3CX: Configuring Ports on Your 3CX Server Using nftables

Step 1: Login to Your Server
First, you'll need to access your server via SSH.

ssh username@your_server_ip

Step 2: Open the nftables Configuration File

Once you're logged into your server, the next step is to edit the nftables configuration file. Run the following command to open the file in the vim editor:

vim /etc/nftables.conf

Step 3: Add Your Desired Port

In the vim editor, add the rule for your desired port. For example, to open port 8080 for TCP traffic, you would add the following line:

tcp dport 8080 accept

Or if you want to add multiple ports for TCP/UDP, you should add the following line: 

tcp dport {8080,8443} accept

udp dport {7000,150} accept

Ensure you place this line in the correct section of the configuration file, typically within the table and chain definitions for your firewall rules.

Step 4: Save the Configuration File

After adding your port rule, you need to save and close the vim editor. To do this, follow these steps:

1. Press Esc to exit insert mode.
2. Type :wq and press Enter to write the changes and quit the editor.

Step 5: Backup the Configuration File

Before applying the new configuration, it's a good practice to create a backup of the current configuration file. This ensures you can easily revert to the previous settings if something goes wrong. Run the following command to create a backup:

cp /etc/nftables.conf /etc/nftables.conf-BAK

Step 6: Apply the New Configuration

Finally, apply the new nftables configuration by running the following command:

sudo nft -f /etc/nftables.conf

This command loads the rules from the configuration file and applies them to your firewall.