mjhjmtu

How do I disable the firewall in RHEL 6.8?
I tried

service iptables stop
chkconfig iptables off
service ip6tables stop
chkconfig iptables off

I can see that the service is off and disabled by running:

service iptables status
chkconfig --list iptables

The problem is that after I reboot the system iptables starts again. I grepped for "iptables" in /etc/init.d but did not find anything relevant.

I have access to both RHEL 6.9 systems and CentOS 6.9 systems and while both have internet access and while I don't want to boot them with the firewall turned off to test, have you tried running the system-config-firewall-tui command? Perhaps it does something slightly different than what chkconfig does (i.e. see /etc/sysconfig/system-config-firewall).

 $ sudo system-config-firewall-tui

It starts a console-gui that opens with an option to disable:

system-config-firewall

 ┌───────────┤ Firewall Configuration ├───────────┐
 │ │
 │ A firewall protects against unauthorized │
 │ network intrusions. Enabling a firewall blocks │
 │ all incoming connections. Disabling a firewall │
 │ allows all connections and is not recommended. │
 │ │
 │ Firewall: [*] Enabled │
 │ │
 │ ┌────┐ ┌───────────┐ ┌────────┐ │
 │ │ OK │ │ Customize │ │ Cancel │ │
 │ └────┘ └───────────┘ └────────┘ │
 │ │
 │ │
 └────────────────────────────────────────────────┘

Perhaps you should see if your system has this command and determine if it does what you desire.