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Send a Raw ICMP Echo Request (Ping)

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Language

Compiler

2.0s Limit 256MB

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Implementation

Implement a C program that documents raw ICMP echo request construction.

Requirements:

Create a raw socket using socket(AF_INET, SOCK_RAW, IPPROTO_ICMP)
Build an ICMP header with type=8 (echo request) and code=0
Set a 16-bit identifier and a 16-bit sequence number
Include a small payload such as a timestamp or message
Compute the ICMP checksum using the standard algorithm
Print every field of the ICMP header in human-readable form
Show what the raw socket would send and what reply is expected
Explain the difference between IPPROTO_ICMP and IPPROTO_RAW

Success Criteria:

ICMP type and code are clearly printed
Checksum is calculated and displayed
The program explains the echo request / echo reply lifecycle
Output contains the keywords: ICMP, echo, raw socket, checksum

Why This Matters

This is literally what iputils' ping.c does on Linux: open an IPPROTO_ICMP raw socket, fill type/code/id/sequence, and checksum the result before sending. Getting the checksum wrong is not academic — nmap's -PE host discovery and countless CTF pwn challenges hinge on crafting a byte-perfect ICMP echo that a real kernel will accept.

Hints

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Validation Suite

main.c

Workspace 1.0

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