To start iptables on a Linux system, you will need to use the service command or the systemctl command, depending on your distribution.
For example, on most systems, you can start iptables by running the following command:
sudo service iptables start
On systems that use the systemctl command, you can start iptables by running the following command:
sudo systemctl start iptables
Note that starting iptables will not automatically apply any rules that you have configured. If you want to apply your iptables rules, you will need to run the iptables-restore command or the systemctl restart iptables command.