ZyXEL ZyWALL 5 User Guide - Page 255

Chapter 13 Firewall Screens Figure 145 SECURITY > FIREWALL > Default Rule (Router Mode) The following table describes the labels in this screen. Table 69 SECURITY > FIREWALL > Default Rule (Router Mode) LABEL DESCRIPTION 0-100% This bar displays the percentage of the ZyWALL's firewall rules storage space that is currently in use. When the storage space is almost full, you should consider deleting unnecessary firewall rules before adding more firewall rules. Enable Firewall Select this check box to activate the firewall. The ZyWALL performs access control and protects against Denial of Service (DoS) attacks when the firewall is activated. Allow Asymmetrical Route Note: When you activate the firewall, all current connections through the ZyWALL are dropped when you apply your changes. If an alternate gateway on the LAN has an IP address in the same subnet as the ZyWALL's LAN IP address, return traffic may not go through the ZyWALL. This is called an asymmetrical or "triangle" route. This causes the ZyWALL to reset the connection, as the connection has not been acknowledged. Select this check box to have the ZyWALL permit the use of asymmetrical route topology on the network (not reset the connection). Note: Allowing asymmetrical routes may let traffic from the WAN go directly to the LAN without passing through the ZyWALL. A better solution is to use IP alias to put the ZyWALL and the backup gateway on separate subnets. See Section 13.9 on page 271 for an example. ZyWALL 5/35/70 Series User's Guide 255