ZyXEL Communications P-660 series Guide de l'utilisateur télécharger pdf (Page 90)

Chapter 7 Firewalls

P-660R-F1 Series User’s Guide

The following table describes the labels in this screen.

7.3 The Firewall Rule Screen

Note: The ordering of your rules is very important as rules are applied in turn.

Table 31 Security > Firewall > General

LABEL DESCRIPTION

Active Firewall Select this check box to activate the firewall. The ZyXEL Device performs access

control and protects against Denial of Service (DoS) attacks when the firewall is

activated.

Bypass Triangle

Route

If an alternate gateway on the LAN has an IP address in the same subnet as the

ZyXEL Device’s LAN IP address, return traffic may not go through the ZyXEL

Device. This is called an asymmetrical or “triangle” route. This causes the ZyXEL

Device to reset the connection, as the connection has not been acknowledged.

Select this check box to have the ZyXEL Device permit the use of asymmetrical

route topology on the network (not reset the connection).

Note: Allowing asymmetrical routes may let traffic from the WAN go directly to the

LAN without passing through the ZyXEL Device. A better solution is to use

IP alias to put the ZyXEL Device and the backup gateway on separate

subnets. See Section 7.5.4.1 on page 101 for an example.

Packet Direction This is the direction of travel of packets (LAN to Router, LAN to WAN, WAN to

Router, WAN to LAN).

Firewall rules are grouped based on the direction of travel of packets to which

they apply. For example, LAN to Router means packets traveling from a

computer/subnet on the LAN to the ZyXEL Device itself.

Default Action Use the drop-down list boxes to select the default action that the firewall is to

take on packets that are traveling in the selected direction and do not match any

of the firewall rules.

Select Drop to silently discard the packets without sending a TCP reset packet or

an ICMP destination-unreachable message to the sender.

Select Reject to deny the packets and send a TCP reset packet (for a TCP

packet) or an ICMP destination-unreachable message (for a UDP packet) to the

sender.

Select Permit to allow the passage of the packets.

Log Select the check box to create a log (when the above action is taken) for packets

that are traveling in the selected direction and do not match any of your

customized rules.

Expand... Click this to display more information.

Basic... Click this to display less information.

Apply Click this to save your changes.

Cancel Click this to restore your previously saved settings.

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ZyXEL Communications P-660 series Guide de l'utilisateur Page 90

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