OwnTracks Encrypted Location Node-RED Node

OwnTracks Logo
OwnTracks Logo

At the weekend I ran the London Marathon, while I’m glad I did it, I have no desire to do it again (ask me again in 6 months).

My folks came down to watch me and to help them work out where on the course I was I ran with a phone strapped to my arm running OwnTracks. This was pointing at the semi public broker running on my machine on the end of my broadband. In order to keep some degree of privacy I had enabled the symmetric encryption facility.

As well as my family using the data I had run up a very simple logging script with the mosquitto_sub command to record my progress (I was also tracking it with my Garmin watch, but wanted to see how Owntracks did in comparison).

# mosquitto_sub -t 'owntracks/Ben/#' > track.log

Before I started I hadn’t looked at what sort of encryption was being used, but a little bit of digging in the src and a pointer in the right direction from Jan-Piet Mens got me to the libsodium library. I found a nodejs implementation on npm and hacked up a quick little script to decode the messages.

var readline = require('readline').createInterface({
  input: require('fs').createReadStream('track.json')
});

var sodium = require('libsodium-wrappers');

var StringDecoder = require('string_decoder').StringDecoder;
var decoder = new StringDecoder('utf8');

readline.on('line',function(line){
  var msg = JSON.parse(line);
  if (msg._type == 'encrypted') {
    var cypherText = new Buffer(msg.data, 'base64');
    var nonce = cypherText.slice(0,24);
    var key = new Buffer(32);
    key.fill(0);
    key.write('xxx');
    var clearText = sodium.crypto_secretbox_open_easy(cypherText.slice(24),nonce,key,"text");
    console.log(clearText);
  }
});

Now I had the method worked out it made sense to turn it into a Node-RED node so encrypted location streams could easily be consumed. I also added a little extra functionality, it copied the lat & lon values into a msg.location objects so they can easily be consumed by my node-red-node-geofence node and Dave’s worldmap node. The original decrypted location is left in the msg.payload field.

Owntracks node

The source for the node can be found on github here and the package is on npm here.

To install run the following in your ~/.node-red

npm install node-red-contrib-owntracks

New Weapon of Choice

I’ve finally got round to getting myself a new personal laptop. My last one was a Lenovo U410 Ideapad I picked up back in 2012.

Lenovo U410 IdeaPad
Lenovo U410 IdeaPad

I tried running Linux on it but it didn’t go too well and the screen size and resolution was way too low to do anything serious on it. It ended up with Windows 7 back on it, permanently on power because the battery is toast and mainly being used to sync my Garmin watch to Strava.

Anyway it was well past time for something a little more seriously useful. I’d had my eye on the Dell XPS13 for a while and when they announced a new version last year it looked very interesting.

Dell have been shipping laptops installed with Linux for a while under a program called Project Sputnik. This project ensures that all the built in hardware is properly supported (in some cases swapping out components for ones known to work well with Linux). The first generation XPS13 was covered by Project Sputnik so I was eager to see if the 2nd generation would be as well.

It took a little while, but the 2015 model finally started to ship with Ubuntu installed at the end of 1Q 2016.

As well as comparing it to the U410, I’ve also compared the XPS13 to the other machine I use on a regular basis, my current work machine (a little long in the tooth, Lenovo w530 ThinkPad). The table shows some of the key stats

U410 IdeaPad W530 ThinkPad XPS13
Weight 2kg 2.6kg (+0.75kg) 1.3kg
CPU i5-3317U i7-3740QM i7-6560U
Memory 6gb 16gb 16gb
Disk 1tb 512gb 512gb (SSD)
Screen 14″ 1366×768 15.6″ 1920×1080 13.3″ 3200×1800

The one I like best is the weight, lugging the w530 round is a killer, so getting to leave it on the desk at the office a little more will be great.

Dell XPS13
Dell XPS13

As for actually running the machine it’s been very smooth so far. It comes with Ubuntu 14.04 with a couple of Dell specific tweaks/backports from upstream. I’m normally a Fedora user, so getting used to Ubuntu for my main machine may take a bit of getting used to and 14.04 is a little old at the moment. 16.04 is due to ship soon so I look forward to updating it to see how it fairs. I’ve swapped the desktop to Gnome Shell instead of Unity which is making things better but I still may swap the whole thing for Fedora 24 when it ships to pick up something a lot closer to the bleeding edge.

One of the only things missing on the XSP13 is a (normal) video port. It does have a USB-C/Thunderbolt port which can support HDMI and Display Port but the driver support for this on Linux is reported to still be a little brittle. While I wait for it to settle down a little I grabbed a Dell DA100 adapter. This little device plugs into one of the standard USB 3.0 port and supplies HDMI, VGA, 100mb Ethernet and a USB 2.0 socket. This is a DisplayLink device, but things seam to be a lot better than when last tried to get a DisplayLink to device to work. There is a new driver direct from the DisplayLink guys that seams to just work.