Linux FormatOctober 2017的目錄

Jonni Bidwell I fulfilled my childhood dream of working for a magazine ending in “Format”. And I read Proust (spoiler alert: nothing happens. Also: those sentences, full of subclauses, rambling meanderings and not a full stop till halfway down the page, wouldn’t get past our production “team”.) Nate Drake Twenty years ago I began my tenure at a Hogwarts-esque secondary school. Notable highlights of my colourful time since then include crashing a tank, sipping vodka in Red Square, studying modern languages (until I discovered Linux) and rediscovering the lost city of Ubar. Adam Oxford I still open up Facebook every now and then, so imagine my surprise when an invite to a 20th anniversary reunion of my graduate class popped up in my newsfeed. I’ve been in the workplace exactly…

“If you want a secure and rewarding career, open source software is the field to be in according to this year’s Open Source Jobs Report, an annual survey of the industry conducted by The Linux Foundation and Dice. Not only did 89 per cent of hiring managers surveyed say that they have difficulty recruiting enough OS (open source) talent, but 86 per cent of professionals believe that knowing OS has advanced their career. Both hiring managers and OS pros agree that the top skill right now is cloud. Forty seven per cent of hiring managers are looking to hire professionals with OS cloud expertise, and 69 per cent of professionals believe cloud skills will gain in importance in the next year. Big Data is also in demand, with 43 per…

A weekend of choices Take part in events up and down the country The last weekend of October 2017 is one of many choices. Across the UK there will be three main events. First off, PyConUK (http://2017.pyconuk.org) returns to Cardiff for four days of Python-related content. This year we see the return of the Raspberry Jam, offering families the chance to get hands-on with Python and the Raspberry Pi, and work with Python developers, but new for 2017 we see the Raspberry Pi Foundation running its Picademy training course. Picademy at PyConUK is a great idea and we’ll sure that it’ll help teachers make contacts with Pythonistas! The second event that weekend is Mozilla’s Festival, known as MozFest (www.mozillafestival.org). MozFest is three days of talks, workshops and demonstrations that centre…

I greatly enjoyed reading Joanna and Nancy Mellor’s letter concerning the lack of female contributors. As a regular contributor to the magazine, I’d like to share my thoughts. As Neil rightly points out, articles are mostly submitted by male freelancers who pitch ideas to the editor. There is no deliberate exclusion of women and, indeed, several of the Linux-related magazines I write for have female editors. This is particularly true (and surprising) in my specialist field of cybersecurity as, in theory, there’s nothing to stop a woman teaching herself to code privacy-related programs. She needn’t even reveal her gender if she wishes, yet the field is almost entirely male. This said, the most secure OS I have ever seen to date is Qubes, the brainchild of Joanna Rutkowska. At a…

AMD is aware that not everyone needs 16 cores, and most games won’t make effective use of more than eight. Some legacy titles even suffer when so many cores are presented to them. So ThreadRipper offers two modes of operation: Creator (the default) and Game Mode. In gaming mode half the cores/ threads are disabled (PCIe lanes et al remain open for business) and the CPU is forced into nonuniform memory architecture (NUMA) mode, which means it favours memory physically closer to the die requesting it, reducing latency. The Zen microarchitecture supports up to eight channels of memory, although the previous Ryzens only enabled dual-channel configurations. With ThreadRipper this is boosted to quad-channel, and the potential latency arises because each die is only directly connected to two channels. Note that,…

If you aren’t averse to making use of CLI options then you can use cryptsetupto create encrypted volumes based on the dm-crypt kernel module. Then there’s tcplay, which is a feature-rich BSD-licensed implementation of TrueCrypt. Another popular encryption utility that is able to carry out stacked filesystem encryption such as EncFS is eCryptfs, which operates at the kernel level. You can also use gpg directly from the CLI to take advantage of its symmetric encryption functionality. Moving over to graphical alternatives, there’s some encryption functionality built into Gnome’s default file manager, which is called Files. The protection is rolled into the Compression dialog box. Then there’s CipherShed, which is another alternative to TrueCryptbut the project shows no signs of active development. Finally, there’s CryptKeeper, which has been dropped from the…

