Hi all,
I appreciate very much if anyone can help me or provide some comments.
I have a HTC TyTN. With this product, I can send UDP packets to a UDP server over the GPRS/3G network ( I downloaded a free trial IPer 6.0 product to generate UPD traffic. You can find the product at http://handheld.softpedia.com/get/Internet-Utilities/Testers/IPer-10064.shtml). This works when the Wifi is OFF. However, when the Wifi is ON, the UDP server cannot receive any data packets, even a single one.
So, my question is does anyone here experience the same problem before? If not, can anyone verify if your device behave similar to mine.
Thank you very much, and I am looking forward for your reply.
Sam
Related
I'm trying to VPN using GPRS to several networks which I have access to but I can't seem to be able to VPN them with my PDA2K. I can VPN them easily with no special configuration with my XP.
My i-mate keeps trying "Connectioning XX VPN..." and then aborts after about half a minute saying to check the username and password. The username and password are correct.
I called my cellular provider and they said that I should be able to connect to a VPN only if 'UDP Encapsulation' is defined on the VPN server?!?!? Well.. What is this thing? I'm trying to connect to big corp VPN, they wouldn't even listen to 'special requests'. I tried to connect to 4 different VPNs and I could not connect to any single one of them!
I really need that VPN connection via GPRS with my PDA2K. Any help would be more than appreciated. Maybe a different client than the built in VPN client of the WM2003SE ?
Thanks in advance.
Sorci
anyone?
bump for help. this gotta be a common prob.
Your GPRS connection will be subject to some form of NAT (Network Adress Translation) through your provider. VPNs don't get along well with NAT as the firewall doing the address translation modifies the packet header after it has had it's hash value calculated by the client (in this case your PDA). The receiving firewall will reject the packet as the hash values for the (now modified) packet don't match.
UDP encapsulation gets around this by encapsulating the encrypted and authenticated (secure) packet in a UDP packet which will be happily modified by the NAT'ing firewall. The receiving firewall will decapsulate(is that even a word?) the UDP packet and process secure packet inside as normal.
James
Thanks a lot Jamz for the thorough detailed info. I appreciate it.
So what's the fix? I tried several other VPNs and was unable to access them as well.. I can't just call all these providers and make some strange requests for a 'one guy with a pda2k and a gprs connection' that wants them to change their VPNs, enabling or disabling protocols or port.
Any other solution?
sorci said:
Any other solution?
Click to expand...
Click to collapse
Are you sure you're using the built-in VPN client in Windows, and not something like a Cisco VPN client?
You could try something like the Movian VPN client (not sure this is still made). I've used this previously with a Cisco VPN and it is fully configurable to handle multiple VPN types.
I've got a similar problem. Am trying to set up a temporary GPRS connection into my work LAN (I work for myself but 2nd child due shortly so want to be able to connect in from home for a couple of weeks only). I've got MS Win2000 Server set up to accept incoming VPN connections and it works fine on a dial-up connection but refuses to authenticate my username/pasword whenever I try to get the GPRS working.
As it's only going to be used for a short period of time, I'm loathe to spend out on any specific hardware/software but if anyone's got any suggestions, I'd be grateful.
If it helps, the LAN is behind a Netgear DG834GT ADSL modem/router/firewall and VPN PPTP and IPSEC are allowing in and out on it. The server is on a static IP address in the range 192.168.99.x.
GPRS Connections and VPN
With O2 you have to aks for VON connectivity to be enabled and connect to vpn.o2.co.uk instead of mobile.o2.co.uk. (by the way you can't access the web whilst connected to the vpn.o2.co.uk AP)
I suspect that most providers have simalair requirements
Dave
Hi all,
I'm brand new to mobile / pocket pc development, I just have a few networking related questios though.
I'm implementing my own blackberry style client/server for my brand new (got it yesterday) XDA IIi.
From what I've read the IP address of a mobile connected to GPRS will change every data session, so even though it has stayed 'online' all day it may have multiple IP addresses throughout the day. How do the blackberry style systems get around this? Is this todo with the IMS / SIP protocol ?
