Original address:

Execute in CentOS7

service iptables restart/start/stop

Error:

Redirecting to /bin/systemctl restart iptables.service
Failed to restart iptables.service: Unit not found.

The reason is because CentOS7 uses firewalld (please click for related introduction) to manage the firewall

Command syntax: firewall-cmd [--zone=zone] Action [--permanent]
Note: If you do not specify the --zone option, it is the default zone you are currently in, and the --permanent option is whether to write changes to the zone configuration file

The status of the firewall:
--state ##View the status of the firewall
--reload ##Reload the firewall, interrupt the user's connection, clear the temporary configuration, and load the permanent configuration in the configuration file
--complete-reload ##Reload the firewall without interrupting the user's connection (used when the firewall has a serious failure)
--panic-on ##Emergency mode, forcibly close all network connections, --panic-off is to close emergency mode

example:

Add port 80 as allowed:

firewall-cmd --zone=public --add-port=80/tcp --permanent (--permanent invalid after restart without this parameter)

Add range exception ports such as 5000-10000:

firewall-cmd --zone=public --add-port=5000-10000/tcp --permanent 

Effective immediately after adding:

Reload
firewall-cmd --reload
View
firewall-cmd --zone=public --query-port=80/tcp
delete
firewall-cmd --zone=public --remove-por=80/tcp --permanent

This is the problem I encountered when I just learned Linux to install tomcat under CentOS7 and cannot access the default page. Record it.

reference:

Centos7-----firewalld in detail>>>http://blog.51cto.com/11638832/2092203

Solve the problem of Unit iptables.service failed to load: No such file or directory. >>>https://blog.csdn.net/c233728461/article/details/52679558 (there is a restore traditional firewall under this link) Management method)