How do IP addresses work?

Question

I kinda get how it makes sense on a local network, because it’s kinda like a list of the devices that are connected to it and your trying to communicate with other machines connected together in that same list. But this feels like a really surface level understanding and I don’t know what I’m missing.

I understand that they’re a string of 4 digits from 1-255, such as 192.168.1.1 being really common for home networks. But I don’t know what the numbers each mean. I think 192 in this case is a reserved value for home use? Same with 10? And the last number is basically the number of the device on the network I think. But I don’t understand the numbers for x.168.1.x

What I really don’t understand is how public IPs work. You hear online about not leaking or sharing your public IP or it can be used to find (pretty close to) where you live. How? How are they assigned to the billions of connected devices in the world?

I’ve been watching videos about trying to set up a FOSS router because it’s really interesting, but IPs seem like dark magic to me

In: Technology

Answer 1

It’s an identifier. Just like your phone number. If someone knows your phone number, they can call you. And with the access to proper information, they can tell where you are (much easier back in the day of landlines). If someone knows your IP address, they can send things to you. And with access to the proper information, they can tell where you are.

Now access to that information typically means phone company or ISP records. So unless they know someone or have a court order, that shouldn’t happen.

And in the case of the general public using the internet, you’re probably getting an IP address through DHCP. Which means you don’t have a permanent IP address. It’s a dynamic address and could be changing daily. So if they know your IP address today, that may not be useful tomorrow.

As for how the addresses are assigned to billions of people, there are about 3 billion possible public IPv4 addresses. That’s not nearly enough for all the devices in the world. So for most people with residential service (and many businesses), a function known as NAT (Network Address Translation) is used. This allows all the different devices in your home to use the single public IP address that your home is using.