What You Need To Know - ZyXEL Communications ZyWALL USG 200 Series User Manual

Chapter 24 Firewall

24.1.2 What You Need to Know

Stateful Inspection
The ZyWALL has a stateful inspection firewall. The ZyWALL restricts access by
screening data packets against defined access rules. It also inspects sessions. For
example, traffic from one zone is not allowed unless it is initiated by a computer in
another zone first.
Zones
A zone is a group of interfaces or VPN tunnels. Group the ZyWALL's interfaces into
different zones based on your needs. You can configure firewall rules for data
passing between zones or even between interfaces and/or VPN tunnels in a zone.
Default Firewall Behavior
Firewall rules are grouped based on the direction of travel of packets to which they
apply. Here is the default firewall behavior for traffic going through the ZyWALL in
various directions.
Table 117 Default Firewall Behavior
FROM ZONE TO ZONE
From WAN to ZyWALL
From WAN to any (other
than the ZyWALL)
From DMZ to ZyWALL
From DMZ to any (other
than the ZyWALL)
From WLAN to WAN
From WLAN to ZyWALL
From WLAN to any
(other than the ZyWALL)
From ANY to ANY
454
BEHAVIOR
Traffic from the WAN to the ZyWALL itself is allowed for certain
default services described in
other WAN to ZyWALL traffic is dropped.
Traffic from the WAN to any of the networks behind the
ZyWALL is dropped.
Traffic from the DMZ to the ZyWALL itself is allowed for certain
default services described in
other DMZ to ZyWALL traffic is dropped.
Traffic from the DMZ to any of the networks behind the
ZyWALL is dropped.
Traffic from the WLAN to the WAN is allowed.
Traffic from the WLAN to the ZyWALL itself is allowed for
certain default services described in
455. All other WLAN to ZyWALL traffic is dropped.
Traffic from the WLAN to any of the networks behind the
ZyWALL is dropped.
Traffic that does not match any firewall rule is allowed. So for
example, LAN to WAN, LAN to DMZ, and LAN to WLAN traffic is
allowed. This also includes traffic to or from interfaces or VPN
tunnels that are not assigned to a zone (extra-zone traffic).
ZyWALL USG 100/200 Series User's Guide
To-ZyWALL Rules on page
To-ZyWALL Rules on page
To-ZyWALL Rules on page
455. All
455. All