Rules disappear after restarting iptables

Created:

2017-06-05 05:07:59 UTC

Modified:

2017-07-04 08:49:38 UTC

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Rules disappear after restarting iptables

Applicable to:

  • Plesk for Linux/Unix
  • Plesk Sitebuilder for Linux/Unix
  • Plesk Expand
  • Virtuozzo containers for Linux
  • Virtuozzo hypervisor
  • Operations Automation
  • Business Automation
  • Odin Business Automation Standard

Symptoms

I have stopped and started iptables with these commands:

# /etc/init.d/iptables stop
...
# /etc/init.d/iptables start

Now I see that some rules have disappeared. What could be the reason?

Cause

If rules were added using /sbin/iptables utility, they were added to a chain in the memory and were not committed to the hard disk. Upon restart, those rules were flushed from the memory and not restored.

Resolution

In order to avoid losing rules during an iptables restart, you need to save them before the restart.

Method 1:
# iptables-save > iptables_save.txt

If using this method, you will need to restore the rules after the restart:
# iptables-restore <iptables_save.txt


Method 2:
# /etc/init.d/iptables save
Saving firewall rules to /etc/sysconfig/iptables: [ OK ]

The above command saves the rules to the file system, and an iptables restart will not affect them.
This method is preferable if you want to leave the server intact.
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