Configuring Firewall Thresholds - ZyXEL Communications P-660HW-Tx v3 Series User Manual

Type of traffic for certain servers.
5
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 ZyXEL Device may classify
them as DoS attacks.

10.4.2 Configuring Firewall Thresholds

The ZyXEL Device also sends alerts whenever TCP Maximum Incomplete is
exceeded. The global values specified for the threshold and timeout apply to all
TCP connections.
Click Firewall > Threshold to bring up the next screen.
Figure 83 Security > Firewall > Threshold
The following table describes the labels in this screen.
Table 57 Security > Firewall > Threshold
LABEL
Denial of Service
Thresholds
One Minute Low
P-660HW-Tx v3 Series User's Guide
DESCRIPTION
The ZyXEL Device measures both the total number of existing half-
open sessions and the rate of session establishment attempts. Both
TCP and UDP half-open sessions are counted in the total number and
rate measurements. Measurements are made once a minute.
This is the rate of new half-open sessions per minute that causes the
firewall to stop deleting half-open sessions. The ZyXEL Device
continues to delete half-open sessions as necessary, until the rate of
new connection attempts drops below this number.
Chapter 10 Firewalls
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