What NAT do I see on my internet connection?
What NAT do I see on my internet connection?
Hello, there is a free NAT test at https://tomchen.github.io/symmetric-nat-test/. It shows normal NAT in my case. My internet provider gives me a public IP address. So does that mean it tells what kind of router I'm using? If I had a private IP instead, say if my ISP gave me an internal number and then put all my devices behind their own router... would this test show the type of NAT the ISP's router has or will it still tell me about my own router? I am pretty confused how this thing actually works. Thanks
Yes, your router has a special kind of NAT that comes built-in. Just like most internet companies give you one public address to show people on the outside world, but only have access to a private address inside your house, you probably already have this set up. Usually, these private addresses are assigned by the local server or router automatically using DHCP unless you manually set them to be static. You can change that NAT type yourself if you want to go into your router's settings panel.
Have no idea why that tool calls "normal." Most consumer routers already have this built in because they are symmetric, so isn't that standard? In any case, if your ISP uses NAT, you now have two NAT routers in the way. So whatever that word means could be different on each router depending on what it checks. I guess what it is testing for matters a lot here but I would bet it won't work with 2 or more NAT routers in the path. It really doesn't matter since almost every consumer router does this by default and you can't run anything else. A lot of the other stuff some other forms of NAT do is done through UPnP on consumer routers if the app supports it.
Thanks for sharing your answers. It seems like I figured out who that developer was trying to fix. They made an online multiplayer game and ran into a problem: they can't connect two players on the internet when both are behind a symmetric NAT (also called "Bad NAT"). That user said this stops gaming, while normal means asymmetric NAT. The report says my case has symmetric NAT. I'm stuck here though. What does that network actually see? Is it my router or the ISP's equipment if there is one?
There are many ways two people can play games while both inside a home network called NAT. They often need to set up things like port forwarding or UPnP to fix the problem. If you used some other app that didn't use those tricks, it wouldn't work either. Apps like VoIP have ports changing all the time, so that's not what most people worry about. If you have a public IP, there are ways to bypass rules like this. It is when people don't have one and their ISP handles the NAT stuff then big problems happen. Since you can't change your internet company's gear, you can't set up port forwarding or do anything similar. I don't know exactly what kind of tool they're testing here for.
I am not entirely sure about this question, but technically NAT looks at all things. It catches packets going toward your public IP and changes them to the right private IP. This lets you have more than one device use the internet on just one router. NAT saves your private IP in a list so when you send or get data from the web, it routes through your internal private IP using that saved info. NAT mostly fixes the problem of having only about 4 billion IPv4 addresses. It's basically one big translator between the public web and your local network.
I probably can't say exactly why because I don't know enough. If I tell you that "my device and the internet are behind a symmetric connection," does that mean we're using symmetric NAT from my machine to the outside world? It might be that my router uses Cone-NAT while your ISP's gateway uses Symmetric NAT. If that is true, what kind of NAT applies to me? I'm sorry if I am being unclear. Thanks for reading!
The actual NAT thing doesn't really matter if those IP addresses are public or private, mostly because of where the source port numbers get put into that NAT table. Your IP address always gets translated to whatever IP is on the WAN side of your router, no matter if it's a public or private one. Whether you use a specific type of NAT on your own router while another router from your ISP runs NAT in front of yours doesn't make any difference anyway. The ISP will usually run something called symmetric NAT. This setup generally stops any incoming sessions from being started.