and the related literature. The commands would be introduced to you in the class.
2. For each of your answer paste a screen dump of your screen in support of justification of
your answer, wherever applicable
3. The assingment solution must be written in a Latex file with the required screenshots and the justifying
textual description of your answers. The Latex source files in a ZIP must be uploaded on the moodle
server.
1. Enumerate the steps and briefly discuss how the utility traceroute works using an illustrative website as
the argument to it. In your explanation of the tool operation discuss the answers to following questions
w. r. to traceroute
• What if there was no TTL field in the invocation of the traceroute at all?
• How will the routers in between determine whether the TTL value limit has reached ?
• Should an intermediate router that receives a traceroute packet always respond with an ICMP TTL
exceeded message ? If the answer is a yes, reason why and if the answer is a no, then argue how do
we know the address of all the routers/hops in between us and the destination ?
• Why does traceroute make use of a destination UDP port number which is invalid - i.e. it sends a
packet to a UDP port in the range h33434 to 33534i ?
• How do we know the address of all the routers/hops in between us and the destination when using
the traceroute?
• How is traceroute latency calculated?
2. Execute the traceroute command with www/yahoo.com as argument. Write down the IP address of
yahoo.com that was used for the trace route. Determine the number of iterations required to determine
route. Enlist the IP addresses of all the machines between the source and the destination. What is the
average round trip time of the packet that reached the destination ?
3. With respect to the question no 2, run traceroute on one window of your OS and run tcpdump on the
other window. Analyze the output of tcpdump. Answer the following questionsm giving appropriate
hihglighted snapshots in support of your answer :
a. How many packets are send by traceroute in each iteration ? How can you prove this using the
tcpdump output.
b. Consider one specific iteration of traceroute invocation/iteration. For this specific iteration, what
are the individual round trip times of each of the three probes sent ? What is the average round
trip time ? Does it match with the round trip time returned by traceroute ?
c. In each iteration of traceroute does it use the same port number for the destination ? IF yes, reason
why and if no, then also argue why does it do so.
4. Use the Visual traceroute command at https://www.monitis.com/traceroute/. What is the source addressand the destination address of these packets ?
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5. If you think a firewall stopped the packet, how can one know that a firewall has come in the way ? What
do you think the IP address of that firewall is based on where the trace route stopped?
6. If a firewall stopped has not obstructed the packet sent, what does the last IP address appearing in the
trace route list indicate ?
7. Enlist and briefly explain all the usages of the ping program - explain each use with the help of an
example.
8. Write a small shell script that uses ping to simulate the working of traceroute. Briefly explain the
operation of the script.
9. Explain all the approaches that can be used to do a ping sweep.
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