ZyXEL Communications Corporation P660HNT1AV2 Manuel D’Utilisation

P-660HN-Tx(A) v2 User’s Guide

This chapter shows you how to enable the ADSL Router firewall. Use the firewall to protect your 
ADSL Router and network from attacks by hackers on the Internet and control access to it. 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.
• blocks SYN and port scanner attacks.

By default, the ADSL Router blocks DDOS, LAND and Ping of Death attacks whether the firewall is 
enabled or disabled.

The following figure illustrates the 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).

Default Firewall Action

• Use  the  General screen (

) to select the firewall protection level on the 

ADSL Router.

• Use  the  Default Action screen (

) to set the default action that the 

firewall takes on packets that do not match any of the firewall rules.

• Use  the  Rules screen (

) to view the configured firewall rules and add, 

edit or remove a firewall rule.

• Use  the  Dos screen (

) to set the thresholds that the ADSL Router uses 

to determine when to start dropping sessions that do not become fully established (half-open 
sessions).

3
4

1
2