ICMP and Ping

Task 1: Basic Echo Requests

1. Send 4 ICMP Echo Request packets to a public DNS target.
   • ping -c 4 1.1.1.1
   • ping -c 4 8.8.8.8
2. Student Deliverables: Identify the sequence number (icmp_seq), RTT (Round-Trip Time).
3. Q&A:
   1. What does ICMP stand for?
   2. How do you explain the relationship between ICMP and Ping?
   3. Read RFC 792 to take a glance at the ICMP protocol. Read the description about "Echo Request" and "Echo Reply".

Task 2: Packet Loss Rate

1. Send 200 ICMP Echo Request packets to a host inside NCNU (10.20.128.1).
2. Student Deliverables: Count the number of lost packets, and figure out how packet loss rate is calculated. Compare your measurement with your classmates. What is the highest and the lowest value you measured?

Task 3: Sending ICMP Packets by Python

1. Create a virtual environment for this class:
   1. python3 -m venv SNMP
   2. source SNMP/bin/activate
   3. pip install --upgrade pip
2. Install the "icmplib" package:
   • pip install icmplib
3. Run the following program:

   from icmplib import ping
   host = ping('8.8.8.8', privileged=False)
   print(host.avg_rtt)

4. dir(host) shows that ping() also returns several useful attributes:
   • is_alive
   • packets_sent
   • packets_received
   • packet_loss
   • max_rtt
   • min_rtt
5. Compare them with the values you got in running the "ping" Linux command.

Exercise: If I manage several hosts ...

• Imagine that you are managing several hosts, say, 10.20.128.1 ~ 10.20.128.254.
• Please extend the previous program and design how you plan to display the status of each host.
• This week we only need a plain-text output. In the future, we would like to output a webpage.