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Network: Arp Opcode Single Field Label Tool

Label the four base ARP/RARP operation codes from RFC826/RFC903 while preserving other sixteen-bit opcodes as other; not packet validation or a complete IANA registry.

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Description

Label opcodes 1-4 as ARP-request, ARP-reply, RARP-request, and RARP-reply.

Packet headers encode several meanings in fixed-width fields. Bit positions, network byte order, and reserved values must be distinguished from validation of an entire message.

Label opcodes 1-4 as ARP-request, ARP-reply, RARP-request, and RARP-reply.

When to use this tool

Use Network: Arp Opcode Single Field Label when you need to decode or encode one explicit packet field.

How to use the tool and how it works

  1. Enter opcode. Use the units and conventions below.
  2. Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
  3. Read result. Expand result to inspect the returned fields.

Label opcodes 1-4 as ARP-request, ARP-reply, RARP-request, and RARP-reply. Return other for all remaining 16-bit values.1

Input fieldMeaning and unitsAccepted input
opcodeOpcodeRequired. Safe integer.
Output fieldInterpretationReturned shape
resultResultRequired. Object.
result.nameNameCalculated result member: string.
result.recognizedBaseOperationRecognized Base OperationCalculated result member: boolean.
json
{
  "input": {
    "opcode": 2
  },
  "output": {
    "result": {
      "name": "ARP-reply",
      "recognizedBaseOperation": true
    }
  }
}

Limitations and assumptions

  • The recognized flag covers only this base table, not the complete registry or a valid ARP packet.
  • Outputs are nested inside result. Inputs must satisfy both the field types and the cross-field conditions above. Invalid input causes an error; a successful false flag or documented placeholder is a different result.
  • Numeric calculations use binary floating point unless exact decimal-integer arithmetic is explicitly stated. No hidden measurement tolerance or decimal rounding is added; nonfinite or out-of-contract results are rejected. Numeric signed-zero results are exported as zero.

Alternative or Complementary methods

Inspect the complete captured header and apply the relevant protocol's structural and state rules.

References

  1. Calculation and input contract: network/arp-opcode-single-field-label — tool.io

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