After reading my article on stolen IP addresses, Natalya Kuznet asked if someone could steal your mobile IP address.
I very much doubt that anyone would even try to steal your mobile IP address, for the simple reason that it isn’t worth stealing. There are other reasons to be careful about your mobile IP address, though.
First, let’s understand the basics. Every device on the Internet has two IP addresses: a public and a private one. In your home, your router uses your public IP address—assigned by your ISP—to connect to the Internet. Your router assigns private IP addresses to PCs and other devices to create a local network. Only the public address is visible outside of your network, and only it can be linked to your home.
Your mobile devices also have public and private IP addresses. But they’re constantly changing, and therefore, pretty much meaningless.
[Have a tech question? Ask PCWorld Contributing Editor Lincoln Spector. Send your query to firstname.lastname@example.org.]
The exception is when you’re connecting your mobile device through Wi-Fi rather than a cell network. In that situation, neither your router nor the Internet cares whether it’s a smartphone or a desktop computer. If it's your home Wi-FI, my previous advice applies. If it's public Wi-Fi, follow this advice instead.
When you use your carrier’s network, however, you’re using your carrier’s IP addresses, and they’re changing all of the time. Your private address connects you to the nearest cell tower. Your public address is one of many that connects your carrier’s network to the Internet. I checked my public IP address several times as I moved around town, and I never got the same number twice—even when I revisited a location where I’d checked it before.
In the extremely unlikely event that an IP address were stolen, it wouldn’t be your problem. It would your carrier's problem.
By the way, in my tests I discovered that Verizon’s 4G network uses IPv6 for its public and private addresses. It’s nice to know they’re not going to run out of numbers.
But don’t relax too much. Your carrier knows what IP address you were using at any given time. It also knows where you have been. Neither you nor I truly know what it does with that information, nor how well it protects it.
Keep that in mind when you use your phone.