My Pi 2 is logging temperature and humidity, and is connected to a PiNoir Camera. The Pi 2 is connected to the internet via a 3G USB Modem.

I'd like to view my logged data (RRDtool Database) and a webcam picture from a browser.

I tried lighttpd but never got it to work. Although the server was running I was never able to actually connect to the IP address from the Pi 2.

I think it is because my provider simply does not allow this form of communication.

Is there any other way I can do what I want (without extra costs) or are those the simple limitations of a 3G connection and I've got to deal with it?

My current setup sends me everything via mail whenever I send a request and I can live with that but I'd like to know if I might be missing a cool option here.

P.S.: I know that the connection would be really slow but as I mentioned, it's only to look at some RRDTool graphs and watch a webcam picture from time to time.

Edit: Well I I read in a couple of Boards that a lot of Provider use a carried grade NAT which kinda blocks inbound connections ... :-( when running sudo ip addr show i get

inet 10.XX.XXX.XX peer 10.XX.XX.XX/XX scope global ppp0

I'm not a network guy.... but I think there should be only one IP address for what I want to do with the connection...

Thanks for the help so far

I think, that there's something provider wise prohibiting me from getting the server to work when on 3G. I tried everything within my wlan and it worked for example: with hostname -I I get a normal looking 10.XX....IP but i can`t ping it from another pc ...

Guess I have to call my provider directly to figure out if what I want to do is doable

  • As far as I'm aware, my 3G provider here in the UK doesn't block any traffic. There's nothing inherent to 3G that would stop someone from accessing a server. I would try setting up lighttpd using a local network connection (not 3G) and make sure everything's working as it should be. If that works on a local network but fails on 3G then at least you know 100% where the problem is.
    – goobering
    Apr 28, 2016 at 14:54

2 Answers 2


The problem is not that you've got a dynamic IP but NAT .

You need to use reverse SSH tunneling , OpenVPN in client mode or some SaaS service like Weaved , yaler or ngrok.

  • ok thanks, that did not come to my mind. I am using weaved for ssh stuff on this pi .... I'm going to look into that
    – Peter S
    May 2, 2016 at 9:11

I think there should be only one IP address for what I want to do with the connection

That's not how mobile networking works. You cannot have a static stable IP for incoming connections. This is not the same as your provider actively preventing anything, it is simply a limitation of the context. The fact that the unit is not truly "mobile" doesn't make much difference.

You could route through a server with a stable address or domain (a domain can resolve to a dynamic IP). There are paid and unpaid services for the latter; I think the best known is "no-ip".

  • I though the IP changes when logging off and on again but once I have an ip I could use it to access the server. For using it regular I was going to look for a dynamic ip service
    – Peter S
    Apr 28, 2016 at 16:08
  • I just read a textbook on this last year and I've already forgotten the details :/ but I believe the deal with 2/3/4 G mobile is that you're basically on a kind of WAN (wide area network) where you have a stable address within that, but traffic is routed to you the same as your computer at home is routed to within the LAN there. If you look at your computer's address, it's an obvious LAN address (e.g That's not what the outside world sees. It's what the router sees, and the world sees the router.
    – goldilocks
    Apr 29, 2016 at 12:13
  • Messages that go back and forth have the address translated by the router, which keeps the LAN sorted based on MAC address. Mobile is similar in that cell towers are like access points, not routers -- the routing is done by other nodes that are part of the service providers network. I could be wrong about the details here and am too lazy to go jog my memory at wikipedia (or dig through the textbook again...) but point being, there is a similar problem with mobile devices as there is with home networked devices regarding an address at which you could be contacted unsolicited.
    – goldilocks
    Apr 29, 2016 at 12:14

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