MyBookshelf2 – ebooks management and sharing solution moved to next version – Beta 2 – apart of few small fixes, the main change is an internal revamp to make it compatible with latest Asexor and thus removing dependence on Crossbar.io and Autobahn library. It makes deployment of MyBookshelf2 easier and removes components that did not add much value to the solution, just made it bit overcomplicated. Some effort was given to provide easy implementation in Docker – now there is a script that will guide you through two pre-configured scenarios – development (local code, monitoring of code changes) and stage (code in a volume, JS client built and packed, app server running behind nginx proxy with SSL termination, nginx serving static content).
I’m big fan of audio books. During past years I’ve been using setup described in this article (libresonic server, android client, audio encoded with opus codec) for audio books listening. It works well for me , but it’s best with audio books split to chapters or to parts not longer then 1 hour. However some audio books come in one large file (m4b format, or aax proprietary file from Audible). To listen to such audio books conveniently I need to split them. Luckily with ffmpeg tool and a bit of bash scripting it is not difficult. Continue reading Splitting Large Audio Books
In IT there are big things and there are small things. Some small things can be pretty annoying and they seem to stay here forever. One of these annoying little things is difference between restrictions for file names in Windows versus unix/linux (others are for instance legacy character encodings, http proxy support, these things has teased me many times in past). Have you ever seen strange file name like W3NEM5~I on shared disc instead of meaningful file name, that you expected? If so and you’re interested what’s going on continue reading. Continue reading What Is This Weird File Name in My Samba Share?
As Canonical has announced the end of Unity desktop I thought it’s time to look again around at Linux desktops. In past years I have been using mainly Gnome 2 (or Mate recently), XFCE, Cinnamon and Unity (yes I did and experience was after all rather positive). I’ve tried Gnome 3 few years ago, but really never gave it longer try and never really find attraction for KDE. So in this article I’ll look a bit at those desktops again and especially at the recent Gnome Shell and it’s customization to my needs (which is indeed based on very individual preferences). Continue reading Linux Desktop for 2017 and on
By default mount is using async option, which means that write operations do not wait for final confirmation from the device – they are stored in disc cache and writes are done latter, optimized by disc firmware. However you can set sync option manually (
-o sync), then write operations are synchronous, meaning each block write has to wait for confirmation that it’s physically written to the disc and there is no optimization available. This can significantly slow down write speed, of which I convinced myself just recently – I backuped some data to external 2.5″ USB 3.0 HD – slowdown in this case was almost 1000x – (70kb/s vs 60MB/s measured by
rsync --progress). How it happened that disc was mounted with sync option? I actually use usbmount to auto-mount disks and it has sync as default mount option (fortunately can be changed in it’s configuration). So conclusion is – don’t use sync option unless you know exactly what you are doing and if write speed is suspiciously slow check mount options.
In todays digital world passwords and other types of secrets are omnipresent and they secure access to various assets dear to our hearts, some of those can have tremendous tangible or moral value. For such assets it’s worth to select really good and strong password, which basically means long and hard to remember. How to ensure ourselves in case of memory failure? We can write it down and lock in secure place, share with trusted person etc., but still there is one point of of failure – secure place can be robbed, that person can betray us. Can cryptography provide us with better options? Yes it can with help of method called Secret sharing – we can split secret into n parts – called shared secrets – and distribute them to different places/people. Later we (or someone else) need to collect k (k > 0 and k <= n) shared secret to recover original secret. k is called threshold and it is defined when generating shared secrets – so we for instance generate n=5 shared secrets, but only k=3 will be needed to recover original secret.
I believe you can easily imagine many other real life scenarios where secret sharing can be useful and for sure it’s used in many applications and systems today. Cryptography provides several algorithms for secure (by design) secret sharing. Most common is Shamir’s Secret Sharing based on linear algebra approach. There are many tools and libraries for Shamir’s scheme (and further advancements of original algorithm), you can for instance try ssss, which provides command line tool that you can easily install into your Linux and also there is an online demo. Another family of secret sharing schemes is based on Chinese Reminer Theorem, where especially Asmuth-Bloom scheme is interesting. I have not seen many implementation for Asmuth-Bloom secret sharing so I created one in Rust. Continue reading Secret Sharing Is Caring Too
Container as a Service (CaaS) is increasingly popular cloud service (usually categorized under Platform as a Service family of cloud services). It can provide easy ways how to deploy web applications leveraging Linux container technologies usually most popular Docker containers. Recent addition to this family is Openshift v3 from RedHat. Openshift is available as an open source software (Openshift Origin) or as a hosted service (OpenShift Online). I already used previous version of Openshift service (v2), as described in my previous article. In this article I’ll share my recent experiences with Openshift v3 service (also called NextGen). Continue reading The Splendors and Miseries of CaaS – Experiences with Openshift3
In past article I’ve written about some basic stuff we can do with Ethereum client Parity – like transfering Ethers, creating multi-signature wallet and even writing our own contracts. Now I’ll continue with writing our very own Distributed Application ( Dapp). Continue reading Writing Distributed Application for Ethereum
In past article I’ve talked generally about blockchain technologies, in this article we will look into Ethereum from user perspective. We will build local playground, where we can test many functions of Ethereum(Ethers transfers, using and writing smart contracts and more) without spending real Ethers (and thus real money). This guide in intended for users with Linux OS. Continue reading Ethereum local playground
Some technologies I really notice only when they hit me directly into the face. That’s the case of blockchain – I have been looking into Bitcoin several years back and found it quite interesting (especially from cryptographic perspective – as interesting usecase for applied cryptography), but never expected that it’ll reach such extensive grow in popularity as we have seen in past half year or so. This forced me to looked again into these technologies and get bit more detailed understanding about blockchain technologies, why it’s so popular now and particularly look at recent development and on next big player in this area Ethereum project.
In this article I’ll share some initial thoughts of mine about blockchain, what I think it is and why it matters. In later article(s) we’ll look into Ethereum from purely practical perspective. We will build a local playground for Ethereum, where we can try immediately some basic functions of the system. Continue reading Blockchain madness