Does iptables -F permanently delete all iptables rules?

Question

In a RHEL training document, the author says:

...run the following command to disable the firewall on the current system: iptables -F

He explicitly uses the word "disable" which to me suggests that it will be simple to re-enable. In reading the man page though for iptables, I see this:

Flush the selected chain (all the chains in the table if none is given). This is equivalent to deleting all the rules one by one.

Can I get clarification on the expected behavior?

Answer 1

The iptables rules are stored in two places on Red Hat systems:

• In memory within the running kernel, where the firewall code checks them on network I/O. Flushing the rules with iptables -F gets rid of this ruleset only.

• In /etc/sysconfig/iptables from which they are loaded on boot. You can force a reload without rebooting with service iptables reload or ...restart.

So the answer is no, flushing the rules with iptables -F is not permanent.

When you go into setup and modify the firewall rules, it saves them in /etc/sysconfig/iptables. You're not supposed to edit that file directly, but if you know the iptables command line format, you can pretty easily figure out the format of this file.

Answer 2

Also, as a point of reference, here's how to flush ALL the current iptables rules:

#!/bin/sh
echo "Stopping firewall and allowing everyone..."
iptables=/sbin/iptables
$iptables -F
$iptables -X
$iptables -t nat -F
$iptables -t nat -X
$iptables -t mangle -F
$iptables -t mangle -X
$iptables -P INPUT ACCEPT
$iptables -P FORWARD ACCEPT
$iptables -P OUTPUT ACCEPT