Question : I set up my firewall/packet filtering but after a reboot the rules are not there any more.
By default, rules created with the iptables command are stored in memory. If the system is restarted before saving the iptables rule set, all rules will be lost. For netfilter rules to persist through system reboot, they need to be saved. To do this, log in as root and type:
# service iptables save
This executes the iptables init script, which runs the 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 iptables-restore command.
Another method to save the iptables rules
Another option is to use the iptables-save and iptables-restore commands. To save the current iptables rule set into a file of your choice :
# iptables-save > /tmp/rules.backup
Restoring the Rules
You can restore the ruleset at a later time by running
# iptables-restore < /tmp/rules.backup
Ensuring that iptables service start on boot
Another issue commonly faced by users is that the iptables service in not enabled to start on boot. To avoid this, verify that the service was set to start on boot
# chkconfig iptables --list iptables 0:off 1:off 2:off 3:on 4:on 5:on 6:off
If iptables is off, then enable the service for runlevels 3-5
# chkconfig iptables on