For iptables on CentOS there is an additional location which is where I have those particular modules configured to load and that's the
/etc/sysconfig/iptables-config file. The start of the file looks like this
# Load additional iptables modules (nat helpers)
# Default: -none-
# Space separated list of nat helpers (e.g. 'ip_nat_ftp ip_nat_irc'), which
# are loaded after the firewall rules are applied. Options for the helpers are
# stored in /etc/modprobe.conf.
When I run
service iptables restart I get this line
Loading additional iptables modules: nf_conntrack_ftp nf_co[ OK ]
If I play with the contents of the
above it changes the output of the
Loading additional modules line when I restart the service.