ZyXEL Communications ZyWall USG 2000 User Manual page 313

Unified security gateway

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the firewall rule to always be in effect. The following figure shows the results of

Figure 197 Blocking All LAN to WAN IRC Traffic Example

Your firewall would have the following rules.

Table 97 Blocking All LAN to WAN IRC Traffic Example

• The first row blocks LAN access to the IRC service on the WAN.

• The second row is the firewall's default policy that allows all LAN to WAN traffic.

The ZyWALL applies the firewall rules in order. So for this example, when the

ZyWALL receives traffic from the LAN, it checks it against the first rule. If the

traffic matches (if it is IRC traffic) the firewall takes the action in the rule (drop)

and stops checking the firewall rules. Any traffic that does not match the first

firewall rule will match the second rule and the ZyWALL forwards it.

Now suppose that your company wants to let the CEO use IRC. You can configure

a LAN to WAN firewall rule that allows IRC traffic from the IP address of the CEO's

computer. You can also configure a LAN to WAN rule that allows IRC traffic from

any computer through which the CEO logs into the ZyWALL with his/her user

name. In order to make sure that the CEO's computer always uses the same IP

address, make sure it either:

• Has a static IP address,

• You configure a static DHCP entry for it so the ZyWALL always assigns it the

same IP address (see

ZyWALL USG 2000 User's Guide

DHCP Settings on page 222

Chapter 20 Firewall

SCHEDULE SERVICE

for information on DHCP).

Troubleshooting

Zywall usg 1000