Filter
Top Products
Chapter 19 Firewall
ZyWALL USG 1000 User’s Guide
282
Your firewall would have the following configuration.
• The first row allows the LAN computer at IP address 192.168.1.7 to access the IRC
service on the WAN.
• The second row blocks LAN access to the IRC service on the WAN.
• The third row is (still) the firewall’s default policy of allowing all traffic from the LAN to
go to the WAN.
Alternatively, you configure a LAN to WAN rule with the CEO’s user name (say CEO) to
allow IRC traffic from any source IP address to go to any destination address.
Your firewall would have the following configuration.
• The first row allows any LAN computer to access the IRC service on the WAN by logging
into the ZyWALL with the CEO’s user name.
• The second row blocks LAN access to the IRC service on the WAN.
• The third row is (still) the firewall’s default policy of allowing all traffic from the LAN to
go to the WAN.
The rule for the CEO must come before the rule that blocks all LAN to WAN IRC traffic. If
the rule that blocks all LAN to WAN IRC traffic came first, the CEO’s IRC traffic would
match that rule and the ZyWALL would drop it and not check any other firewall rules.
19.4 Alerts
You can choose to generate an alert or log when a rule is matched and have the ZyWALL send
an immediate e-mail message to you. Otherwise, see the logs created (for the categories you
specified) in the View Log screen. Refer to the chapter on logs for details.
19.5 Asymmetrical Routes
If an alternate gateway on the LAN has an IP address in the same subnet as the ZyWALL’s
LAN IP address, return traffic may not go through the ZyWALL. This is called an
asymmetrical or “triangle” route. This causes the ZyWALL to reset the connection, as the
connection has not been acknowledged.
Table 86 Limited LAN to WAN IRC Traffic Example 1
# USER SOURCE
DESTINATIO
N
SCHEDULE SERVICE ACTION
1 Any 192.168.1.7 Any Any IRC Allow
2 Any Any Any Any IRC Deny
Default Any Any Any Any Any Allow
Table 87 Limited LAN to WAN IRC Traffic Example 2
# USER SOURCE
DESTINATIO
N
SCHEDULE SERVICE ACTION
1 CEO Any Any Any IRC Allow
2 Any Any Any Any IRC Deny
Default Any Any Any Any Any Allow