Tabla de contenidos para No. 184 en Linux User & Developer

Welcome to the UK and North America’s favourite Linux and FOSS magazine. Ever wondered where all your taxes go? Well, in the UK a chunk of it is merrily flung down a closed source software hole that public administrations are destined to fill again and again in a Sisyphean nightmare (and a government contractor’s sweetest dream). The Free Software Foundation Europe is running a campaign to raise awareness of this waste of taxpayer’s money (see p9 for the full details). Note: If you’re in the US, check out https://code.gov and consider writing to your representative to ask them to increase the current requirement to open-source 20% of new code that’s commissioned. In the rest of the magazine, we’ve homed in on the command prompt with our bumper feature on working…

Top 10 This month Stable releases (21) In development (6) Updates were released for three security-focused distros, which offer pen-testing tools, anonymous browsing and computer forensics software. Highlights Subgraph OS Debian-based Subgraph OS offers provides several security, web anonymity and hardening features. Among them are a hardened kernel and application firewall, while all internet traffic is routed via Tor. Email encryption is supported, while the file manager strips all metadata. Parrot Security OS Based on Debian, Parrot Security OS is a security-focused distro that bundles standard features alongside pen testing, cryptography, privacy, ethical hacking and other utilities. Ships with the MATE desktop environment. Kali Linux Another Debian-based security distro, this is the most well-known Linux penetration testing system. Packed with security and forensics tools, Kali Linux also supports ARM…

“The general public is as in the dark as ever about how their tax money is squandered” The Free Software Foundation Europe’s ‘Public Money? Public Code!’ campaign wants to curb the trend for using closed software and proposes that all software developed using public funds be made publicly available as free software. The campaign is designed to inform the general public about how there are several good reasons for this, about how, despite the fact we are paying for closed software now, we are not benefiting from it. Quite the contrary: often we are suffering because of it, as we are paying more for useless reinventions of the wheel every time a public administration needs a piece of software that another already has, but decided not to share. As a…

So, what is Intel Management Engine is and why might users want to deactivate it? Imagine if there was a ‘black box’ operating at the lowest level of your Linux machine with control over every part of the system and you couldn’t access this box or control it. Well, if you have an Intel CPU that’s what you’ve got and it’s called Intel Management Engine (ME). ME is an independent processor core that’s embedded inside the Multi-Chip Package (MCP) on Intel CPUs. This operates independent of the main processor, the BIOS and your operating system, but it interacts with the BIOS and OS kernel. Recently, there were vulnerabilities found in some Active Management Technology (AMT) modules which exist inside some Intel Management Engines. These AMT modules (or what Intel calls…

“Open innovation drives innovation exponentially compared to closed, but they failed to grasp that” Acute flaccid myelitis (AFM) is a rare condition that affects the nervous system and has about a 2% recovery rate. The starkness of a medical statistic like this is brutal, and even more so when they relate to the health of your own children, but this was what Bodo Hoenen and his family were facing in the summer of 2016 when their five-year-old daughter, Lorelei, was diagnosed with AFM. The condition particularly affects the spinal column and in Lorelei’s case it had paralysed her left shoulder and left arm. “The prognosis was that the only thing that would help was occupational therapy and physiotherapy,” says Hoenen, “but looking at the results, back then, there were only…

>_41 List running processes This lists all processes running on your computer – you may be surprised at the number. This sort of command really needs to be piped to a pager or grep to find what you are looking for. 42 Show resource users Run top to see a list of processes sorted by CPU usage, along with overall stats on processor and memory usage. The results are sorted by CPU usage by default, but you can use the command keys to sort by a different criterion – press H to see the many options. 43 Kill a process Use kill followed by a process number, gained from ps or top, to send a TERM command to it. This tells the process to shut down cleanly. If it refuses…

>_71 Mount a file system The command to mount a file system is: sudo mount /dev/sdXn /mount/point …where sdXn is the device node. The mount point can be anywhere. The file system is usually detected automatically, or you can use -t to specify. >_72 Copy a complete file system with dd …will make a bit-for-bit copy of the disk partition to the given file. It will be as large as the original partition, so you may want to pipe the output through a compressor: >_73 Another way to mount If a device is listed in /etc/fstab, you need pass only the device or mount point to the mount command and it’ll read all other options from fstab. If fstab contains user or users in the options field, the file system…

