Gonçalo Valério

Month: December 2017

  • Getting started with Blockchain and related technologies

    Crypto currencies have been at all rage in the last few months, with the price of Bitcoin and other Altcoins skyrocketing and achieving new all time heights.

    This is very interesting and since there is the idea that the technology supporting all of these coins is revolutionary, some saying it can be used to solve many problems that we currently struggle with (or turn thing more transparent). I needed to take a look at how it works internally.

    For anyone trying to understand and work with “Blockchain” and its new style of “consensus”, playing and just using the coins and wallets is not enough. All the things that happen in the background are complex and require the understand of several mathematical properties.

    So where to start?

    There are many books (and I’ve read a few of them), but some just approach the technology from an high level and from a user perspective. Others are good and complete, but very dense.

    I took another approach to complete my understanding of the internals of the technology. I joined and recently completed the online course of “Bitcoin and Cryptocurrency Technologies” from Princeton University, available on the Coursera platform.

    The content, even though the course dates from 2014/2015, is solid. It covers the basic concepts and the internals of bitcoin very well, foundational things that do not change that often. Content isn’t just thrown at you, they build up your knowledge on the matter.

    The only issue, in my humble opinion, is the timing of the first graded assignment, which is given to you before the lessons on those concepts are explained (but you can watch those lessons and comeback to the assignment later). On the remaining assignments some context and better explanation of the terms on the code might help, but eventually you end up understanding what they mean. Otherwise the discussion forums will guide you in the right direction.

    Overall, truly recommend this course (that is free at the moment) if you desire to get an initial and deeper knowledge of the system and not just the user perspective.

  • Making the most of your dusty Raspberry Pi

    Raspberry Pi was one of those projects that were “godsent” (just like Arduido). A cheap and very small computer that would let the little ones and also older folks learn, explore, prototype and build lots of things that  previously would be inaccessible to many.

    So in this post I want to give you some tips and ideas of things you could do with that Raspberry Pi you have unused in the drawer. The main objective is to set it up once, configure some services and utilities that are useful in several areas.

    Protect the entire household from Ads

    One awesome project you can easily install on your device is Pi-hole, which you can setup with a simple command and by changing the DNS entries of your router’s DHCP settings, it will let you have all of the devices in your network automatically “protected” against those Ad networks that try to track your Internet usage.

    Protect your communications when not at home

    Other tool that is very easy to setup and can help you when you are abroad or using insecure networks, is the PiVPN project. You will be able to create your own virtual private network, that will route your communications through your chosen network (home network for example), protecting the traffic and also letting you access your devices that are on the given network as well.

    Extra Tip: Use this together with the Pi-hole’s DNS server to block the advertisements and tracking requests anywhere you go, by adding:

    push "dhcp-option DNS <IP OF YOUR PI'S TUN0 INTERFACE>"

    to your “/etc/openvpn/server.conf” (a restart is needed) and changing the “Interface Listening Behavior” to “Listen on all interfaces” on Pi-Hole’s administration.

    Check who’s at Home or at the office

    This one is a little more tricky to setup, but it might worth it when you need to know when somebody is at home or at the office. The Pi-sensor-free-presence-detector, makes use of your local network to check which devices are connected and then you can link to a person based on who’s the owner.

    Other Stuff

    For those who want to take things one step further and take control of many of the usual web applications you can take a look at the Freedom Box project. You can install it on your Raspberry Pi and configure many applications on your own server.