Terminology Index

Glossary

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Connection State

Whether and how a network connection is established and tracked, such as the stages of a TCP connection, which lets firewalls and analysts reason about traffic as conversations rather than isolated packets.

Connection-oriented protocols like TCP move through states (establishing, established, closing), and tracking this state is what lets a stateful firewall allow return traffic for a connection it permitted while blocking unsolicited packets. For defenders, understanding connection state aids investigation, distinguishing a completed conversation from a half-open scan, and is foundational to interpreting network evidence and firewall behavior.

Introduced in: Networking Foundations

Examples

  • A stateful firewall allowing return traffic because it tracks the connection's state.
  • Recognizing a flood of half-open connections as a scan or SYN flood.
  • Using connection state in logs to tell a completed session from a blocked attempt.