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Implement an ARP Request using Raw Sockets

hard3/6

Craft a Custom UDP Packet from Scratch Capture All Traffic in Promiscuous Mode

Language

Compiler

2.0s Limit 256MB

Submit and pass all tests to enable saving to GitHub.

Implementation

Implement a C program that documents ARP request construction.

Requirements:

Define the ARP packet structure with all required fields
Set opcode to 1 (ARP request)
Set hardware type to 1 (Ethernet) and protocol type to 0x0800 (IPv4)
Set sender MAC and IP addresses
Leave target MAC as 00:00:00:00:00:00 and set target IP
Wrap the ARP packet in an Ethernet frame with broadcast destination
Print every field with its name and value
Explain why broadcast is used for the request

Success Criteria:

ARP fields are labeled and printed
Opcode 1 (request) is clearly shown
Broadcast MAC address is documented
Output contains the keywords: ARP, request, MAC, broadcast

Why This Matters

RFC 826 defines exactly the 28-byte layout you're building, and tools like arping and arp-scan send this same broadcast frame to discover hosts on a LAN. The lack of authentication in ARP is also why ettercap and arpspoof can perform man-in-the-middle attacks simply by broadcasting forged replies that poison a victim's ARP cache.

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Validation Suite

main.c

Workspace 1.0

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