If you're unable to access your server via SSH because of a rule added to iptables in error, it is simple to flush iptables so that you can regain access if cPanel is installed on your server.
All you need to do is append the following to your WHM URL and then log in using your root login details when prompted:
/scripts2/doautofixer?autofix=iptablesflush
For example, if your server IP is 192.168.1.100, then you would use this URL:
https://192.168.1.100:2087/scripts2/doautofixer?autofix=iptablesflush