Chapter 15 Firewall Configuration
Figure 149 Firewall Example: Rules: MyService
15.8 DoS Thresholds
For DoS attacks, the ZyXEL Device uses thresholds to determine when to drop sessions that do not become fully established. These thresholds apply globally to all sessions.
You can use the default threshold values, or you can change them to values more suitable to your security requirements.
Refer to Section 15.8.3 on page 260 to configure thresholds.
15.8.1 Threshold Values
Tune these parameters when something is not working and after you have checked the firewall counters. These default values should work fine for most small offices. Factors influencing choices for threshold values are:
•The maximum number of opened sessions.
•The minimum capacity of server backlog in your LAN network.
•The CPU power of servers in your LAN network.
•Network bandwidth.
•Type of traffic for certain servers.
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), then the default values should be reduced.
You should make any changes to the threshold values before you continue configuring firewall rules.
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