Allied Telesis AR450S Manual de usuario descargar pdf (Pagina 19)

How to configure the AT-AR450S Firewall using the Graphical User Interface (GUI) 19

C613-16011-00 REV A

13 February 2004

Understanding the firewall’s behaviour

This section gives extra information to support the GUI configuration description,

because to understand which rules you need to create, you need to understand the

default behaviour of the firewall and firewall policies. The default behaviour of the firewall

policies is as follows:

■ Traffic from the public side (WAN) to the private side (LAN) is always denied unless

specifically allowed.

■ Traffic from the private side (LAN) to the public side (WAN) is always allowed unless

specifically denied.

■ If a policy has multiple public interfaces, then the default behaviour is to allow traffic

that arrives at one public interface destined for an address beyond the other public

interface.

The initial configuration created by the GUI has two policies:

■ A LAN policy.

Private interface LAN and public interfaces WAN and DMZ.

■ A DMZ policy.

Private interface DMZ and public interfaces LAN and WAN.

These policies correspond to the following firewall commands.

Given the default behaviour of the firewall, the default behaviour of traffic going to and

from the LAN and DMZ policies can be summarised as shown in Table 4 on page 19, and

Table 5 on page 20.

enable firewall

create firewall policy="guidmz"

create firewall policy="guilan"

add firewall policy="guidmz" int=eth1 type=private

add firewall policy="guidmz" int=vlan1 type=public

add firewall policy="guidmz" int=eth0 type=public

add firewall policy="guilan" int=vlan1 type=private

add firewall policy="guilan" int=eth1 type=public

add firewall policy="guilan" int=eth0 type=public

Ta b l e 4 : L A N Po l i c y

To To To

From

LAN - Private DMZ - Public WAN - Public

LAN - Private Not applicable Allow Allow

DMZ - Public Disallow Not applicable Allow

WAN - Public Disallow Allow Not applicable

1 2 ... 14 15 16 17 18 19 20

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Allied Telesis AR450S Manual de usuario Pagina 19