Chapter 10 Firewalls

5Type 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 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

DESCRIPTION

Denial of Service

The ZyXEL Device measures both the total number of existing half-

Thresholds

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.

 

 

One Minute Low

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.

 

 

 

203

P-660HW-Tx v3 Series User’s Guide