How to save iptables settings once and for all?

Question

CentOS

Centos 7
I tried different methods that are offered on the Internet, however, after restarting the system, the iptables settings are reset.
What method are you using? Centos is fresh.

Answer 1

On Centos 7, firewall-cmd is preinstalled. If you haven't removed it, then you should use it.
Adding port 80:

firewall-cmd --zone=public --add-port=80/tcp --permanent
firewall-cmd --reload

Then you can check. Whether the port is added to the rules:
You can delete the rule as follows

firewall-cmd --zone=public --remove-port=80/tcp --permanent
firewall-cmd --reload

Check:
Should be empty.
I was directed to this option by Roman Sokolov
Thanks to him for this.

Answer 2

service iptables save
service iptables restore
well, read the documentation...

Answer 3

yum install iptables-services
iptables -F
iptables-save | sudo tee /etc/sysconfig/iptables
All rules, for example:
iptables -A INPUT -p tcp --tcp-flags ALL NONE -j DROP
...
iptables -L -n
iptables-save | sudo tee /etc/sysconfig/iptables
service iptables restart