Many routers and IoT devices support WPS, which is supposedly a quick and easy way to connect to devices. In practice it’s a security nightmare because connections are only secured by an eight-digit PIN. And the default PINS for certain devices can be found online! If at all possible, try to persuade the network owner to disable WPS altogether. If this isn’t possible (some routers don’t support disabling WPS) you can at least see how easy they are to bruteforce using Reaver. Open the terminal in Kali and run apt-get install reaver to get started. If you haven’t done so already place your wireless card into monitoring mode with airmon-ng start <interface> . Next run wash -i <interface> to view all devices in range which support WPS. Next, run the…

Once you’ve completed installing Pi-holeon the Raspberry Pi, you need to configure your various devices to use it as a DNS server. By far the most straightforward way to do this is to simply change the DNS settings on your router. This means all devices that connect to it will benefit from the Pi-hole’s adblocking features as well as logging all queries. If your router supports this feature, enter the Pi-hole’s IP address under the first DNS server, leaving the second blank. If your router doesn’t make it possible for you to change your IP address then you may be able to change the DNS settings on individual devices. For machines running Microsoft Windows follow the steps at https://support.microsoft.com/en-us/help/15089/windows-change-tcp-ip-settings to change your DNS settings to the Pi-hole’s IP address. For…

If you’re deadly serious about monitoring all connection attempts to your network, the program kippo-graphis able to aggregate all the data for you in a series of pie charts, bar graphs and maps. You can then study these to your heart’s content. To get started, open the Terminal on your Raspberry Pi or connect via SSH and then install the prerequisites for the software by running sudo apt-get install libapache2-mod-php5 php5-cli php5-common php5-cgi php5-mysql php5-gd . Next, restart the Apache service with sudo /etc/init.d/apache2 restart , then switch to the Apache directory by running cd /var/www/html . Download the latest version of kippo-graph (note that the program is currently at version 1.5.1) by running sudo wget http://bruteforcelab.com/wp-content/uploads/kippo-graph-1.5.1.tar. gz and then extract it with sudo tar zxvf kippograph-1.5.1.tar.gz –no-same-permissions . Rename…

“The Plasma desktop is one of the most advanced in the world, and one of the most popular” About 21 years ago Matthias Ettrich announced his plans for the Kool Desktop Environment: “a GUI for endusers.” He recognised that there was much work to do, and initially sought between 20 and 30 developers to get the project underway. Using an exciting new toolkit called Qt, he saw an opportunity to bring some uniformity to the hodge-podge of toolkits and homespun solutions used by applications hitherto. One year later KDE Beta 1 was released, and the rest, as they say, happened. Active KDE contributors now number around 1,800 and the KDE codebase is made up of over six million lines of code. Today, criticism of the Linux desktop is commonplace (fragmentation,…

The Raspberry Pi Foundation has announced it’s expanding Code Club to reach secondary school ages up to 13. This widens the original target age range of Code Club, which was from 9 to 11. To accommodate the broader range, new projects are available and Code Club will continue to create more resources to build on the support offered to this age group. Before the announcement a pilot group of 50 UK secondary schools were enlisted back in May to discover how support for them could best be implemented and how Code Club could work for children aged 12 and 13. The expanded age range helps Code Club respond to the huge demand and currently one in five UK state-sector secondary schools have registered with the programme and almost all 600…

Bootstrap has been with us for a few years now. It was originally created by one of the developers at Twitter as an internal framework and style guide for internal tooling. After being heavily developed thanks to a hack week, the project went from its internal name Twitter Blueprint to Bootstrap. It’s a responsive, mobile first framework that concentrates on providing a consistent experience no matter what device. In our project we used Bootstrap to write the HTML that made up the interface for our controller. Rather than have either locally written or stored CSS to decorate our project, we used an absolute link to the centrally stored Bootstrap Content Delivery Network (CDN), which is updated by the team. This means that we get the latest version every time the…

Our expert Mats Tage Axelsson After years of fiddling with Linux, Mats has moved on to educate others on how to screw up and recover all parts of your systems. Linux users often argue with users of other operating systems about how brilliant Linux is. Yet one thing that’s always been hard to defend is how tricky it is to download your favourite application directly from the developer’s website and run it. Usually, it’s a deliberate choice to have a central repository with well-tested and secure software. However, for desktop applications, users prefer to find the developer’s website and download from there. Until lately, you could only choose to use a distribution or compile your own. Most regular users won’t compile their software packages. For the developers, maintaining a package…

