Question

No Network Interfaces Bound to Firewalld Zone

Using a fresh build of CentOS 7.3, I am attempting to follow the tutorial at https://www.digitalocean.com/community/tutorials/how-to-set-up-a-firewall-using-firewalld-on-centos-7

However there are no active zones when I use “sudo firewall-cmd --get-active-zones” as per the tutorial. I believe this is due to no network interface being bound to a zone. Using comand “sudo firewall-cmd --zone=public --list-all public”. I can see that there are no interfaces bound to the public zone (which I presume is what I need). I have used:

  • $ sudo firewall-cmd --permanent --add-service=ssh
  • $ sudo firewall-cmd --permanent --add-service=http
  • $ sudo firewall-cmd --permanent --add-service=https
  • $ sudo firewall-cmd --permanent --add-port=80/tcp
  • $ sudo firewall-cmd --permanent --add-port=443/tcp
  • $ sudo firewall-cmd --reload

But I don’t think any of this is helping without an active zone. My goal is to have ports 80 and 443 show as opened after an external port scan, but they continue to show as closed. Please advise.

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To assign an interface to a zone, run:

  1. sudo firewall-cmd --zone=public --change-interface=eth0

Here is another useful command:

  1. sudo firewall-cmd --get-zone-of-interface=eth0

It allows you to find which zone to which a particular interface is bound.

I just build a Centos 7.5 system and my interfaces weren’t assigned to any zone. I added source ip ranges to trusted and created a few other zones with source ip ranges. All the zones plus the rules in the public zone are working.

I don’t know if it’s a bug or a feature, but not having to force an interface to a zone seems to be beneficial.