This Integer32, 0 to 65535, sets the age, in seconds, that a TCP half-open connection is tracked before it's aged out by the firewall. Admins tune this to control how quickly stale half-open connections are cleared, affecting both memory usage and how aggressively the firewall reacts to a slow-building SYN flood. For example, lowering hwAtkZoneSynFloodHalfAge to 10 seconds ages out incomplete handshakes faster during an active attack.