Our expert Mats Tage Axelsson Mats has spent decades making his computers run Linux. The first was a laptop from IBM back when they were still making them. Back in the early days of Linux, we measured RAM in megabytes. Under those conditions, you could only run a few applications before you ran out. A swap partition was necessary to keep the system running. However, new computers won’t run out of memory, so what’s the point of having swap space at all? The answer is that it’s a good idea to have some swap space for the few occasions you do run out of memory. Ubuntu uses a swap file by default instead of a partition by default. The recommendation for a swap file is either two per cent of…

Our expert Adam Oxford Adam has been using Linux for semi-professional photography for about 10 years. The guys in these shots are from rhino protection team, www.pittrack.co.za. Gnome’s default photography tools are a disaster. The ageing Shotwellis okay, but inclined to hang if you ask it to deal with more than a couple of year’s archives, and the new Photos has a mind of its own when it comes to building a navigable archive. Gnome users who are serious about their photography can draw upon a hotchpotch of decent tools, but nothing comes close to the joy that’s expressed by their KDE-preferring peers who use digiKam. digiKamis unique not just in the Linux world, but pretty much in all of computing for its comprehensive approach to photo management. Some software…

Virtual routing and forwarding (VRF for short), isn’t entirely as it sounds. VRFs resolve the issue of both wanting the benefits of L3 switching, without needing to worry about potential IP conflicts over the network. This is even more useful than it first appears, because it removes the limit of only having approximately 18 million private IPv4 addresses, which is essential when designing large cloud computing networks. Furthermore, it makes possible the additional option of carrying foreign L3 traffic from clients without needing to encapsulate it in an overlay protocol. VRFs are a staple of carrier networks, ISPs, clouds and enterprise networks. They simplify network designs, and reduce FIB size and network latency. Effectively, VRFs are simply a way to divide a switch’s RIB table between separate namespaces, providing a…

Because Dockerdevelopment is pretty rapid, distribution repos struggle to keep up and indeed, most distros have given up trying. But don’t worry, there’s no need to build it from source every time there’s a new release. Dockermaintain repositories for Ubuntu LTSes (14.04, 16.04) as well as the latest 17.04. Note that Docker isn’t available for 32-bit machines. You probably will have these packages already, but it doesn’t hurt to be sure: Next we add the DockerGPG key: Now you need to verify the key’s fingerprint. It should end in 0EBF CD88 , if it doesn’t then either something sinister is afoot (no need to be so dramatic – Ed) or a new key has been issued since we wrote this article. Check the official docs either way. Now we can…

Kotlin supports basic data types such as integers, floats, strings and doubles using the Int, Float, String and Double keywords, respectively. Moreover, Kotlin supports arrays with the help of the arrayOf() function. So, in order to create an array of integers named myInts, you should employ the following Kotlin statement: Additionally, Kotlin enables you to create arrays using a function that’s used for generating each element of the array: Kotlin offers its own array classes for the primitive types. As a result, we have ByteArray, CharArray, ShortArray, LongArray, IntArray, BooleanArray, DoubleArray and FloatArray. Worth mentioning is the Unit type that’s used in the section of this tutorial, which talks about functions. The Unit type is equivalent to the void type that can be found in C and Java programming languages.…

We’ve been lucky enough to work with some early thinkers working on bots. Like every new digital thing, thinking about bots requires thinking about how it’ll be used. Not all bots are the same. Plan carefully what information you really need from the user and how your bot will come across. Will it be serious or playful? Will it guess if the user isn’t sure or be strict about filling the slots? Does the bot need to hand off to another platform if things get too complex? Thinking about bots as having a personality helps a lot, since the user will be interacting with it as they would interact with a human through chat. This means you limit what you promise to the user and make it clear upfront what…

SparkyLinux, one of this month’s distros, offers a customised desktop. It enables you to see what else is possible, but there’s no need to change distros to obtain a better desktop environment. Most distros tend to come with a single desktop. Yet that’s only a starting point, not the final destination. With Linux, just about everything can be changed. Most aspects of your desktop can be tweaked: wallpaper, icons, fonts and much more. Most of this can be done from the standard settings program, while other changes may need you to install a tweak tool first. Or you can download and install themes for a complete desktop makeover. If that’s not enough, there are plenty of other desktop environments to choose: ranging from the full-featured GNOME and KDE to the…

