Solved

Title: Listening to UDP port

Posted on 2006-06-24
6
1,298 Views
Last Modified: 2008-03-10

Hi,
  I am doing a GPS application using Vb.net (Windows application).
The application is  listening to a UDP port where the GPS data is coming.
The test GPS unit is reporting to the server and I am able to identify the IP of GPS unit thru my  program  . But the actual data send from the gps unit is not available in my receiving application  . Instead, whenever some data comes , I see only 8 byte long junk characters in my application.
     (Strangely, if I run another application developed to recieve the GPS data exactly the same way from the same port - After that when I start my application I get all the GPS Data  and the 8 byte junk data.)
 
  Someone say something to be done with the socket layer.


Can you help me ?

   Sam
0
Comment
Question by:sgs1970
  • 4
  • 2
6 Comments
 
LVL 5

Expert Comment

by:vilia
ID: 16986094
What is the data format the GPS sends (NMEA or a proprietary format)? If it is NMEA you should receive a few packets every second.

NMEA sends sequences of alphanum data plus comma and CR/LF. Proprietary protocols usually use binary data. Did you try to hex dump incoming data?
 
What is the GPS model that you use?


0
 

Author Comment

by:sgs1970
ID: 16993259

Hi vilia ,
 I use intellitac X8 gps  units .  It may be a   proprietary format (my assumption) .
  I know only to hexdump a file .
   

    thanking you,
              samson
0
 
LVL 5

Expert Comment

by:vilia
ID: 17006139
Samson,

the very frst thing you should look for is the technical documentation that describes GPRS UDP/TCP communication.

I have looked at:
http://www.systech.com.tw
pdf files:
Program Manual for InstallWizard-130        
Program Manual for Tracer-1.30

It looks X8 sends additional data in additon to GPS data on UDP/TCP.

If you do not find documentation, and you like hacking, you need to monitor comunication between the X8 and the Working program you have mentioned. It could be done by network/packet sniffing or puting a proxy between the X8 and the program.

Vilia
0
What Security Threats Are You Missing?

Enhance your security with threat intelligence from the web. Get trending threat insights on hackers, exploits, and suspicious IP addresses delivered to your inbox with our free Cyber Daily.

 

Author Comment

by:sgs1970
ID: 17067306

 Hi,
   Sorry for the delay as this is like a research  project  .

  I sniffed the port  . It seems like the GPS data is blocked to get into the port when my application runs .(Trying to receive but fails) . When the other application runs this blocking is someway removed and data is made available. This appears to me like people waiting for a free show. Until the guard opens the door, people need to wait.

    How do I get the key for this free show?

   Sam
0
 
LVL 5

Expert Comment

by:vilia
ID: 17081258
Hi Sam,

The "blocking" you are tolking about is some kind of the communication protocol, probably.

In order to capture one you need a sniffer. You can use FramePad for example:
http://www.beesync.com/downloads.html
the one has a free trial period.

- Start FramePad and put IP filter both for Tx and Rx packets on the IP address of the GPS.
- Turn on GPS
- Start Application
(try different startup sequence as well)

You would see UDP packets. Look for the UDP port of the GPS (in the packets Application sends to the GPS). It coul be different then the Aplication UDP port. (UDP headers).

Analyze timing and data. Who sends what and when. (data portion of UDP packets).

If you can't decode portion or all of captured data. Try simply to send the same data from your application in the same sequence as the Working Appication does. (monitor correctness of the communication with sniffer).

Vilia
0
 
LVL 5

Accepted Solution

by:
vilia earned 250 total points
ID: 17090673
Hi Sam,

I have found the protocol document:
http://perso.orange.fr/nomadicsolutions/doc%20syntaxe/IntelliTrac%20X%20Series%20Protocol_TA%20_1st%20draft.pdf

This should be the last nail.

Vilia
0

Featured Post

How your wiki can always stay up-to-date

Quip doubles as a “living” wiki and a project management tool that evolves with your organization. As you finish projects in Quip, the work remains, easily accessible to all team members, new and old.
- Increase transparency
- Onboard new hires faster
- Access from mobile/offline

Join & Write a Comment

Suggested Solutions

Title # Comments Views Activity
Google Maps 4 414
Mobile Phone Proximity Marketing 6 1,096
Google Maps - InfoWindow 3 744
GPS with route remote planning 1 88
I feel like more and more people want to know how to programmatically convert addresses into geospatial locations. So in this article, I will show you how you can do it with Bing Maps. I'm going to use PowerShell, which is a nice scripting language,…
Introduction This article is designed to assist GIS (Geographic Information System) and GPS (Global Positioning System) developers using ESRI ArcGIS and other spatial information management systems.   For the uninitiated the concept of projectio…
This tutorial demonstrates how to identify and create boundary or building outlines in Google Maps. In this example, I outline the boundaries of an enclosed skatepark within a community park.  Login to your Google Account, then  Google for "Google M…
This tutorial walks through the best practices in adding a local business to Google Maps including how to properly search for duplicates, marker placement, and inputing business details. Login to your Google Account, then search for "Google Mapmaker…

708 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question

Need Help in Real-Time?

Connect with top rated Experts

13 Experts available now in Live!

Get 1:1 Help Now