One-to-One NAT

This type of NAT maps one internal IP address to a single external IP address. In this case, the internal machine (IM) will have a private IP, and it will be mapped to a public IP address provided by the BFL (Broadband Service Provider or similar entity). This means any traffic destined for the external IP will be forwarded to the internal machine's IP, and the responses will follow the reverse path.

This is commonly used for servers or devices (like web servers, mail servers, or VPN appliances) that need to be accessible from the internet, but you want to maintain the security of a private IP for internal communications.

The exact steps depend on the specific router, firewall, or NAT device you're using, but here's a general outline of what needs to be done:

Step 1: Access the NAT Configuration Interface

• Log into the router or firewall device that handles the public IP and internal network.

Step 2: Configure the One-to-One NAT (Static NAT) Rule

• Locate the NAT Configuration or Port Forwarding section in the firewall/router interface.

• Create a new One-to-One NAT or Static NAT rule.

  • Internal IP: Specify the internal machine's IP address (e.g., 192.168.1.10).
  • External/Public IP: Specify the BFL-provided public IP address (e.g., 203.0.113.10).

  The rule will look something like this:

  • Source IP: Any (meaning traffic from any external source).
  • Destination IP: The BFL-provided public IP (203.0.113.10).
  • Mapped IP: The internal machine's IP (192.168.1.10).

Step 3: Define the Port Range (If Necessary)

• If only specific ports need to be mapped (e.g., port 80 for HTTP, port 443 for HTTPS, etc.), define the port range.
  • For example, if the internal machine hosts a web server, you would map external port 80 (HTTP) or 443 (HTTPS) to the internal machine's corresponding port.

Step 4: Save and Apply the Configuration

• Once the NAT rule is set up, save the configuration and apply it.
• The device will now forward incoming traffic on the external IP to the internal machine.

Step 5: Test the Configuration

• From an external network, test the configuration by accessing the public IP (203.0.113.10).
• You can do this by using a browser (if it's a web server) or by using tools like ping, telnet, or curl to test connectivity.