the tracking pixel

A tracking pixel is a graphic that mostly has dimensions of only 1x1 pixels. Thus, it is so small that it can hardly be seen by visitors of a website or email recipients. In order to remain hidden, these tracking pixels are partly or fully designed to be transparent, or camouflaged in the background color of the website. Users are usually not supposed to see the tracking pixel
 The tracking pixel URL is the memory location on the server. When the user visits a website, the image with the tag is loaded from this server


Tracking pixels within the source code might look like this:

PART OF THE CODE TO DETECTION:

 var extension = (/[.]/.exec(href)) ? /[^.]+$/.exec(href) : undefined;

                    var filePath = href;

                    _gaq.push(['_trackEvent', 'Download', 'Click-' + extension, filePath]);

                    if (jQuery(this).attr('target')

THEY USE THIS PROTOCOL : 

 
Eddystone-UID frame broadcasts

AND THIS TOP LEVEL ESPIONAGE ON BLUETOOTH

BLE

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Step 1

Make a directory inside your "tessel-code" folder: enter mkdir ble into your command line, then change directory into that folder: cd ble

Step 2

Plug the BLE module into Tessel port A with the hexagon/icon side down and the electrical components on the top, then plug Tessel into your computer via USB.

Step 3

Install by typing npm install ble-ble113a into the command line.

Step 4

Save this code in a text file called ble.js:

// Any copyright is dedicated to the Public Domain.
// http://creativecommons.org/publicdomain/zero/1.0/

/*********************************************
This Bluetooth Low Energy module demo scans
for nearby BLE peripherals. Much more fun if
you have some BLE peripherals around.
*********************************************/

var tessel = require('tessel');
var blelib = require('ble-ble113a');

var ble = blelib.use(tessel.port['A']);

ble.on('ready', function(err) {
  console.log('Scanning...');
  ble.startScanning();
});

ble.on('discover', function(peripheral) {
  console.log("Discovered peripheral!", peripheral.toString());
});

Step 5

In your command line, tessel run ble.js
Set a Bluetooth Low Energy device to advertising and see if Tessel can find it!

Bonus: Change the code to print out only the address of discovered peripherals.

To see what else you can do with the BLE module, see the module docs here.

http://start.tessel.io/modules/ble