Redhat comes with its own firewall installed. To configure it, run setup. Then select firewall configuration. Then select high, medium or none for security. Then select customize. From here select which ports you want open. This depends on what you are doing. In addition, if you are running samba, you want to add the following in other ports exactly as listed: 137:tcp, 137:udp, 138:tcp, 138:udp, 139:tcp, 139:udp When finished, exit out of setup