2.8.9.3. Saving IPTables Rules

Rules created with the iptables command are stored in memory. If the system is restarted before saving the iptables rule set, all rules are lost. For netfilter rules to persist through a system reboot, they need to be saved. To save netfilter rules, type the following command as root:
~]# /sbin/service iptables save
iptables: Saving firewall rules to /etc/sysconfig/iptables:[  OK  ]
This executes the iptables init script, which runs the /sbin/iptables-save program and writes the current iptables configuration to /etc/sysconfig/iptables. The existing /etc/sysconfig/iptables file is saved as /etc/sysconfig/iptables.save.
The next time the system boots, the iptables init script reapplies the rules saved in /etc/sysconfig/iptables by using the /sbin/iptables-restore command.
While it is always a good idea to test a new iptables rule before committing it to the /etc/sysconfig/iptables file, it is possible to copy iptables rules into this file from another system's version of this file. This provides a quick way to distribute sets of iptables rules to multiple machines.
You can also save the iptables rules to a separate file for distribution, backup, or other purposes. To do so, run the following command as root:
iptables-save > <filename>
… where <filename> is a user-defined name for your ruleset.

Important

If distributing the /etc/sysconfig/iptables file to other machines, type /sbin/service iptables reload or /sbin/service iptables restart for the new rules to take effect. It is better to use the reload command because there is no period of time without a firewall in place. See the description of the reload command in Section 2.8.9.4, “IPTables Control Scripts”. For IPv6, substitute ip6tables for iptables in the /sbin/service commands listed in this section. For more information about IPv6 and netfilter, see Section 2.8.9.6, “IPTables and IPv6”.

Note

Note the difference between the iptables command (/sbin/iptables), which is used to manipulate the tables and chains that constitute the iptables functionality, and the iptables service (/sbin/service iptables), which is used to enable and disable the iptables service itself.