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December 9, 2008 9:48 PM

GPRS / local IP networking problem.

I hope someone can suggest a possible solution to the following problem.

We have a remote computer system (a linux box, I can find more details if required) which we need to connect to in order to update some files perioically. This remote computer has no internet connection available as such, however we hoped to connect to it using a GPRS modem.

The problem is that when we connect from our home location, our traffic (with our known static IP) is routed through a GPRS server which then connects us to the target computer with a local IP address. I understand this means that we cannot authenticate on the target computer. Is there some way around this problem? I do not think it is possible to get a public IP address. All suggestions are welcome, as our current proposed solution send the updated files by physical mail.

Apologies if this description is unclear in any way; I am not the person carrying out this work but of course I will try to add any extra information.
Thanks.

posted by theyexpectresults to computers & internet (3 comments total)

Hamachi sounds like what you need. :)
posted by TheNewWazoo at 10:58 PM on December 9, 2008

You mean you are able to connect to the remote (GPRS) machine from your fixed-IP-address machine? I would have expected that to be your problem— my experience of GPRS has been that the gprs-connected machine gets assigned a temporary IP and is probably behind a NAT run by the cell provider.

If you can actually establish a connection and your problem is merely how to authenticate that this random incoming connection is from who you think it is, I suggest using ssh, with either public-key authentication or host-based-public-key authentication (basically the same thing, but authenticating the connecting user or the connecting host, respectively). It might be easiest to ssh in and then use port forwarding to run whatever protocol you were already using.
posted by hattifattener at 11:02 PM on December 9, 2008

Thanks for the help. We are now thinking of having the GPRS machine announce it's address periodically to get around part of the connection problem. Will see how it goes.
posted by theyexpectresults at 4:53 PM on December 11, 2008