Transmission Control Protocol

For information about Transmission Control Protocol (TCP) headers, see the following table.

For the TCP specification, see RFC793 available at http://⁠www.rfc-editor.org.

Table 1. TCP datagram
bits 0–7 bits 8–15 bits 16–23 bits 24–31

Source Port Number

(16 bits)

Destination Port Number

(16 bits)

Sequence Number

(32 bits)

Acknowledgment Number

(32 bits)

TCP Header Length

(4 bits)

Reserved

(6 bits)

URG

ACK

PSH

RST

SYN

FIN

Window Size

(16 bits)

Checksum

(16 bits)

Urgent Pointer

(16 bits)

Options (if any)

+

Padding (matching to 32-bit boundary)

( data . . . )