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UDP (incoming and outgoing) on GPRS

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Anonymous
June 21, 2004 3:30:00 PM

Archived from groups: alt.cellular.gsm (More info?)

I've been tasked with the development of our reporting client for mobile
phones/pdas. The idea is that the user submits a request for a short
report, the server then prepares the report (it can take a few minutes)
and then sends back the report to the client.
We need to use UDP for communications here. The use submits the request on
his phone/pda it is sent via the GPRS, as a UDP / datagram to the server).
The server determines the IP address of the phone/pda which originated the
request by looking at the source address in the datagram received. The
report is then prepared and sent to the requesting user/phone/pda.

I've been able to successfully receive UDP requests from the devices via
GPRS. Also the IP address can be determined.
However, when we send the short report, via UDP, to that IP address it
never reaches the phone/pda.

Anybody has any ideas?
Is it because O2 in UK (and may be other networks) block incoming UDP
traffic?
Is it because O2 use private IP addresses in their GRPS networks? IS this
true or do they allocate public IP addresses?

Any help or pointers will be greatly appreciated. Thanks.
Anonymous
June 21, 2004 4:39:05 PM

Archived from groups: alt.cellular.gsm (More info?)

Jonas Hei wrote:

[snipped]

> I've been able to successfully receive UDP requests from the devices
> via GPRS. Also the IP address can be determined.
> However, when we send the short report, via UDP, to that IP address it
> never reaches the phone/pda.
>
> Anybody has any ideas?
> Is it because O2 in UK (and may be other networks) block incoming UDP
> traffic?
> Is it because O2 use private IP addresses in their GRPS networks? IS
> this true or do they allocate public IP addresses?
>
> Any help or pointers will be greatly appreciated. Thanks.

I don't think every phone gets a public IP address but internal ones.
And the GPRS network is usually heavily protected by Firewalls and the
likes. One way might be to do the request via UDP and send the response
back via email?

Regards,

Marc
June 21, 2004 5:18:07 PM

Archived from groups: alt.cellular.gsm (More info?)

"Jonas Hei" <maps_263@hotmail.com> wrote in message news:<opr9xt0apfr0m89z@fx1025>...
> We need to use UDP for communications here. The use submits the request on

Why do you need to use UDP? I understand that UDP may be more
sensible, logically, but TCP should work for you, and it'll work on
all cellular networks.

> Is it because O2 use private IP addresses in their GRPS networks? IS this
> true or do they allocate public IP addresses?

Most networks use fake, aka private, IP addresses. Even when you get a
public address, chances are it'll still have the same restrictions. I
know that incoming TCP connections aren't allowed on T-Mobile US's
network.
Related resources
June 21, 2004 5:18:24 PM

Archived from groups: alt.cellular.gsm (More info?)

"Jonas Hei" <maps_263@hotmail.com> wrote in message news:<opr9xt0apfr0m89z@fx1025>...
> We need to use UDP for communications here. The use submits the request on

Why do you need to use UDP? I understand that UDP may be more
sensible, logically, but TCP should work for you, and it'll work on
all cellular networks.

> Is it because O2 use private IP addresses in their GRPS networks? IS this
> true or do they allocate public IP addresses?

Most networks use fake, aka private, IP addresses. Even when you get a
public address, chances are it'll still have the same restrictions. I
know that incoming TCP connections aren't allowed on T-Mobile US's
network even when you have a real, routeable IP address.
Anonymous
June 22, 2004 4:58:01 PM

Archived from groups: alt.cellular.gsm (More info?)

There are two options on the t-mobile GPRS plans; 'Internet' and
'VPN'. The internet plans give you a private 10.x IP address.

However, the VPN plan gives you a public IP address that does accept
incomming connection requests; at least for me.

-D

bb+graffiti.spam.gopi@andrew.cmu.edu (gopi) wrote in message news:<c060ee07.0406211218.25cce0f2@posting.google.com>...
> "Jonas Hei" <maps_263@hotmail.com> wrote in message news:<opr9xt0apfr0m89z@fx1025>...
> > We need to use UDP for communications here. The use submits the request on
>
> Why do you need to use UDP? I understand that UDP may be more
> sensible, logically, but TCP should work for you, and it'll work on
> all cellular networks.
>
> > Is it because O2 use private IP addresses in their GRPS networks? IS this
> > true or do they allocate public IP addresses?
>
> Most networks use fake, aka private, IP addresses. Even when you get a
> public address, chances are it'll still have the same restrictions. I
> know that incoming TCP connections aren't allowed on T-Mobile US's
> network.
June 23, 2004 4:01:47 PM

Archived from groups: alt.cellular.gsm (More info?)

dep_blueman@yahoo.com (dep_blueman) wrote in message news:<aa297123.0406221158.60d4d8de@posting.google.com>...
> There are two options on the t-mobile GPRS plans; 'Internet' and
> 'VPN'. The internet plans give you a private 10.x IP address.
>
> However, the VPN plan gives you a public IP address that does accept
> incomming connection requests; at least for me.

Really? I had the VPN plan and tested it 6 to 12 months ago and
incoming didn't work. Interestingly, if you used the WAP APN,
"wap.voicestream.com", devices can talk to each other. In other words,
you can telnet between various devices on the inside of their network.
O2 Germany, in my tests, hasn't allowed that.
Anonymous
June 25, 2004 11:08:51 PM

Archived from groups: alt.cellular.gsm (More info?)

I will try again using telnet for HTTP just for fun. It did work in
the Chicago market ~4 months ago when I first got the account but I
only tested it once to see what would happen.

....will post back with results.

-D

bb+graffiti.spam.gopi@andrew.cmu.edu (gopi) wrote in message news:<c060ee07.0406231101.30d197e2@posting.google.com>...
> dep_blueman@yahoo.com (dep_blueman) wrote in message news:<aa297123.0406221158.60d4d8de@posting.google.com>...
> > There are two options on the t-mobile GPRS plans; 'Internet' and
> > 'VPN'. The internet plans give you a private 10.x IP address.
> >
> > However, the VPN plan gives you a public IP address that does accept
> > incomming connection requests; at least for me.
>
> Really? I had the VPN plan and tested it 6 to 12 months ago and
> incoming didn't work. Interestingly, if you used the WAP APN,
> "wap.voicestream.com", devices can talk to each other. In other words,
> you can telnet between various devices on the inside of their network.
> O2 Germany, in my tests, hasn't allowed that.
Anonymous
June 25, 2004 11:25:08 PM

Archived from groups: alt.cellular.gsm (More info?)

Ok, either I was smoking something or something changed. I can't see
any incomming packets of any kind now with the VPN GRPS service.

-D

bb+graffiti.spam.gopi@andrew.cmu.edu (gopi) wrote in message news:<c060ee07.0406231101.30d197e2@posting.google.com>...
> dep_blueman@yahoo.com (dep_blueman) wrote in message news:<aa297123.0406221158.60d4d8de@posting.google.com>...
> > There are two options on the t-mobile GPRS plans; 'Internet' and
> > 'VPN'. The internet plans give you a private 10.x IP address.
> >
> > However, the VPN plan gives you a public IP address that does accept
> > incomming connection requests; at least for me.
>
> Really? I had the VPN plan and tested it 6 to 12 months ago and
> incoming didn't work. Interestingly, if you used the WAP APN,
> "wap.voicestream.com", devices can talk to each other. In other words,
> you can telnet between various devices on the inside of their network.
> O2 Germany, in my tests, hasn't allowed that.
!