Chapter 18 Firewall; Overview; What You Can Do In This Chapter - ZyXEL Communications NXC5200 User Manual

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H A P T E R

18.1 Overview

Use the firewall to block or allow services that use static port numbers. Use
application patrol to control services using flexible/dynamic port numbers. The
firewall can also limit the number of user sessions.
This figure shows the NXC's default firewall rules in action and demonstrates how
stateful inspection works. Administrator 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 WLAN zone and destined for the LAN zone is
blocked. Communications from the WLAN through the LAN to the WAN is allowed.
Figure 110 Default Firewall Action

18.1.1 What You Can Do in this Chapter

• The Firewall screens
and asymmetrical routes, and manage and configure firewall rules.
• The Session Limit screens
concurrent NAT/firewall sessions a client can use.
NXC5200 User's Guide
(Section 18.2 on page 257) enable or disable the firewall
(Section 18.3 on page
18
Firewall
262) limit the number of
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