ICMP Lab--This is Homework #6--I announced in class the Homeworks #6 & 7 are due on Dec. 11(Wed), 2002 but I realized that the due date is on the so-called "dead week" in which I should not assign any work to students. So, you do not need to hand them but these homeworks are interesting to carry out.

Open Internet Explorer and find RFC 792(ICMP).

Fill out the following table from the RFC:

Type Message Type

---------------------------------------------------------

0

8

11

Find the Type and Code of the ICMP message for the following case:

“A router needs to fragment but Don’t Fragment bit is set”

Type= ___ Code=____

Open Sniffer and set the filter for IP addresses:

Station 1=your station’s IP address Station 2= your station’s IP address

Select Filter -> select the above one

Capture -> Start

From Command Prompt, enter “ping 127.0.0.1” --This is “loopback address”

Display the captured packets. What kind are they? ____________________

Open Sniffer and set the filter for IP addresses:

Station 1=your station’s IP address Station 2= Any

Select Filter -> select the above one

Capture -> Start

From Command Prompt, enter “ping mit.edu”

Display the captured packets.

Explain the function of 1^st two packets: _________________________________________

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Explain the function of 3^rd & 4^th packets:________________________________________

In the 3^rd & 4^th packets, explain the function of

ICMP: Identifier = xxx----______________________________________________

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ICMP: Sequence number = xxxxx----_____________________________________

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Capture -> Start

From Command Prompt, enter “ping -l 1500 - f mit.edu”

Display the captured packets. Try to ping several other web sites.

Explain what happened? _____________________________________________________

_________________________________________________________________________

Capture -> Start

From Command Prompt, enter “ping -i 1 mit.edu”

Display the captured packets.

Explain what is happening by going over each packet: Explain who sent it and why.

Packet 1: ____________________________________________________

Packet 2: ____________________________________________________

Packet 3: ____________________________________________________

Packet 4: ____________________________________________________

Capture -> Start

From Command Prompt, enter “ping -i 2 mit.edu”

Display the captured packets.

Explain what is happening by going over each packet: Explain who sent it and why.

Packet 1: ___________________________________________________

Packet 2: ___________________________________________________

Packet 3: ___________________________________________________

Packet 4: ___________________________________________________

Capture -> Start

From Command Prompt, enter “tracert mit.edu”

Display the captured packets.

Explain what is happening by going over each packet: Explain who is sending each packet and why. For the reason, look for the IP’s TTL values.

Packet 1: ___________________________________________________

Packet 2: ___________________________________________________

Packet 3: ___________________________________________________

Packet 4: ___________________________________________________

Packet 5: ___________________________________________________

Packet 6: ___________________________________________________

Packet 7: ___________________________________________________

Packet 8: ___________________________________________________

Now compare the result between this(tracert mit.edu) and the above two results(ping -i 1 mit.edu and ping -i 2 mit.edu). What can you conclude from this experiments?

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