User guide

SmartDefense Categories
Chapter 11: Using SmartDefense 223
TCP
This category allows you to configure various protections related to the TCP protocol. It
includes the following:
• Flags on page
229
• Sequence Verifier on page
228
• Small PMTU on page
224
• Strict TCP on page
223
• SynDefender on page
226
Strict TCP
Out-of-state TCP packets are SYN-ACK or data packets that arrive out of order, before the
TCP SYN packet.
Note: In normal conditions, out-of-state TCP packets can occur after the ZoneAlarm
restarts, since connections which were established prior to the reboot are unknown.
This is normal and does not indicate an attack.
You can configure how out-of-state TCP packets should be handled.