Using tcpdump for capturing data sent by TK102 GPS tracker

Xexun TK102 GPS Tracker and most of its clones can send localization data either via SMS messages (some models offers just a pure data, that you have to analyze yourself, some sends it out along with Google Maps link) or via GPRS protocol, directly to specified server. Which then can analyze and visualize that data. SMS sending works just great in most cases, while getting GPS data via GPRS can be a real pain in the ass. This post is written with hope to help you a little bit, if you’re facing the same problem.

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TK102 connector / plug / cable type (and schematic diagram)

The Xexun TK102 GPS Tracker and most of its clones is using something, what English Wikipedia calls UC-E6 proprietary (non-USB) plug. So, this is neither microUSB nor miniUSB as I was assuming in the first place.

Here you’ll find some links to information about this plug and some simple schematic diagram for tracker.

Here is mentioned schematic diagram:


If you’d like to purchase a cable for Xexun TK102 GPS Tracker, then eBay should be your friend. If, on contrary you’d like to craft your own cable, then this great article will help you or can be at least a good starting point.

Xexun TK102 GPS tracker master password reset

Many sellers will tell you, that if you forget your master password (if you change it ever from default 123456, as you should do), then you’re deep in black ass, and the only option for you, is to send tracker to them or to the producer, to reinstall (re-flash) original firmware. This is lie in most cases and probably it is aimed to fool people paying extra money for reseting tracker, they can easily reset themselves. Here is how.

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Fixing graphic problems in Diablo I and Diablo II

I’m so sucking and low player that actually for past fifteen (!) years I’ve been playing in actually four games: Diablo I, Diablo II, Civilisation and Transport Tycoon. The first two caught my heart so deeply that I even try to run them (Diablo I!) on Windows 7. And… I actually managed to do this.

Since, this involved a lot of googling and asking, here is a summary of my findings.

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Enabling remote access to Asmax AR1004g router

To access your Asmax AR1004g router remotely (i.e. from WAN / Internet side, not from your local network), you have to remember about two things. Because I nearly always forget about one of these things (or about both in the same time), I wrote this simple memo-post as a reminder to myself.

In this post you may also learn how stupid are Asmax engineers and designers.

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General info on Xexun TK102 GPS tracker

This is general post about Xexun TK102 GPS tracker and many of its clones. You’ll find here a bunch of useful information, including some tech specs, list of differences between original tracker and clones and some more.

The localizer and its clones

We’re talking about “Xexun TK102 Tracker” here. The original one, because there are many clones under other companies from China, selling similar hardware, with the same cover and logo, but with:

  • lesser performance (able to report location once per 20-30 seconds, not once per 5 seconds),
  • lesser information (lack of direction/bearing, altitude, number of satellites used for location fix and more),
  • different format of data or non-standard protocols (unable to use UDP protocol, using non-standard data packets).

“Coban” / “Kintech” are just two of many clones sold on eBay etc., claiming to be original “Xexun” trackers.

On the other hand, original “Xexun” and some clones (like “Coban” for example) are harder to control from own script, because they require a correct answer from the server, where data is sent over GPRS. If unit does not receive such reply, it breaks connection. The cheapest unit does not have this checking and will always sent location data to specified IP address over provided port.

Product description

Here is product description of original “Xexun” localizer (and here is a clone under “Kintech” name).

Possible buyer must be very careful (and should secure return policy, for which buying directly in China is not recommended) as there are many reports about sellers claiming to sell original “Xexun” device and sending a clone actually.

Though this device is five years old, it is still sold at many places (including eBay), but even at theses sources it is very hard to get anything worth for developers, except some simple, very basic user guide.

I have confirmed information (from two different sources) that there is no official API available for this device. The only option is to Google around, ask other users or use forums (see below).

If you own original “Xexun” localizer, you may try to contact company international departament and ask their technicians to include some changes to device source code and to send you updated firmware, with your changes – wow! That was confirmed by company itself.


I found a perfect forum for TK102 device, with a lot of questions and answers:

  • here is a general forum on TK102 device (kept alive for 5 years with 174 pages and 2000+ posts!),
  • here you’ll find more specific topic on receiving data from this localizer,
  • this forum is also about TK102 unit, but it is entirely in French.

There are many other devices dissussed and in general, this is the biggest forum in the world, with topics for localizers and similar information.

GPRS Protocol Specs

In general, any TK102 related devices is opening a socket for a direct TCP transmission (original one can be switched to use UDP protocol). Data is being transmitted over port specified by user, in configuration and using GPRS only (requires SIM card with enabled GPRS, there is no way to use WiFi).

Sending frequency, format and amount of data being send, entirely depends on kind of device is being used — it is more extensive and more configurable in original one than in clones.

Correct server response problem

Take into consideration, that many TK102 clones requires a correct response from the server after each data, it send. It breaks connection after sending some welcome garbage UDP packet, as it does not receive response, it waits for.

It is quite hard (quite impossible?) to find any guide to many of these clones, on what kind of responses server should sent. This often leads into situation of developer being unable to establish two-way communication between server and localizer. Many localizers are sold to be used only via SMS communication or throughs paid services that had signed and agreement with producer and received protocol specification that contains valid responses server should generate for particular TK102 clone.

Double check, if this is not source of problem, if you can’t communicate with your localizer from your app.


This is all the information, I managed to get up until now. I don’t found any API for this tracker so far. I found some technical documentation, but it did not helped me much in the area of programming this device on server-side. If you need more information, look around this blog or make Google your friend.

Configuring NAT, DMZ or Virtual Servers on ASMAX AR1004g

This is a very short brief on how to properly setup NAT functions on ASMAX AR1004g router, i.e. how to route all (or part of) incoming traffic to a specific machine in your local network. In this text, I assume that your router is available under static IP address in your local network and you want to route all traffic using FTP protocol to your video-player, available under and all traffic using HTTP to another computer, that is accessible under static IP address in your local network. Adjust this assumption to your actual situation. Read More “Configuring NAT, DMZ or Virtual Servers on ASMAX AR1004g”

FujitsuSiemens AmiloPro V2060 no HDD found

When installing Windows XP Professional on FujitsuSiemens AmiloPro V2060 laptop in most cases it will turn out, that the hard disk is not found. This is because many Windows XP Installation CDs do not contain drivers for the Intel SATA HDD support, that is available in AmiloPro family of FujitsuSiemens laptops. This article may help in this situation.

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