Other Ports179or IMAP, or if you use a tool such as fetchmail. To allow delivery of mail to your machine, selectthis check box. Note that an improperly configured SMTP server can allow remote machines touse your server to send spam.NFS4The Network File System (NFS) is a file sharing protocol commonly used on *NIX systems.Version 4 of this protocol is more secure than its predecessors. If you want to share files ordirectories on your system with other network users, select this check box.SambaSamba is an implementation of Microsoft's proprietary SMB networking protocol. If you need toshare files, directories, or locally-connected printers with Microsoft Windows machines, select thischeck box.18.2.4. Other PortsThe Security Level Configuration Tool includes an Other ports section for specifying custom IPports as being trusted by iptables. For example, to allow IRC and Internet printing protocol (IPP) topass through the firewall, add the following to the Other ports section:194:tcp,631:tcp18.2.5. Saving the SettingsClick OK to save the changes and enable or disable the firewall. If Enable firewall was selected,the options selected are translated to iptables commands and written to the /etc/sysconfig/iptables file. The iptables service is also started so that the firewall is activated immediately aftersaving the selected options. If Disable firewall was selected, the /etc/sysconfig/iptables file isremoved and the iptables service is stopped immediately.The selected options are also written to the /etc/sysconfig/system-config-selinux file sothat the settings can be restored the next time the application is started. Do not edit this file by hand.Even though the firewall is activated immediately, the iptables service is not configured to startautomatically at boot time. Refer to Section 18.2.6, “Activating the IPTables Service” for moreinformation.18.2.6. Activating the IPTables ServiceThe firewall rules are only active if the iptables service is running. To manually start the service, usethe following command:[root@myServer ~] # service iptables restartTo ensure that iptables starts when the system is booted, use the following command:[root@myServer ~] # chkconfig --level 345 iptables onThe ipchains service is not included in Red Hat Enterprise Linux. However, if ipchains is installed(for example, an upgrade was performed and the system had ipchains previously installed),
