Using System.Net.Socket over gprs..

  • Thread starter Thread starter chris-s
  • Start date Start date
C

chris-s

Hi folks,

Experimenting with the idea of using system.net.sockets for some very
simple 'push-messaging' over GPRS where the server/listener is running
the mobile device and the client runs on a PC.

I'm more than aware of all the issues surrounding change of
ipaddress/availability etc relating to a mobile device connecting via
GPRS. Right now, the device is connected and whilst testing it's
ipaddress does not change or loose it's connection, unless there is
something more subtle going on, the basic connection does not appear to
be a problem.

A very simple client/server app runs fine when the device is on the
local network, but the client fails to connect to the mobile server
when the server is connected with GPRS. However, switching the apps
around and running the server on the PC and the client on the GPRS
device works fine.

It is almost like the provider is port blocking the incoming connection
to the mobile device but allowing the outgoing connection (it's not a
local firewall/router issue). Does this sound plausible, I'm using
Orange in the UK (APN: orangeinternet)?

I have also tried running an FTP server on the device, this works fine
normally, but when trying to connect to it over the GPRS, it fails, as
does trying to ping the device.

Cheers

Chris
 
Running servers on the device is probably blocked by your GPRS network
provider. There's nothing native to the network stack, at least, that would
prevent you from running a server on the device and connecting to it from
your Internet-connected PC, provided that you have the IP address, of
course.

Paul T.
 
Hi Chris,
there could be a problem with the IP address of your device. Normally your
device will get a private IP address in the network of your provider (starts
with 10.x.y.z). You can't ping this IP address from your PC, because the
provider does some NAT (Network address translation). In the other direction
you can ping your PC, because he should have an public IP.
In your private network everything works fine, because the IP-addresses are
public to the other.
In my opinion this behaivor also depends on your provider or the contract.
With Deutsche Telecom we had a SIM card for the mobile, where the IP address
of the GPRS connection was public, with Vodafone not.
Now I've no experiences, how this could influence your client/server app.
Steffen N.
 
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