dynamic DNS for 3G USB modem raspberry pi

Your provider (in this case the 3G one) will assign you an IP address. When your location is static, say on a cable or ADSL connection, they may decide to give you the same IP address every time your computer/modem starts up. But they could also decide: we need less IP addresses because half the people have their modem turned off. So then they have to cycle through the IP addresses to serivice those that are online.

Anyway, with 3G, you are likely to get a new/changing IP address every time your connection starts up. Or maybe even when you switch towers (but I doubt that:  they should make arrangements to fix that if it happens).

Anyway, if you install something like "dyndns", you will be able to refer to the 'pi as <something>.dyndns.org, which will resolve to whatever IP address you got this time.

However, I've also seen 3G providers that use "internal" IP addresses on their network. In that case instead of assigning an externally visible IP address to every "phone", they use an "internal only" IP address range, that only works within their own network. And when packets from your 'pi go out on the internet they are quickly translated to some public IP address. Return traffic is similarly modified to go back to your phone. This way they can save enormously on the number of public IP addresses that they need. But it means you cannot reach the internal IP addresses at all from the outside. (which is usually a bonus, because it prevents remote network attacks!).

So, if you do a quick "ifconfig" and show us the results we can look up if your 3G modem gets a public IP address.

Thank you for your reply .

rew

When I do ifconfig on the pi, the Ip address I get is something like 192.168.0.100, which is an internal address I guess. Will dydns still work ?

What I am trying to do is use motion camera software on the pi to broadcast a video stream onto a certain IP address and port number.

I want to be able to use the same Ip address every-time (reboot, new connection, etc).

Yup! That's an internal address which is not reachable from the outside.

I personally own a "server" on the internet. For cases like this I will have the 'pi call out to the server which is similar to loading a website. Thus the provider will have to make that "work", otherwise nobody would be able to use the internet.

Then I create a "tunnel", so that from the server I can reach the 'pi. Next some trickery with ports and stuff and I'd be able to reach the 'pi from around the globe.

If you don't have your own server, I'm not sure if you'd be able to find a low-cost provider for such a service. I've searched for "free tunnel service" for a few minutes now, and the services that come up do something close to the reverse of what you want.... :-(

Yup! That's an internal address which is not reachable from the outside.

I personally own a "server" on the internet. For cases like this I will have the 'pi call out to the server which is similar to loading a website. Thus the provider will have to make that "work", otherwise nobody would be able to use the internet.

Then I create a "tunnel", so that from the server I can reach the 'pi. Next some trickery with ports and stuff and I'd be able to reach the 'pi from around the globe.

If you don't have your own server, I'm not sure if you'd be able to find a low-cost provider for such a service. I've searched for "free tunnel service" for a few minutes now, and the services that come up do something close to the reverse of what you want.... :-(