ZyXEL Communications ZYWALL10 - Manual (Page 175)

ZyWALL 10 Internet Security Gateway
14-6 Introducing the ZyWALL Firewall
Figure 14-5 Big Picture — Filtering, Firewall and NAT
14.3 Packet Filtering Vs Firewall
Below are some comparisons between the ZyWALL’s filtering and firewall functions.
14.3.1 Packet Filtering:
! The router filters packets as they pass through the router’s interface according to the filter rules you
designed.
! Packet filtering is a powerful tool, yet can be complex to configure and maintain, especially if you need
a chain of rules to filter a service.
! Packet filtering only checks the header portion of an IP packet.