Establishing an online presence is a task easily accomplished with a personal website. While websites are a great platform to showcase your skills, there’s no reason we can’t show off our Arduino prowess and avoid paying money to host content on a server at the same time. This month we are going to begin a series of Arduino tutorials that take the microcontroller board out of its comfort zone and we start by transforming it into a simple HTTP web server. Alarm bells should be ringing in your head right now: aren’t Arduinos meant for hardware projects? Well, yes entirely. Arduinos also have a maximum program size and a relatively small amount of memory, making this difficult. We could also do this cheaply with an actual, albeit small, computer such…

01 Encrypt your data During the installation of Kali Linux (and other pen-testing distros), you will be given the choice of setting up LVM and LUKS to encrypt your partitions. Don’t hesitate to do it, and do not forget to encrypt the swap partition also. In case your computer is stolen, this will prevent unauthorised users from accessing to any sensible data extracted during a pen-test. 02 Put a leash on your output packets! Use iptables to set up proper rules for the OUTPUT chain in order to prevent undesirable output packets going out your network interface: first, drop everything: iptables -P OUTPUT DROP. Next, add the rules you need to the chain along the way; for example, DNS resolution: iptables -A OUTPUT -o eth0 -p udp -d SERVER -dport…

Using some basic Python code, we’re going to read and write directly from text files saved on your computer into your Minecraft world. Steve (or Alex) will be chatting in game from a pre-written script. This simple chat bot could have all kinds of applications – as with all things Minecraft, the limit is your own imagination! This tutorial is written with Minecraft Pi Edition in mind, but you don’t have to be running Minecraft on a Raspberry Pi to follow along. We’ve put together a little package that will work on any version of Minecraft, so if you would like to run this tutorial on your favourite flavour of desktop Linux, Pi or no Pi, you can do. To allow Python to hook into Minecraft, you’ll need to install…

"Doing 3D mathematics on a curved surface can be messy" The Raspberry Pi platform allows for projects where you can bring a computer with you when you go out into the field to do research. One of these research areas is geodesy (and geomatics), which is the branch of applied mathematics that’s concerned with measuring and understanding the Earth’s geometric shape. As you may have suspected, doing three-dimensional mathematics on a curved surface can be a tad messy. Hence the need to have some robust computing handy. The traditional way to do field work is to go out and collect measurements, then go back to the office. This month, we’ll look at a Python module called PyGeodesy which can be used to handle these types of calculations. This isn’t available…

RAM 4GB Storage 32GB disk space Specs 64-bit Intel or AMD processor Available from: www.qubes-os.org In the six years of its existence, Qubes OS has established itself as arguably the most popular security-centric distribution. The reason is that the distro is unique in its approach of isolating the several essential elements that constitute an operating system inside different virtual machines. Essentially, this compartmentalisation helps contain the fallout in the event of security breach. The developers have recently unveiled the first release candidate of Qubes OS v4.0, which has been under development for over a year now. A majority of the changes in this release are behind the scenes, many of which also manifest themselves in terms of changes to how users interact with the distro. The early years of Qubes…

Use the powers of ddrescue from the convenience of a GUI If you’ve ever lost data due to hardware failure, chances are you have been asked to make block-level copies of the failing drive first with the venerable ddrescue utility before attempting to rescue data. The best thing about ddrescue is that it doesn’t write zeros to the output when it runs into bad sectors in the input. So, every time you run it on the same output file, it tries to fill in the gaps without wiping out the data already rescued. The only downside is that ddrescue is a CLI utility and you need to read through its man page before you can use it productively. DDRescue-GUI, as the name suggests, wraps the powerful utility inside a graphical…

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DISTROS In the FileSilo you will find the latest version of the impressive Manjaro Linux Xfce Edition 17.0.5, Parrot Security 3.8 and Tiny Core Linux 8.1.1. SOFTWARE We’ve packed in a lot of tutorial code this month, but we’ve stilled managed to squeeze in all the Python code editors – Eric, PyCharm Community Edition, PyDev and Thonny – that were in the group test. TUTORIAL CODE You’ll find all the resources needed for Python/Minecraft, the Enviro pHAT ghost detector, the Java game and the OVA file for the pen-testing challenge! Subscribe & save! See all the details on how to subscribe on page 32 Log in to www.filesilo.co.uk/linuxuser…