Security doesn’t have to be all doom and gloom. Monitoring, protecting and defending your networks can be fun… if you take the right approach. Part of making it fun is – love it or loathe it, there’s no denying it – the Raspberry Pi, which enables anyone to undertake a host of real-world complex projects for very little cost. The support this device now wields in the form of industry-leading names such as Kali Linux, Debian, Ubuntu and Fedora, means that this tiny board can be put to any use you can think of. Helping to protect your networks this issue, we’re creating a Raspberry Pi honeypot that you can deploy on any network to lure and ensnare unwitting hackers. To block malware we’ll cover Pi-hole, now on version 3,…

While we always want to support our favourite websites, it’s often essential to run an ad-blocker in your browser for a safer and more enjoyable online experience. Many websites don’t want to appear on any filter lists, but one domain is sneakily removing itself from those lists – something that could pose serious problems for adblocking in the future. It emerged that a commit had been added by a Github account to the popular EasyList filter list, that removed the functionalclam.com domain – which belongs to an ad server – with the comment that it was “Removed due to DMCA takedown request”. The original DMCA (Digital Millennium Copyright Act) notice can be read at http://bit.ly/2vPtdq5. It threatens a DMCA takedown unless functionalclam.com is removed from the list and “not replace[d]…

KAOS 2017.09 The latest snapshot for the Linux distro that focuses on providing sleek and user-friendly KDE and Qt-based software, is now available to download. KaOS 2017.09 comes with a hardened Linux kernel with address space layout randomization (ASLR) and Nomad, a Qt5-based firewall application, as well as the Kooka scanning program. To find out more, visit the KaOS 2017.09 release announcement over at https://kaosx.us/news/2017/kaos09. REACTOS 0.4.6 If you want an open source operating system alternative to Windows, offering binary compatibility, then check out ReactOS. The latest version offers, as the release announcement states, “A major step towards real hardware support.” This is great news for anyone who’s been looking to make the switch from Windows to ReactOS. Other updates include dual-booting issues being resolved, safer partition management and other…

Hack Manchester The 24-hour party people of Manchester are back for another massive hack! Hack Manchester is, as you’ve no doubt guessed, a 24-hour hack session in which teams work to solve a challenge or problem set by the hosts. The event takes place in Manchester’s Museum of Science and Industry on 28-29 October, and is sure to generate great ideas from the many coders and hackers around the UK. Who knows, perhaps Hack Manchester will solve a few of the real-world problems that we all face? You can find out more and secure your tickets by visiting www.hac100.com/event/hackmcr-17. #gashack Here’s something new and a little different. Anesthetists aren’t something that we’d normally cover in LXF, but when they want to hack technology to help provide better services to patients…

The primary source of usage information for EncFS is in the form of basic man pages. However, you’ll also find detailed tutorials littered across the web. AES Cryptis a little better in that the project’s website has basic usage information for both the graphical and the CLI versions of the program. There’s also a link to download the more detailed User Guide in PDF format. KGpghas a detailed user manual and you’ll also find some tips and tricks in its page on the KDE UserBase wiki. You can ask for help on the KDE Community forums as well as on the kde-utils IRC channel. You can also post version-specific queries in your distribution’s support infrastructure. zuluCrypt’s help infrastructure covers all the basics. The Help menu informs users about the importance…

“Wardrivers no longer require a team of men in a white van to break into wireless networks” Your Raspberry Pi can be used as much more than a hobbyist’s computer. As a separate machine, you can employ it to improve the security of your home or office network. Over the following pages, you’ll learn how to transform your Pi into a wireless attack platform using the penetration OS Kali, capable of hacking networks. The Pi can also function as a buffer between your computer and potential malware. For this reason, you’ll also discover how to use it as an ad-blocking DNS server with Pi-hole, and a sanitiser for removing harmful files from USB sticks before you insert them into your PC. More experienced users may also enjoy our guide on…

1 Install Kali Download the ARM image for the Pi from www.offensive-security.com/kali-linux-arm-images. Navigate to your downloads folder with cd Downloads . Insert your microSD card, make sure it isn’t mounted. Next use dd to write the image: sudo dd bs=4M if=kali-2017.01-rpi2.img of=/dev/sdb status=progress . 2 Set up Kali and install Kismet Insert the microSD card and power the Pi. Once the login screen boots, use the username root and the password toor. Choose Use default config to display the desktop. Click the network icon at the top right to connect to your usual Wi-Fi network. Next, open Terminal. Run apt-get update and then apt-get install kismet . 3 Configure Kismet Use Tab and return to select OK on the root warnings, then select No when asked about setuid root. Choose…

