Chapter 13 Firewall Screens
ZyWALL 5/35/70 Series User’s Guide
253
Figure 143 Blocking All LAN to WAN IRC Traffic Example
Your firewall would have the following configuration.
• 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 traffic from the LAN to go to
the WAN.
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 default 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. 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,
• or you configure a static DHCP entry for it so the ZyWALL always assigns it the same IP
address (see Section 7.3 on page 155 for information on static DHCP).
Now you configure a LAN to WAN firewall rule that allows IRC traffic from the IP address of
the CEO’s computer (192.168.1.7 for example) to go to any destination address. You do not
need to specify a schedule since you want the firewall rule to always be in effect. The
following figure shows the results of your two custom rules.
Table 67 Blocking All LAN to WAN IRC Traffic Example
# SOURCE
DESTINATIO
N
SCHEDULE SERVICE ACTION
1 Any Any Any IRC Drop
Default Any Any Any Any Allow
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