ABOUT Eating Robots Taken from the new book Eating Robots by Stephen Oram: near-future science-fiction exploring the collision of utopian dreams and twisted realities as humanity and technology become ever more intertwined. Sometimes funny and often unsettling, these 30 sci-fi shorts will stay with you long after you’ve turned the final page. http://stephenoram.net Christopher’s neck was bruised where they’d held him down while forcibly removing his arms and legs. He’d fought them hard, but it had been pointless; here he was, dumped by the side of the road in an old, damp car seat, helpless and homeless. Tears were rolling down his face and he could do nothing about them. How could it have come to this? Less than a year ago he’d taken an affordable loan from a company…

These days, in theory, there is no necessity to use the command line to run and maintain a Linux system: there are so many graphical tools available for most tasks. But when did we start doing only those things we absolutely had to? The command line provides an alternative environment to the typical desktop GUI, with its own set of pros and cons. The main advantage is that if you know what you are doing, many tasks can be accomplished more efficiently in the command line. That’s just for single tasks, if you want to do something to ten files in a GUI it will often take ten times as long, compared with an extra couple of seconds on the command line. Another time the shell is important is when…

21 Starting and stopping services Your computer runs many services, also known as daemons, in the background. On distros using the older SysVInit service management, these are controlled by scripts in /etc/init.d, so you would start Apache with: /etc/init.d/apache start 22 Service status As well as the start example given above, and the corresponding stop, some service scripts also take a status option that tells you whether the service is running or not. 23 Services systemd style Systemd uses the systemctl command to manage services, so you can start one with something like: systemctl start apache2.service There are corresponding stop, restart and status commands, which all do exactly what they say. 24 Listing services SysVInit users can simply use ls /etc/init.d, while systemd users can use systemctl list-units to see…

Between them, the two Voyager spacecraft have visited all the outer planets – Jupiter, Saturn, Uranus and Neptune – and many of their moons. Both are now heading into interstellar space; Voyager 1 became the first man-made object to leave the solar system in 2012, and is now 13 billion miles away. Amazingly, it’s still in contact with NASA. And, just in case they are ever found by extra-terrestrials, each craft carries a gold disc containing sounds and images portraying the diversity of life and culture on Earth. Despite representing one of NASA’s most successful space programmes, the Voyager probes do not run Linux. The reason is clear to see. By the time you read this, the Voyager spacecraft will have been in space for 40 years. Linux, on the…

When we think of computer networks, we think of the world wide web, which we can use for sending emails, watching videos or talking to people over video. In fact, all of these are examples of a very simple concept: computers connecting to other computers on a device called a ‘socket’ and using the socket to send text back and forth. The text might be in HTML format, it might be the text representation of an image, and it might even be encrypted, but the same mechanism is used in all cases. The Java language has a rich networking library that allows us to harness this power for our own programs. At the end of last month’s tutorial, we had a simple adventure game to play on a single computer.…

01 Information Gathering We are provided with the company’s network address. We use Censys (https://censys.io) to have a quick look at those servers accessible from the internet first. We are working from outside the company’s network, operating as a Black Hat with no foothold into the network. Censys shows us a bunch of hosts, one of them running a web server tagged as ‘HeartBleed’. 02 Threat Modelling During the Threat Modelling stage, we consider the following vector attack: exploiting the HeartBleed bug to pilfer some sensible data out of the web server. This way, we may be able to grab some credentials or authentication cookies. We have not yet tested for the vulnerability; we are just considering different attack vectors, and this is the first one that comes to mind…

The Pimoroni Piano HAT is an extraordinarily useful board that can turn your Raspberry Pi into an electronic keyboard. The keys are responsive to touch and each one has an LED which can light up as you play. Pimoroni has thoughtfully compiled an excellent library of coding samples for your Pi which enable you to crank out tunes within minutes of receiving your Piano HAT. In this project we will talk you through the basics of attaching the Piano HAT to your Pi, as well as how to use it to generate 8-bit tones and play back piano and drum sounds. You will then learn to use the custom ‘pianohatpassword’ Python scripts to encode a secret message using musical notes. The first script, piano-password.py, allows you to record a musical…

While PyGeodesy provides a lot of core functionality, people doing research will always need to do something new. Many of the underlying calculations are done using NumPy. You can tap into these underlying structures directly to add your own algorithms. You may have some complex calculation that gives you a NumPy array made up of sets of latitude and longitude points. For example, you might have a GPS unit feeding in data over a USB which is then massaged through some form of correction algorithm. You will likely want to make these calculations through NumPy. Once they are done, you can wrap them with a Numpy2LatLon class to hand them in to the PyGeodesy module. As an example, say you had a NumPy array that contains the bounding points of…

