ZyXEL Communications P-660RU-T1 v3, User Manual, Page: 110 / 230

Chapter 13 Firewall
P-660RU-Tx v3 User’s Guide
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LAND Attack
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
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.
SPI
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.
13.2 The Firewall Screen
Use this screen to enable firewall and/or SPI. Click Advanced Setup > Firewall to display the
following screen.
Figure 44 Advanced Setup > Firewall
The following table describes the labels in this screen.
1
Enabling SPI blocks all traffic initiated from the WAN side, including the DMZ,
virtual server and ACL on the WAN side.
Table 32 Advanced > Firewall
LABEL DESCRIPTION
Firewall Use this field to enable or disable firewall on your ZyXEL Device.
SPI Use this field to enable or disable SPI on your ZyXEL Device.
SAVE Click this to save your changes.
CANCEL Click this to restore your previously saved settings.