Use the ping command to send ICMP packets to the target host and capture both the request and response packets.
(2) Analyze ICMP request packet ——- Echo (ping) request packet, analyze 53
(3) Analyze ICMP response packet ——— Echo (ping) reply, corresponding to frame 54
(4) Capture ICMP packets —— Request timed out packets
From the above, it can be seen that the info in the packet indicates, Time-to-live shows this frame is a request timed out packet
(5) Analyze request timed out packet, analyzing frame 6201
Speaking of ICMP request message timeout, it is necessary to first discuss the data field format of the ICMP error report message. As shown in the figure below
The format of the ICMP error message is: extract the header and the first 8 bytes of the data field of the received IP packet (which is the format of the ICMP message). Use it as the data field of the ICMP message. Adding the first 8 bytes of the ICMP error message constitutes an ICMP error report message.
(5) Capture ICMP Destination Unreachable packets
(6) Analyze ICMP Destination Unreachable packets, analyzing 6514, which is the info showing: Destination Unreachable
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