I’ve been interested for the crypto world for a few months now and I’ve acquired a ming rig, otherwise I wouldn’t feel complete 🙂

For all of you that have a mining rig, you’re probably familiarised with those tiny usb devices that you stick in a usb port to monitor your computer and reset it in case it hangs/freezes.


This is known as a usb watchdog and the way it works is very simple:


  1. Connect this device to a USB port. The usb watchdog has 4 pins: 2 that should be connected to the power switch and another 2 for the reset button. Use jumper wires to make the connection.
  2. When the watchdog gets powered on, it will wait for x amount of time for you to tell him “Hey, I’m still a alive! Wait for x more seconds and if you don’t get back from me again then please reset the computer”.
  3. Repeat the previous step indefinitely

Those messages are sent by a specific software. If for some reason your computer crashes,  then the watchdog won’t receive another message from the software. If a message is not sent within those x seconds, the usb watchdog will know that something isn’t right and it will issue a hardware reset simulating the physical push of the reset button.


This usb watchdogs are shipped with dedicated software, which in my case is pretty useless because it was made for Windows computers and my mining rig is linux based. I could try to use wine but I don’t feel like killing flies with bazookas.


The windows software seemed pretty basic how hard could it be to reverse engineer the protocol?


Couldn’t be easier:

The first thing was to find some software that could inspect the connection and check what was being passed back and fourth. The first link provided by google was all I needed. I’m talking about this one.

Using a Serial port sniffer it was pretty obvious to understand the patterns.  First let’s check the serial port settings:

  • Baud rate: 9600
  • Parity bits: None
  • Stop bits: 1

This is enough for you to start sending messages to the usb watchdog.

The protocol:

The only thing that you need to know now is the protocol. The sniffer will give you a good picture of it.
First of all, whenever you open the watchdog software, you can see that it sends a packet (0x80) which then get an answer from the watchdog (0x81). I’m not entirely sure of how data is encoded but it’s pretty clear that whenever the software connects, it presents you with a message containing the firmware version. I would say that this is probably encoded here in this byte.

Then you can see a sequence of bytes (0x10) that are being sent at a rate of 1/s. The timeout value was set to 160 seconds. If I set the timeout value to 10 seconds, the application will start sending 0x01.

So, if 1 equals to 10 seconds, 160 seconds should be equal to 16. What is the hexadecimal representation of 16? You guessed it: 0x10 🙂

If click on the reset button, a 0xff is sent and the relays are triggered.

As far as I know, there are only these three operations available:

  • Reset
  • Send a heartbeat with the current timeout value.
  • Check firmware version


The script


If you were expecting something fancy, you’ll be disappointed, but the sources are available here: https://github.com/zatarra/usb-watchdog 🙂
Basic functionality is implemented but you might want to extend it. You can test your video cards, test an internet endpoint, or you could even remote restart your mining rig.  Use your imagination! 😀


Warning: Do not set the heartbeat interval to a very low value, such as a minute. If you do that and your computer crashes,  you will have one minute to complete the boot process and load this script. If your computer fails to do that it will get stuck in an infinite loop which sucks if your mining rig is in a remote location.


Check my repository for the latest version of this script.


If you find this useful, buy me a beer: 😀

bitcoin: 3Mj3v5hrx5qQhwzzWPMGwkJ8DRMCywhZFy
bitcoin cash: 1KDbjLM9DdsCyfDMSYHdm52r5R3BRP2dfS
ethereum: 0xfF7167e9ea8A4d882dd9161FC5F1560B9031A6c6
litecoin: MERSbMVM9NmQoDhr5ktswpaumWk8dGbyUu
ripple: rN1sXzZUBej2wiZSjgKtAgNRTUoFhUdt36 


For those of you that are into digital currency and have been following Monero, you probably know by now that an ingenious web based miner was created, allowing people to monetize websites by using some cpu cycles from their visitors.

Unfortunately this has been used in malicious ways ( e.g. here and here ) which pushed it to several Anti Virus’s blacklists or popup blockers.

Since then, the original developers tried to create a alternatives to clear CoinHive’s image, but at this point it might be complicated to revert all the actions that were set in place to stop its usage as malware.

For now, you might be better off running your own cluster ( to avoid issues with anti virus or adbockers ) and to do that you need to use a middleware that translate’s coinhive’s custom protocol to something that most of the mining pools can understand: stratum protocol.

That’s where this neat tool enters. CoinHive Mining Stratum Proxy is a Python tool that can act as a proxy between your website clients and a mining pool. This is particularly important since coinhive.com is blocked by several security tools.

The original tool was already a great tool, but I’ve decided to add SSL support and make the command line more clear regarding to the accepted parameters. Another nice feature the ability to check how many clients are currently connected and how many hashes were accepted.

Feel free to check out my version here https://github.com/zatarra/coinhive-stratum-mining-proxy and the original version here. I’ll open a pull request to the original project once I complete the tests for these new features that I’ve added.

Talvez por os tempos serem de crise, tenho andado a pensar nos últimos tempos como rentabilizar ao máximo os fundos de que disponho actualmente. A ideia é pegar numa determinada quantia e fazer uma aplicação durante alguns anos reinvestindo todos os anos o valor inicial incluindo os juros ganhos.

Criei um simples simples script que me efectua este calculo. Já existem calculadoras destas às paletes, apenas criei uma nova para simular variações nas taxas de juros entre os vários anos.

A ideia é simplesmente utilizar como limites de variação de juros fornecidos pela instituição financeira e assim tentar ter uma ideia mais real (que na realidade até pode ser bem menos real) do resultado final.

Utilizem o seguinte formulário para efectuarem o calculo:



Já chegaram as duas competições que te podem levar a passar umas férias no outro lado do mundo, ou a passear pela Europa no teu novo Mercedes.

São eles a XTB Trading Cup e o Jogo da Bolsa do Jornal de negócios.

O objectivo é simples: Investir uma determinada quantia de dinheiro virtual em instrumentos financeiros e rentabilizar ao máximo durante um período de tempo. No final, ganha quem tiver ganho mais.

Os prémios são no mínimo muito aliciantes. Na XTB Trading Cup o primeiro prémio é nada mais nada menos que um Mercedes SLK. Haverá ainda prémios para o segundo classificado e para os vencedores semanais.

No caso do Jogo da Bolsa os prémios são mais simpáticos, mas não deixam de ser bastante aliciantes. Para o primeiro classificado será entregue um cheque de quatro mil euros, com prémios garantidos até ao quinto lugar. Tal como no concurso patrocinado pela XTB, aqui também haverá prémios para os vencedores semanais.

Mais informações no site oficial do Jogo da Bolsa e no site da XTB Trading Cup.