Novell LINUX ENTERPRISE SERVER 10 - INSTALLATION AND ADMINISTRATION 11-05-2007 Installation Manual page 840

be used to put an additional line of defense in front of the internal network, because
the DMZ systems are isolated from the internal network.
Any kind of network traffic not explicitly allowed by the filtering rule set is suppressed
by iptables. Therefore, each of the interfaces with incoming traffic must be placed into
one of the three zones. For each of the zones, define the services or protocols allowed.
The rule set is only applied to packets originating from remote hosts. Locally generated
packets are not captured by the firewall.
The configuration can be performed with YaST (see
Firewall with YaST"
sysconfig/SuSEfirewall2, which is well commented. Additionally, a number
of example scenarios are available in /usr/share/doc/packages/
SuSEfirewall2/EXAMPLES.
43.4.1 Configuring the Firewall with YaST
IMPORTANT: Automatic Firewall Configuration
After the installation, YaST automatically starts a firewall on all configured in-
terfaces. If a server is configured and activated on the system, YaST can modify
the automatically-generated firewall configuration with the options Open Ports
on Selected Interface in Firewall or Open Ports on Firewall in the server configu-
ration modules. Some server module dialogs include a Firewall Details button
for activating additional services and ports. The YaST firewall configuration
module can be used to activate, deactivate, or reconfigure the firewall.
The YaST dialogs for the graphical configuration can be accessed from the YaST
Control Center. Select Security and Users > Firewall. The configuration is divided into
seven sections that can be accessed directly from the tree structure on the left side.
Start-Up
Set the start-up behavior in this dialog. In a default installation, SuSEfirewall2 is
started automatically. You can also start and stop the firewall here. To implement
your new settings in a running firewall, use Save Settings and Restart Firewall
Now.
822 Installation and Administration
(page 822)). It can also be made manually in the file /etc/
Section 43.4.1, "Configuring the