Editing videos on Linux is perhaps a similar point to where gaming on Linux was before the arrival of Steam – possible but not very popular. This is strange considering that unlike the pre-Steam gaming era, there are quite a few feature-rich open source video editors within your distribution or its repositories. One of the easiest to get to grips with is OpenShot 2.4 which is a stability-focused release with a majority of the work behind the scenes quashing bugs. That said, the release also improves several existing functions and adds a few new ones as well. One of the highlighted changes is the improvement to how the editor keeps track of changes. By storing the undo/redo actions in a file, the new version also elevates the usability of the…

Following news of the Purism Librem 5 phone, two big hitters in the open source Linux world have announced their attention to get involved. First comes the partnership between Purism and KDE Plasma in a venture that will see a pooling of resources to bring the Plasma Mobile platform to the Librem 5. This is an ideal team-up: KDE Plasma Mobile will gain some up-to-date hardware to base its operating system on, while Purism is set to fulfil its goal of developing a mobile OS with full encryption. But does this mean that Plasma Mobile will be the default OS on the Librem 5? Time will tell, but the initial announcement indicated that a GNOME UI would be employed. Unsurprisingly, the second name to get involved is the GNOME Foundation,…

The growth of open hardware is undeniable and we’ve had high-profile smartphone projects appearing such as Purism’s security- and privacy-focused Librem 5 smartphone ( https://puri.sm/ shop/librem-5 ). The ZeroPhone project led by Arsenijs Picugins is no less ambitious but much less expensive. As we started the interview we noted, with some irony, his apologies for the intermittent mobile connection as he’s taking a break away from his home city of Riga to enjoy the countryside of neighbouring Lithuania. While you’ll be able to make calls and send SMS with Picugin’s ZeroPhone, it isn’t as cutting edge as Purism’s smartphone. Instead, it sits firmly in the middle of the makery and hacking spirit that powers the big budget open hardware projects. The phone’s design is pragmatic, with…

“If things go according to plan, RISC-V will be enabled upstream in Linux 4.15” Linus Torvalds announced 4.14-rc3 (release candidate 3) noting that 4.14 has, so far, been a “somewhat painful release”. He attributes this to “the fact that it’s meant to be an LTS [Long Term Support] release”. This means that 4.14 will receive ‘stable’ backported updates (in 4.14.z updates, such as 4.14.1, 4.14.2 and so on) under the maintenance of Greg Kroah-Hartman (Greg K-H). Greg picks a new LTS kernel periodically and provides fixes and security patches as a means to enable those who are building certain projects to have a kernel source that lives longer than the usual few months. This often includes Android or other major projects that have various channels through which coordination can occur…

Converting document files 31 Office files LibreOffice can run on the command line (with GUI not running) to convert between file types. For example: loffice --headless --convert-to xlsx spreadsheet.ods loffice --headless --convert-to odt letter.doc 32 Extract images from a PDF file pdfimages can extract images embedded in PDF documents; pdfimages -png somefile.pdf someimages will extract all the images and write each to a separate file, someimages-nnn.png. Use -list to list details of the images rather than extracting them. 33 Convert man pages Man pages are written in GROFF, an unusual format. You can convert to PostScript with man -t and then pipe it to your printer or a more readable format: man -t someprog | lpr man -t someprog | ps2ascii >someprog.txt >_34 Image conversion ImageMagick's convert command is used…

>_61 Aliases The alias command creates shortcuts to commands you often use, or add options as default. For instance, some distros alias rm to rm -i to give ‘are you sure?’ prompts when deleting files. You can see the full list of aliases by running alias on its own. If an alias has been created with the name of a command, you can use the original command by prefixing it with \, for example: \rm "somefile". >_62 TAB completion Start typing a command and press the Tab key; your shell with either complete the name or offer you alternatives if there is more than one match. The same applies when typing file or directory names: compare ls /somepath/toavery/longfilename with ls /soTABtoaTABlonTAB. >_63 Running multiple commands Separate multiple commands with semicolons…

