CentOS Firewall Administration | utility system-config-firewall

Preliminary preparation

Use the system-config-firewall tool, which will take the place of the present FirewallD, to configure the firewall on CentOS.

To do this, remove FirewallD from the OS autoload sector:

sudo systemctl stop firewalld.service

sudo systemctl disable firewalld.service

Now install the utility for further configuration:

sudo yum install system-config-firewall-tui

Firewall Configuration

After installation, run the initial setup:

sudo system-config-firewall-tui

A menu will appear on the screen to select further actions:

First, turn on the firewall mode, and then select the “Settings” item.

At the second step, we select from the list of services that are granted access to the external network:

In our example, we enable DNS and FTP. We press “Forward”.

The next paragraph suggests adding additional ports that are not standard:

The first point adds the port “from scratch”, i.e. The user sets the parameters himself. The second is for editing existing ones, and the third one removes the port from the list.

For example, let’s create port 8080 for the TCP protocol as follows:

The third step provides a list of network interfaces on the server platform. We mark only those items for which it is necessary to provide full access to the external network:

The NAT capability for network interfaces is provided via the following menu. It is referred to as “Masquerade” in CentOS. The thing that calls for this mode is marked as follows:

Now let’s set up port forwarding. The configuration is similar to the point with the addition of new ports.

Next is ICMP filtering. The default setting does not block traffic. If you want to disable, select the item:

The last step is to create the rules. We add our own templates according to which the firewall will process traffic:

Select item one to start a new one where we will set the requirements. The current template is editable as the second action, and the selected rule is deleted as the third action. To go back to the main menu, click Close.

Now select “OK” to activate the changes made. The utility will display a warning message. If everything is correct, then we agree:

Installation completed, firewall activated.

 

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