How Do I Find Public Facing IP Addresses on a Firewall?by Jim Campbell
A public facing IP address is the address that identifies your network and allows you to connect to your network from the Internet. Before you can make this connection, you must know your public facing IP (Internet Protocol) address. You can use free websites to view the IP address from a computer on your internal network.
Click the Windows "Start" button and choose the shortcut that opens your preferred web browser. You can use any web browser to view the IP address. If you are unsure if you have a third party browser, type "internet explorer" in the search text box and press "Enter."
Navigate to the home page for any website that displays your IP address. Each website displays an IP address on the home page.
Review the IP address displayed. This is your public facing IP address used to access your internal network from the Internet. You can also send this IP address to other users who need to connect to your network.