TCP SYN Flood
A SYN flood exhausts connection-handling resources by creating many TCP connection attempts that do not complete normally.
Mechanism
The server receives many SYN packets and must maintain state while waiting for the handshake to complete. Defenses reduce state pressure or filter abnormal sources.
Indicators to watch
High SYN rates, high SYN-to-established ratios, backlog pressure, retransmission anomalies, and service latency.
Concept diagram
Defensive controls
Use SYN cookies, backlog tuning, upstream DDoS protection, rate controls, and network telemetry.
Recommended security control
Firewall / DDoS protection
Generate traffic only in an authorized performance lab.
Defense tool
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All attack descriptions are for defensive education. Test scanning, traffic generation, interception, wireless testing, and vulnerable applications only on systems and networks you own or are explicitly authorized to assess.