Chapter 25 Firewall
UAG4100 User’s Guide
250
Figure 174 Blocking All LAN to WAN IRC Traffic Example
Your firewall would have the following rules.
• 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 LAN1 to WAN traffic.
The UAG applies the firewall rules in order. So for this example, when the UAG 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 UAG forwards it.
Now suppose you need to let the CEO use IRC. You configure a LAN1 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 UAG 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,
or
• You configure a static DHCP entry for it so the UAG always assigns it the same IP address (see
DHCP Settings on page 149 for information on DHCP).
Now you configure a LAN1 to WAN firewall rule that allows IRC traffic from the IP address of the
CEO’s computer (172.16.1.7 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 112 Blocking All LAN to WAN IRC Traffic Example
# USER SOURCE DESTINATION SCHEDULE SERVICE ACTION
1 Any Any Any Any IRC Deny
2 Any Any Any Any Any Allow
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