Bits such as SYN, ACK, FIN, and RST that convey control information in a TCP segment.
Control bits carried in the TCP segment header. SYN opens a connection, ACK acknowledges receipt, FIN closes a connection cleanly, and RST aborts it -- combinations of these flags represent the connection's state transitions. When investigating a dropped connection via packet capture, whether an RST was sent back is an important clue.
© 2026 ITBGM