1 Run the Pi-hole installer Open Terminal on your Pi or connect via SSH then run wget -O basic-install.sh https://install.Pi-hole.net . Next run sudo bash basic-install.sh to launch the installer. The program will automatically check for installed packages and ask you to confirm you want to install a network wide blocker. Press Return to confirm, then once again on the next screen. 2 Edit network settings The latest version of Pi-hole can use your Raspberry Pi’s current IP and Gateway address to assign itself a static IP. Use the space to select your network interface – for example, Ethernet – then choose your upstream DNS provider, such as OpenDNS. The installer will ask if you wish to keep your network settings for the Pi-hole’s IP address. Select Yes. 3 Configure…

In brief... A self-contained kit for all models of Raspberry Pi that offers an introduction to RFID and how it can be used to trigger events. As well as the components to cover six projects there’s a well-written guidebook that covers the accompanying Python 3 library, and explains how the kit can be used after the projects have been completed. For new users, the sheer volume of projects and components is bewildering. Where do you start when you know nothing about electronics or the Raspberry Pi? Well, typically you purchase a kit from one of the many businesses that have popped up to support the Pi community. Simon Monk, author and electronics tinkerer, has a range of Monk Makes kits. The latest is an RFID card kit for all models…

Our expert Nate Drake Nate used to top up his income by offering a file recovery service using scalpel. His first customer was a burlesque dancer. It didn’t end well… Secret Agent, Captain William “BJ” Joseph Blazkowicz’s commendable efforts to halt the Nazi war machine come to a crashing halt at the start of id software’s Wolfenstein 3D. Having successfully thwarted an evil scientist’s plans to create a race of mutant-Nazi hybrids, BJ has been captured and consigned to the dungeons of the Nazi stronghold Castle Wolfenstein. After quickly overpowering a hapless guard, you must now navigate BJ through the six episodes of the game, consisting of ten levels each, shooting evil henchmen and dogs while collecting looted treasure on the way. While using Nazis as bad guys is nothing…

Our expert Shashank Sharma is a trial lawyer in Delhi and avid Arch Linux user. He’s always on the hunt for geeky memorabilia. Features like history expansion, tab-complete and reverse lookup make working with Bash easy and fun. Yet no amount of tab-completion can help you when you frequently have to navigate between deep-nested directories. While it wouldn’t be a bother if you had to access these directories only once or twice, if you have to concurrently work on multiple directory trees, then having several instances of the terminal application open isn’t a practical solution, either. Dirbenables you to create bookmarks to nested directories that you routinely access, and then navigate to them with only a few key strokes, instead of typing in the complete path every time. The tool…

If you want to build a package, either your own or a favourite application, then you can use a build service. An online build services is a good way to save yourself from weighing your system down with compiling jobs. Compiling code is, in itself, not particularly heavy on the system, but there are other advantages of using a build service. For instance, you can set it up so that the system compiles the code as soon as it’s updated. You then have the option to have the application updated on each nightly build. The latest addition to this group is Open Build Service, from SUSE. This service is built to manage the OpenSUSE distribution in different forms, but it can also use repositories, such as git, to build AppImages.…

Systemd-swapis a tool that manages how you use zswap or zram. zswap compresses data that applications don’t use and places it into a cache. The kernel then moves the data to the hard disk, and in most cases this speeds up the swap operation. The systemd-swap utility can be used to create zram instead, which creates a virtual disk in the computer’s memory, to minimise the number of swap operations. Both methods require memory space and so when zswap uses less memory, zram will make use of that memory to stop the swap process from occurring. Essentially, you need to choose one of the two approaches. To install the tool, go to https://github.com/Nefelim4ag/systemd-swap and find the git address and download: Even though systemd-swapis outside of the standard distribution packages, the…

You can stitch multiple photos together to make a panorama or high dynamic range (HDR) image without leaving digiKam. You will, however, need to install the Hugin plugin first. KDE will direct you to the Hugin website (www.hugin.sourceforge.net) to do this, but chances are that you can grab it from your distro repository using sudo apt install hugin or equivalent. To create an HDR image, you’ll need access to a bracketed photograph. This just means that three identical images have been taken at different exposures: the one in the middle is the right exposure and the others are under- and over-exposed brackets. Most modern cameras have a setting that will enable you to do this automatically. In digiKam, you can combine these three images into one HDR image using the…

