ZyXEL Communications P-660RU-Tx 用户手册

Chapter 13 Firewall

P-660RU-Tx User’s Guide

device or network so users no longer have access to network resources. The 
ZyXEL Device is pre-configured to automatically detect and thwart all known DoS 
attacks.

A DDoS attack is one in which multiple compromised systems attack a single 
target, thereby causing denial of service for users of the targeted system.

In a LAND attack, hackers flood SYN packets into the network with a spoofed 
source IP address of the target system. This makes it appear as if the host 
computer sent the packets to itself, making the system unavailable while the 
target system tries to respond to itself.

Ping of Death uses a "ping" utility to create and send an IP packet that exceeds 
the maximum 65,536 bytes of data allowed by the IP specification. This may 
cause systems to crash, hang or reboot.

Stateful Packet Inspection (SPI) tracks each connection crossing the firewall and 
makes sure it is valid. Filtering decisions are based not only on rules but also 
context. For example, traffic from the WAN may only be allowed to cross the 
firewall in response to a request from the LAN.

Use this screen to enable firewall and/or SPI. Click Advanced Setup > Firewall 
to display the following screen.

Figure 44   Advanced Setup > Firewall