ZyXEL Communications P-2608HWL-Dx Series - Manual (Page 187)

P-2608HWL-Dx Series User’s Guide
Chapter 15 Firewalls 187
C
H A P T E R
15
Firewalls
This chapter gives some background information on firewalls and introduces the ZyXEL
Device firewall.
15.1 Firewall Overview
The networking term “firewall” is a system or group of systems that enforces an access-
control policy between two networks. It may also be defined as a mechanism used to protect a
trusted network from an untrusted network. Of course, firewalls cannot solve every security
problem. A firewall is one of the mechanisms used to establish a network security perimeter in
support of a network security policy. It should never be the only mechanism or method
employed. For a firewall to guard effectively, you must design and deploy it appropriately.
This requires integrating the firewall into a broad information-security policy. In addition,
specific policies must be implemented within the firewall itself.
Refer to Section 16.5 on page 202 to configure default firewall settings.
Refer to Section 16.6 on page 203 to view firewall rules.
Refer to Section 16.6.1 on page 205 to configure firewall rules.
Refer to Section 16.6.2 on page 208 to configure a custom service.
Refer to Section 16.8.3 on page 215 to configure firewall thresholds.
15.2 Types of Firewalls
There are three main types of firewalls:
• Packet Filtering Firewalls
• Application-level Firewalls
• Stateful Inspection Firewalls
15.2.1 Packet Filtering Firewalls
Packet filtering firewalls restrict access based on the source/destination computer network
address of a packet and the type of application.