ZyXEL Communications P-794M, Руководство пользователя

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Prestige 794M User’s Guide
73 Chapter 6 Firewall
The following table describes the labels in this screen.
Note: For SYN Flood, ICMP Echo Storm and ICMP flood attacks, the Prestige logs
the event in the
Event Log screen. The Prestige cannot prevent such attacks
from occurring.
6.6 URL Filter
URL (Uniform Resource Locator) filtering allows you to create and enforce Internet access
policies tailored to your needs. URL filtering gives you the ability to block web sites that
contain key words (that you specify) in the web address (such as www.xxx.com). You can set
a schedule for when the Prestige performs content filtering.
Note: URL filter blocks web browser (HTTP) connection attempts using port 80 only.
Click Configuration , Firewall and URL Filter in the navigation panel to display the screen
as shown next.
Table 35 Firewall: Intrusion Detection
LABEL DESCRIPTION
Intrusion Detection Select Enable to activate this feature.
Select Disable to deactivate this feature.
Victim Protection
Block Duration
Specify the time period (in seconds) the Prestige blocks any Smurf attacks when
detected.
Scan Attack Block
Duration
Specify the time period (in seconds) the Prestige blocks hosts that attempt a
possible Scan attack. Scan attack types include X’mas scan, IMAP SYN/FIN scan
and similar attempts.
DoS Attack Block
Duration
Specify the time period (in seconds) the Prestige blocks hosts that attempt a
possible Denial of Service (DoS) attack.
Possible DoS attacks this attempts to block include
Ascend Kill and WinNuke.
Max TCP Open
Handshaking
Count
This is the rate of new TCP handshake open sessions that causes the firewall to
determine that this is a SYN Flood attack. The Prestige then starts to delete new
sessions.
Max PING Count This is the rate of ICMP echo (or Ping) requests that the Prestige receives per
second. If the current rate is above this number, the firewall decides that this is an
ICMP Echo Storm attack.
Max ICMP Count This is the rate of ICMP packets that the Prestige receives per second. If the
current rate is above this number, the firewall decides that this is an ICMP Flood
attack.
Apply Click Apply to save the settings.
Clear Blacklist Click Clear Blacklist to reset the blacklist.