ZyXEL Communications P-660HW-Tx v3 User Manual page 199

Click Firewall > Threshold to bring up the next screen.
Figure 67 Security > Firewall > Threshold
The following table describes the labels in this screen.
Table 50 Security > Firewall > Threshold
LABEL
Denial of Service
Thresholds
One Minute Low
One Minute High
Maximum
Incomplete Low
P-660HW-Tx v3 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.
This is the rate of new half-open sessions per minute that causes the
firewall to start deleting half-open sessions. When the rate of new
connection attempts rises above this number, the ZyXEL Device deletes
half-open sessions as required to accommodate new connection
attempts.
For example, if you set the one minute high to 100, the ZyXEL Device
starts deleting half-open sessions when more than 100 session
establishment attempts have been detected in the last minute. It stops
deleting half-open sessions when the number of session establishment
attempts detected in a minute goes below the number set as the one
minute low.
This is the number of existing half-open sessions that causes the
firewall to stop deleting half-open sessions. The ZyXEL Device
continues to delete half-open requests as necessary, until the number
of existing half-open sessions drops below this number.
Chapter 9 Firewalls
199