Description
Check IP version 4 or 6 and a 16-bit checksum.
A UDP checksum word and the UDP length field serve different purposes: one detects corruption, while the other counts header plus payload bytes. IP version affects checksum policy.
Check IP version 4 or 6 and a 16-bit checksum.
When to use this tool
Use Network: UDP Zero Checksum Version Policy when you need to inspect a supplied UDP length or checksum convention.
How to use the tool and how it works
- Enter ipVersion, checksum, explicitIpv6Exception. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read result. Expand result to inspect the returned fields.
Check IP version 4 or 6 and a 16-bit checksum. A nonzero checksum is generally allowed; zero is generally allowed only for IPv4. Mark a declared IPv6 exception separately.1
IPv6 zero-checksum use has narrowly specified tunnel exceptions. Declaring an exception here records that assertion; it does not establish the required protections or applicability.2
| Input field | Meaning and units | Accepted input |
|---|---|---|
| ipVersion | Ip Version | Required. Safe integer. |
| checksum | Checksum | Required. Safe integer. |
| explicitIpv6Exception | Explicit Ipv6 Exception | Required. Boolean. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| result | Result | Required. Object. |
| result.zeroChecksum | Zero Checksum | Calculated result member: boolean. |
| result.generallyAllowed | Generally Allowed | Calculated result member: boolean. |
| result.requiresSpecifiedException | Requires Specified Exception | Calculated result member: boolean. |
| result.explicitExceptionDeclared | Explicit Exception Declared | Calculated result member: boolean. |
{
"input": {
"ipVersion": 6,
"checksum": 0,
"explicitIpv6Exception": false
},
"output": {
"result": {
"zeroChecksum": true,
"generallyAllowed": false,
"requiresSpecifiedException": true,
"explicitExceptionDeclared": false
}
}
}Limitations and assumptions
- The exception flag records the caller's assertion; it does not verify that a protocol-specific exception applies or check checksum correctness.
- 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
Use packet capture and a complete datagram checksum verifier for end-to-end validation.
References
Similar or alternative tools
- UDP Checksum Negative Zero Transmit Word
Accept a computed 16-bit checksum and replace zero with 65535; return every other word unchanged.
- Network: UDP Length Payload Crosswalk
Subtract the fixed eight-byte header from udpLength, which must be an integer from 8 through 65535.