firewall-cmd For hosts with firewall-cmd enabled (CentOS), you can use `firewall-cmd` command to allow traffic to specific ports. Use below commands to allow access to port 9000 ```sh firewall-cmd --get-active-zones ``` This command gets the active zone(s). Now, apply port rules to the relevant zones returned above. For example if the zone is `public`, use ```sh firewall-cmd --zone=public --add-port=9000/tcp --permanent ``` Note that `permanent` makes sure the rules are persistent across firewall start,...