I have set up a Centos 7 server to run Nagios. By default the OS has pretty draconian iptables rules and a fellow here suggested fixing this by inputing this command:

```
iptables -A IN_public_allow -p tcp --dport 80 -j ACCEPT 

```

This works fine until I restart the server, at which point I have to input the command again, otherwise the server is unreachable once again.

Is this normal behaviour for iptables? Can I do something to fix it?