User's Manual

NXC CLI Reference Guide
119
CHAPTER 19
Firewall
This chapter introduces the NXC’s firewall and shows you how to configure your NXC’s
firewall.
19.1 Firewall Overview
The NXC’s firewall is a stateful inspection firewall. The NXC restricts access by screening
data packets against defined access rules. It can also inspect sessions. For example, traffic
from one zone is not allowed unless it is initiated by a computer in another zone first.
A zone is a group of interfaces. Group the NXC’s interfaces into different zones based on your
needs. You can configure firewall rules for data passing between zones or even between
interfaces in a zone.
The following figure shows the NXC’s default firewall rules in action as well as demonstrates
how stateful inspection works. User 1 can initiate a Telnet session from within the LAN zone
and responses to this request are allowed. However, other Telnet traffic initiated from the
WAN or DMZ zone and destined for the LAN zone is blocked. Communications between the
WAN and the DMZ zones are allowed.
Figure 13 Default Firewall Action