ZyXEL Communications Prestige 662HW Series, Руководство пользователя

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Prestige 662HW Series User’s Guide
12-18 Firewall Configuration
Figure 12-13 Firewall: Anti-Probing
The following table describes the labels in this screen.
Table 12-7 Firewall: Anti-Probing
LABEL DESCRIPTION
Respond to PING
on The Prestige does not respond to any incoming Ping requests when Disable is
selected.
Select LAN to reply to incoming LAN Ping requests.
Select WAN to reply to incoming WAN Ping requests.
Select LAN & WAN to replay incoming LAN or WAN Ping requests.
Do not respond to
requests for
unauthorized
services. Select this option to prevent hackers from finding the Prestige by probing for unused
ports. If you select this option, the Prestige will not respond to port request(s) for
unused ports, thus leaving the unused ports and the Prestige unseen. By default this
option is not selected and the Prestige will reply with an ICMP Port Unreachable packet
for a port probe on its unused UDP ports, and a TCP Reset packet for a port probe on
its unused TCP ports.
Note that the probing packets must first traverse the Prestige 's firewall mechanism
before reaching this anti-probing mechanism. Therefore if the firewall mechanism
blocks a probing packet, the Prestige reacts based on the firewall policy, which by
default, is to send a TCP reset packet for a blocked TCP packet. You can use the
command "sys firewall tcprst rst [on|off]" to change this policy. When the firewall
mechanism blocks a UDP packet, it drops the packet without sending a response
packet.
Back Click Back to return to the previous screen.
Apply Click Apply to save your changes back to the Prestige.
Reset
Click Reset to begin configuring this screen afresh.
12.12 Configuring Attack Alert
Attack alerts are the first defense against DOS attacks. In the Threshold screen, shown later, you may
choose to generate an alert whenever an attack is detected. For DoS attacks, the Prestige uses
thresholds to determine when to drop sessions that do not become fully established. These thresholds
apply globally to all sessions.
You can use the default threshold values, or you can change them to values more suitable to your
security requirements.