Our expert Tim Armstrong is the network architect at Nerdalize. He designs and implements datacentre and ISP networks. He’s a real control freak when it all comes to Bits. The rise of open network switches and Software Defined Networking (SDN) has begun a paradigm shift in datacentres, and with a global shortage of network engineers now is the time to get on the bandwagon. Deep in the heart of both the Linux kernel team and the engineering department at Mellanox, engineers have been working hard to bring the biggest change to Linux networking since Intel opened the source code for the e1000 driver. And just like that driver changed the face of Linux networking 10 years ago, SwitchDev does it again. It embodies the beginning to true SDN to the…

When you first enter the networking world, Layer 3 switching can seem too complicated for its own good. Introducing segmentation across the network and increasing overall complexity, with additional protocols required to handle the distribution of routing information just so two or more switches can exchange traffic… this all makes Layer 2 networking child’s play by comparison! Yet this additional complexity brings more flexibility. It enables loops and multiple paths through the network to be fully utilised, thereby increasing throughput and redundancy while decreasing latency. There’s also the possibility of using protocols such as OSPF to further optimise traffic flow through the network. A common example of Layer 3 network architecture’s superiority to Layer 2 network architecture is the implementation of a Clos network. This is a type of Full-Mesh…

If you extend this tutorial and develop fully featured websites in your containers, then you’ll want to keep an eye on how much resources each container is using. You could do this by logging into each container and parsing output from ps or other traditional commands, but that seems painful. You could also modify the image to include Munin or Awstats, which would give access to all kinds of information via a web page. But it’s nice to keep our containers simple. Running a Munin node, say, would require setting up an RRD database, and generating a lot of data, which inside the container could cause more problems than it solves. You can get some rudimentary statistics with a simple: This will show you CPU, memory, network I/O and block…

Kotlin can achieve many more things with function because Kotlin is also a functional programming language. Functional programming is a programming paradigm where functions can also be used as variables, arguments and return values of other functions. Put simply, functional programming considers functions as first-class citizens. Kotlin is also an object-oriented programming language. Essentially, everything in Kotlin is an object! Additionally, Kotlin has complete support for encapsulation, polymorphism and inheritance. The following Kotlin code shows the definition of a simple class using the class keyword: The presented class, which is called myClass, contains two properties, called s1 and s2. However, as you’ll learn in a forthcoming tutorial myClass is far from complete! Please note that methods in classes, myClass has no methods at the moment, and can be private, which…

We’ve tried Lex on a few projects. For those that follow the question-answer or order-response format it works extremely well, and not having to worry about the natural language processing can leap-frog you into a production bot in hours. However, this model doesn’t always work, for example when streaming the firehose of all messages from a channel, or if the bot is going to start the conversation then Lex doesn’t quite do everything we need. We’ve found that combining Lex with custom integration gives us the flexibility of the custom with the NLP power of Lex. There are a lot of tools for building bots, but they often suffer from limiting what you can do by, oddly enough, enabling you to deploy to a range of platforms. Another point to…

System tools Essentials Checkinstall Install tarballs with your package manager. Coreutils The basic utilities that should exist on every operating system. HardInfo A system benchmarking tool. Kernel Source code for the latest stable kernel release, should you need it. Memtest86+ Check for faulty memory. Plop A simple manager for booting OSes, from CD, DVD and USB. RawWrite Create boot floppy disks under MS-DOS in Windows. Smart Boot Manager An OS-agnostic manager with an easy-to-use interface. WvDial Connect with a dial-up modem. Reading matter Bookshelf Advanced Bash-Scripting Guide Go further with shell scripting. Bash Guide for Beginners Get to grips with Bash scripting. Bourne Shell Scripting Guide Get started with shell scripting. The Cathedral and the Bazaar Eric S Raymond’s classic text explaining the advantages of open development. The Debian Administrator’s…

