Firewall; Chapter 20 Firewall; Overview; What You Can Do In The Firewall Screens - ZyXEL Communications ZYWALL USG 2000 Manual

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H A P T E R

20.1 Overview

Use the firewall to block or allow services that use static port numbers. Use
application patrol (see
dynamic port numbers.
This figure shows the ZyWALL's default firewall rules in action and 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. The firewall
allows VPN traffic between any of the networks.
Figure 203 Default Firewall Action

20.1.1 What You Can Do in the Firewall Screens

• Use the Firewall screen
firewall and asymmetrical routes, set a maximum number of sessions per host,
and display the configured firewall rules.
ZyWALL USG 2000 User's Guide
Chapter 28 on page 445) to control services using flexible/
(Section 20.2 on page
20

Firewall

328) to enable or disable the
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