Read the IPv4 header
02Version, header length, length, lifetime, protocol, addresses, and a header checksum describe the packet.
Related RFCs and changes
“Updates” changes part of an earlier RFC. “Obsoletes” replaces it. This list shows selected related documents.
DIAGRAM§ 3.1 ↗
RFC 791 · § 3.1EXAMPLE
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03
Check header integrity separately from payload integrity.
Check header integrity separately from payload integrity.
Protocol participantThreat or exceptionProtocol controlSimplified drawings · precise section references
Read the updated RFC section ↗
IHL counts 32-bit header words; Total Length includes header and data.
- IHL counts 32-bit header words; Total Length includes header and data.
- The header checksum covers the header, not the application payload.
The drawing is a simplified worked example. Follow the linked RFC and its updates for implementation requirements.
Read the RFC section ↗Diagrams simplify the RFC. Read the linked sections for complete requirements.
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