Description
Map the fixed next-header codes for hop-by-hop, routing, fragment, ESP, AH, and destination options.
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.
Map the fixed next-header codes for hop-by-hop, routing, fragment, ESP, AH, and destination options.
When to use this tool
Use IPv6 Extension Next Header Token when you need to decode or encode one explicit packet field.
How to use the tool and how it works
- Enter value. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read kind, extension. Inspect extension before interpreting the associated values.
Map the fixed next-header codes for hop-by-hop, routing, fragment, ESP, AH, and destination options. Code 59 becomes no-next-header; all other codes share upper-layer-or-unassigned.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| value | Value | Required. Safe integer; minimum 0; maximum 255. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| kind | Kind | Required. Text; maximum UTF-16 length 8192. |
| extension | Extension | Required. Boolean. |
{
"input": {
"value": 44
},
"output": {
"kind": "fragment",
"extension": true
}
}Limitations and assumptions
- The extension flag follows this small table; the fallback does not mean an assigned upper-layer protocol is invalid.
- 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
Similar or alternative tools
- DNS Header Rcode Low Bits
Return the low four bits of flags as rcode.
- DNS Opcode Header Bit Extractor
Extract bits 11-14 of headerWord as opcode and its top bit as response.