Table of Contents
Advertisement
15.1 Overview
This chapter shows you how to enable and configure the ZyXEL Device firewall. Use the firewall to
protect your ZyXEL Device and network from attacks by hackers on the Internet and control access
to it. By default the firewall:
• allows traffic that originates from your LAN computers to go to all other networks.
• blocks traffic that originates on other networks from going to the LAN.
The following figure illustrates the default firewall action. User A can initiate an IM (Instant
Messaging) session from the LAN to the WAN (1). Return traffic for this session is also allowed (2).
However other traffic initiated from the WAN is blocked (3 and 4).
Figure 89 Default Firewall Action
LAN
A
15.1.1 What You Can Do in this Chapter
• Use the Firewall screen to configure the security level of the firewall on the ZyXEL Device
(Section 15.2 on page
• Use the Protocol screen to add or remove predefined Internet services and configure firewall
rules
(Section 15.3 on page
• Use the Access Control screen to view and configure incoming/outgoing filtering rules
15.4 on page
15.1.2 What You Need to Know
SYN Attack
A SYN attack floods a targeted system with a series of SYN packets. Each packet causes the
targeted system to issue a SYN-ACK response. While the targeted system waits for the ACK that
P-873HNUP-51B User's Guide
1
2
197).
197).
200).
C
HAPTER
WAN
3
4
1 5
Firewall
(Section
195
Advertisement
Table of Contents
