Chapter 18 Firewall
NXC5200 User’s Guide
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• The NXC applies NAT (Destination NAT) settings before applying the firewall
rules. So for example, if you configure a NAT entry that sends WAN traffic to a
LAN IP address, when you configure a corresponding firewall rule to allow the
traffic, you need to set the LAN IP address as the destination.
• The ordering of your rules is very important as rules are applied in sequence.
Figure 113
Configuration > Firewall
The following table describes the labels in this screen.
Table 92
Configuration > Firewall
LABEL
DESCRIPTION
General
Settings
Enable
Firewall
Select this check box to activate the firewall. The NXC performs access
control when the firewall is activated.
Allow
Asymmetrical
Route
If an alternate gateway on the LAN has an IP address in the same subnet
as the NXC’s LAN IP address, return traffic may not go through the NXC.
This is called an asymmetrical or “triangle” route. This causes the NXC to
reset the connection, as the connection has not been acknowledged.
Select this check box to have the NXC 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 NXC. A better
solution is to use virtual interfaces to put the NXC and the
backup gateway on separate subnets.