ZyXEL P-660HW-T1 User Manual download pdf (Page 149)

P-660H/HW/W-T Series User’ Guide

149 Chapter 11 Firewall Configuration

Figure 61 Firewall: Anti Probing

The following table describes the labels in this screen.

11.12 DoS Thresholds

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.

Refer to Section 11.12.3 on page 151 to configure thresholds.

Table 43 Firewall: Anti Probing

LABEL DESCRIPTION

Respond to PING

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.

Otherwise select LAN & WAN to reply to both incoming LAN and 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.

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ZyXEL P-660HW-T1 User Manual Page 149