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Chapter 11 Firewall
ZyWALL 2WG User’s Guide
262
11.11.1 Threshold Values
If everything is working properly, you probably do not need to change the threshold settings as
the default threshold values should work for most small offices. Tune these parameters when
you believe the ZyWALL has been receiving DoS attacks that are not recorded in the logs or
the logs show that the ZyWALL is classifying normal traffic as DoS attacks. Factors
influencing choices for threshold values are:
1 The maximum number of opened sessions.
2 The minimum capacity of server backlog in your LAN network.
3 The CPU power of servers in your LAN network.
4 Network bandwidth.
5 Type of traffic for certain servers.
Reduce the threshold values if your network is slower than average for any of these factors
(especially if you have servers that are slow or handle many tasks and are often busy).
If you often use P2P applications such as file sharing with eMule or eDonkey, it’s
recommended that you increase the threshold values since lots of sessions will be established
during a small period of time and the ZyWALL may classify them as DoS attacks.
11.12 Threshold Screen
Click SECURITY > FIREWALL > Threshold to bring up the next screen. The global
values specified for the threshold and timeout apply to all TCP connections.
Figure 162 SECURITY > FIREWALL > Threshold