NAT

At home, the router gives your laptop, phone and TV internal addresses like 192.168.0.10. They all go online through the router's single external address, and NAT remembers which device to return each response to.

That is why the address in your phone's settings and the address websites see are almost always different. The My IP page shows the external address.

When a carrier applies the same principle to thousands of subscribers at once, it is called CGNAT. Most mobile networks work this way.

NAT does not hide you from a website: the site sees your network's external address and uses it to determine the country and ISP. For a site to see a different address, you need a proxy.

How to see NAT on your own network

Look up your computer's local address: on Windows with the ipconfig command, on macOS and Linux with ifconfig or ip addr. You will see something like 192.168.0.10. Then open the My IP page without a proxy: it shows the external address, the ISP and an approximate city.

The third point is the WAN address in your router settings. If it matches the one on the page, you have a single NAT, the home one. If the router shows a private address, the ISP adds one more layer, and that is CGNAT.

NAT and the IP whitelist

The Prokso IP whitelist sees only the external address. So when you add your home address, you open the plan to every device behind that router: the laptop, the phone, a second computer. In an office the same applies to all colleagues who go online through one address.

If your ISP assigns a dynamic address, it may change after a router restart. The program then gets an authorization error, and you have to update the address in the whitelist. When this happens often, it is more convenient to switch to a username and password.

What NAT does not do

• It does not change the time zone, the browser language or the User-Agent: the site sees them as they are.
• It does not give you another country: the external address belongs to your ISP.
• It does not let incoming connections through without separately configured port forwarding.

For a website to see a different address you need a proxy, and the same My IP page is the place to check it. If it shows the same address with the proxy as without it, the program bypasses the proxy, and its settings need a closer look.