Headers & connections
02TCP headers identify endpoints and carry the sequence, acknowledgment, window, and control information that drive the connection.
Related RFCs and changes
“Updates” changes part of an earlier RFC. “Obsoletes” replaces it. This list shows selected related documents.
DIAGRAM§ 3.1 ↗
RFC 9293 · § 3.1EXAMPLE
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04
Apply stateful rules.
An arriving segment is interpreted according to the current connection state.
Protocol participantThreat or exceptionProtocol controlSimplified drawings · precise section references
Read the updated RFC section ↗
Each connection needs its own state.
- A connection is identified by its pair of sockets, each comprising an IP address and port.
- The checksum covers the TCP header, data, and an IP pseudo-header.
- Header options are variable length; the data offset locates the payload.
A checksum detects transmission corruption. It is not a cryptographic integrity or authenticity mechanism.
Read the RFC section ↗Diagrams simplify the RFC. Read the linked sections for complete requirements.
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