>_91 Wildcards Use wildcards to match multiple files. To copy photos in the current directory, use * matches any sequence of characters except /, ? matches a single character. >_92 Handling tarballs If tarballs (file archives) have an extension after the .tar, they’re compressed, but the tar command can still handle them. The first command lists the contents of a tarball; the second unpacks it to the current directory. >_93 Windows ZIP files View the contents of a ZIP archive compressed file with unzip -l somefile.zip; drop the -l to unpack it. >_94 Search a file grep searches files for lines matching a given pattern. To look for error messages in a log file, you could use: grep is case sensitive by default; -i changes that. >_95 Viewing the beginning…

Last month, we saw that Bash scripting can be used as a specialised programming language. Bash scripting is very rich in features, and we met conditionals, variables, for loops, command-line arguments and functions. This month, we’ll be continuing where we left off. Bash scripting supports still more programming constructs, including while loops and case statements. We’ll also be meeting sophisticated ways of chaining and grouping commands, which are particularly powerful when combined with the pipelines that we met in the first article in the series. We learned last month that every command, script and function in a Bash script returns a numerical exit code, and this fact will be important throughout the article this month. Last, we’ll meet a few new useful commands that we can use in our scripts.…

Components list • Raspberry Pi 3 • Mid-1980s FM intercom • 2.3-inch Visaton FR58 8-ohm full-range speaker • Voice HAT accessory board • Voice HAT microphone board • Switch from arcade-style push button • 4-wire button cable • 5-wire daughter board cable Google juice In Martin’s video (http://bit.ly/PiIntercomDemo), he and his 10-year-old daughter demonstrate how they used the AIY Voice Kit to set up their Google Assistant that you can activate with a click of a ‘talk’ button. The intercom has also been used to set up custom voice commands that trigger the lights of a doll’s house and disco lights by activating a WeMo smart socket. The code for the AIY Voice Kit has been updated in significant ways since Martin finished his intercom project and you can change…

As a child, your author distinctly remembers learning that if a ghost or spectre is present, there are several environmental changes that can occur. First, the room may feel colder due to a sudden drop in temperature. Second, objects may mysteriously move by themselves to a new location. Third, you may observe a strange coloured light or a bright white light close to where the supernatural entity is. Pimoroni’s Enviro pHAT is the perfect hardware suite to catch ghosts. It packs four different sensors, letting you measure temperature, pressure, light level, colour, 3-axis motion, compass heading and analogue inputs. They state that “It’s ideal for monitoring conditions in your house, garage or galleon. Set up a web server with Flask and remotely monitor everything from anywhere.” What they failed to…

Price £480 Website  https://bit.ly/gpddroidbox Specs CPU: Intel Atom x7-Z8750 1.6GHz Display: 7-inch 1920×1200 IPS multi-touch Graphics: Intel HD 405 RAM: 8GB Storage: 128GB eMMC Ports: USB C, USB A 3.0, Micro HDMI, 3.5mm headphone jack Connectivity: 2.4GHz/5GHz 802.11ac 2×2 MIMO Wi-Fi, Bluetooth 4.0 Battery: 7000mAh with USB-PD charging support Weight: 480g (magnesium alloy body) Size: 80×106×18.5mm Around ten years ago, the computing world was obsessed with the idea of ultra-mobile PCs (UMPCs). Although there were some impressive devices for the time (the Sony Vaio and Toshiba Libretto, for example), the reality was that the technology wasn’t available to make the machines viable for most users. The small screens were low resolution and low quality, processors were power hungry and ran hot and, most importantly, battery technology meant an hour or…

You can encrypt entire partitions using the installers of many desktop distributions. However, this might be an overkill if all you want to do is keep a handful of files away from prying eyes. Using TruPax, you can easily pack individual files into VeraCrypt/TrueCrypt compatible containers. But why would you use TruPax when you can just as easily use the fairly intuitive VeraCrypt app itself? For one, when creating containers with VeraCrypt you need to have some idea about the size of files it’s going to house. Once created, this encrypted container cannot be resized, which is particularly painful when you find that it doesn’t have enough space for the files. On the other hand, when you select the files you wish to encrypt with TruPax, it creates a container…

Virtually all desktop distributions ship with a default messaging app that allows you to sign into multiple online messaging services. While a great help, these apps track only a handful of popular services. Rambox, on the other hand, has a much wider mandate. With its latest release, you can sign into 89 online messaging and email services! The app is fairly intuitive to use. Every added service resides within its own tab, from where you browse the message history, write messages to your contacts, or use other means of communication supported by the service. The app will also display notifications and parks itself in the system tray. You can lock Rambox when you step away from the computer to ensure no one else can read your messages. Rambox also has…