During the Red Hat Linux installation, you are given the option to choose high,
medium or no security level as well as allow specific devices, incoming
services, and ports. These levels are based on the
GNOME Lokkit firewall configuration
application.
After installation, you can change the security level of your
system by using GNOME Lokkit.
GNOME Lokkit allows you to configure firewall settings for
an average user by constructing basic ipchains
networking rules. Instead of having to write the rules, this program asks
you a series of questions about how you use your system and then write it
for you in the file /etc/sysconfig/ipchains.
You should not try to use GNOME Lokkit to
generate complex firewall rules. It is intended for average users who want
to protect themselves while using a modem, cable, or DSL Internet
connection. To configure specific firewall rules, refer to the
Firewalling with iptables
chapter in the Official Red Hat Linux Reference Guide.
To disable specific services and deny specific hosts and users, refer to
Chapter 8.
To start GNOME Lokkit, type the command
gnome-lokkit at a shell prompt as root.
After starting the program, choose the appropriate security level for
your system:
High Security — This option disables
almost all network connects except DNS replies and DHCP so that
network interfaces can be activated. IRC, ICQ, and other instant
messaging services as well as RealAudioTM will
not work without a proxy.
Low Security — This option will not allow remote
connections to the system, including NFS connections and remote X Window
System sessions. Services that run below port 1023 will not accept
connections, including FTP, SSH, Telnet, and HTTP.
Disable Firewall — This option does not
create any security rules. It is recommended that this option only
be chosen if the system is on a trusted network (not on the
Internet), if the system is behind a larger firewall, or if
you write your own custom firewall rules. If you choose this option
and click Next, proceed to
the section called Activating the Firewall. The security of your system will
not be changed.