What I'm wanting is so that the mobile phone doesn't have to send any data to the server (apart from an initial hello) and then when mails come in the server can send directly to the mobile. Obviously with changing IP addresses this is impossible unless each time the IP changes the mobile tells the server, effectively you are not really pushing any more then it's more of a poll.
Also one more question on a non-development note, do providers charge for dropped packets or are they dropped normally before their routers so they simply never see them?
BTW I will be releasing the software I'm working on when done so don't fear
Thanks
bump ?
I guess not much known about GPRS / Blackberry workings ?
You can use WAP push to get in touch with the client on a Pocket PC Phone Edition. Have a look in the Phone API at msdn. I think you'll find something there...
Thanks! Totally forgot about checking MSDN ;P
This is possible, I do something similar. But it's difficult.
The IP assigned to your device is in private address space, using NAPT to contact Internet. Therefore you cannot contact the device IP in any way.
You can however open a connection from the XDA to any host on the Internet using TCP. Once this connection is open, it will remain open indefinitely. Or about 30 minutes if no data is transferred.
Once you have an open TCP connection, you can push data down the tunnel in either direction with very low latency. It is up to you to find a suitable protocol to run over your open tunnel.
Several things also need checking:
- Send some data every few minutes to keep connection open.
- Watch for stale GPRS connections. If this happens, remake the connection.
- Packets do get lost. Ensure all packets checked, resend if needed. You can use the TCP 'ACK' packet, or use your own acknowledgement protocol.
If you get it working, it works surprisingly well.
Hope this is of some use,
Ben Clewett.
HI there,
Has anyone experienced an issue whereby bluefire or similar contivity VPN client connects seamlessly over WIFI and 3G however will only allow RDP or VNC over WIFI.
I am currently running bluefire and am able to authenticate through 3G but thats it, I have no other functionality.
Any help would be great!
Thx
I've seen it where specific ports are blocked on the 3G providers network, but given that you're establishing a vpn tunnel, that should be irrelevent, as all the traffic should be tunneled via the VPN. I wonder if the Device isn't picking up the new route to send the traffic via the VPN, and is instead sending it via the 3g connection to a non-existant device.
Does your VPN-endpoint give you any logs to show if its actually receiving the traffic from the device? Are you able to ping anything within the remote network (assuming ping is allowed) from the device?
One thing I have noticed is that if you have a 3G connection open, then establish a wifi connection, the routing table doesn't seem to update to use the wifi connection and you actually have to kill the 3G session. I wonder if something like that is happening here - the 3g session establishes a default route, the VPN session then comes up but the device doesn't realise to send traffic via the VPN session. Or are you getting any traffic through the 3G/VPN connection?
I have the option to turn on verbose logging. I ll give that a go and see if it highlights anything really obvious.
MS Activesync (i'm using 4.5) does not support forwarding of UDP packets to the handset from the network. So far as I can tell it doesnt allow them to come out of the handset to the network either. When I say Network I mean IP Network, not Cellular.
Does anyone know of a way to add this feature to my setup, perhaps a UDP Proxy application that will puck up the packets on the ActiveSync Network adapter and forward them to the internet ? Or maybe something simpler like bypassing Activesync altogether ?
Hopeful,
nid
Are you trying to run any application specially using UDP's? I could access Internet once my ActiveSync is up.
Uh, yes, UDP is requred by the application I am trying to run.
http://forums.microsoft.com/MSDN/ShowPost.aspx?PostID=605596&SiteID=1
Hello everyone.
I am developing an application where I want a two-way communication between my cell phone (Nexus One, Samsung Fascinate both running Android 2.2) and my PC. Right now I am establishing a UDP connection between the phone and the PC and am able to communicate between the two over wifi. However, the communication fails when I am using 3G. I have tried it both ways - supplying the phone's IP address to the PC and vice versa but nothing works over 3G. I read somewhere that it could be due to NATs.
Has someone experienced this? How did you solve it?
Any pointers in the right direction would be much appreciated.
Thanks in advance.
For peer-to-peer communications, both (all) peers must "see" the other. That means that each peer must have an internet routable IP address. Otherwise, you need a centralized server that can bes "seen" on the internet that each peer connects to and the server brokers the connection between the peers. Of course, then it is no longer peer-to-peer.