SUSE has reaffirmed its support for the Btrfs file system (based on the copy-on-write principle), of which it’s the biggest contributor, with it remaining the default filesystem for SUSE Linux Enterprise. As a blog post (www.suse.com/communities/blog/butter-bei-die-fische) written by Matthias Eckermann, director product management of SUSE Linux Enterprise, explains, SUSE’s investment in Btrfs has produced a number of features and innovations that are now essential to the distro – and of course, moving to a new filesystem for enterprise users would be a huge undertaking. Google has announced the launch of Chrome Enterprise, a version of Chrome OS designed for enterprise users. With Chromebooks becoming so popular among business and academic users, we feel this is a smart move. Chrome Enterprise, which costs $50 a year per device, comes with a…

“Command substitution enables a command to include the output of another command. For example, we want the symbol THIS_HOST to hold the host name of the system, using the hostname command. There are two straightforward ways of assigning this to a symbol. The older, deprecated way is to enclose the command in backticks: $ THIS_HOST=`hostname` This is still in common use, but it has a number of disadvantages: it’s too easy to misinterpret and nesting substitutions is very challenging. The preferred modern syntax is to wrap the substituted command in a $(...) construction. Our host name example now becomes: $ THIS_HOST=$(hostname) Nesting is now simple. Take assigning the time since a file was last modified, in seconds to the symbol’s age – let’s use FILE to hold the path of…

Old converters As a member of an occupational pensioners’ group, I receive a monthly magazine. It contains a regular Q&A column, where readers can ask for IT advice. But guess what? All the readers’ problems are with various Microsoft products – nothing at all about Linux. So I sent an email to the column writer, asking him why this was the case, and suggesting that he tell readers to ditch Microsoft and install a Linux distro instead. I finished my email by telling him that I experienced IT bliss (no, not the dreaded XP wallpaper) after I installed Ubuntu a couple of years ago. I wonder if my contribution will appear in print? Pete Barrett, Northumberland Neil says: Let’s face it, the reason why everyone is writing in with Windows…

AES Crypt encrypts individual files, so there’s a concept of volumes. Once you’ve linked a.aes file with AES Crypt you can double-click it in the file manager to decrypt it. Due to KGpg’s architecture there’s no concept of mounting volumes. To mount an encrypted volume, in all other programs, you supply a password and/or keyfile. Once mounted, an encrypted volume behaves like any other disk. The biggest advantage with EncFS is that it can be used to protect existing filesystems without block device access, such as Samba shares or cloud storage folders. It also enables offline file-based backups of encrypted files. VeraCryptcan mount volumes via its graphical interface as well as from the CLI. While mounting you can optionally mount volumes as read-only and manually specify their mountpoint zuluCryptstands out…

Wardrivers sometimes employ long-range antennas to both access and exploit Wi-Fi networks from a great distance. The NextG TurboTenna (around £70) can detect networks from hundreds of feet away. It’s popular with campers to make use of free Wi-Fi hotspots! If you’re handy with a soldering iron, consider building your own cantenna. This involves finding a Wi-Fi USB dongle with a detachable antenna and replacing it with one you’ve made yourself using a soup can or similar. You’ll also need an N-male to RP-SMAmale cable, a female N-connector for the can and some 12-gauge copper for the wire element. The dimensions of the can (ideally 3-4 inches by 5) and length of the element are crucial. You can find a calculator here to get started (www.changpuak.ch/electronics/ cantenna.php). You can also view…

“A community effort to bring professional-quality OCR to Linux” OCR software gImageReader Version: 3.2.3 Web: https://github.com/manisandro Accounting, formal office paperwork, library services and, of course, maintaining your own digital archive of historic documents and publications – this is just a short list of applications where optical character recognition (OCR) is welcome. The idea of extracting text from a scanned bitmap image became popular with the rise of home flatbed scanners in the 1990s (ancient times in computing terms), particularly thanks to the commercial Abbyy Finereadersoftware. In Linux, we have an analogue to Finereader, known as Tesseract. This is a community effort to bring professional-quality OCR to Linux, and we must admit, it works just fine. The hero of this review is a graphical front-end to Tesseract, which allows everyone to…

Making random things has always been in my nature, from various Heath Robinson-type machines in my youth to lab mash-ups at university. My parents owned a BBC Model B, and I spent my Saturdays typing in lines of code to make my own games. Skip forward a few years where I dabbled in ticket fraud analysis, learned to fly, and qualified as a maths teacher. I later went on to teach physics, science and art, using zombie movies and race cars, and then ended up in my spiritual home, operating the lasers at Pimoroni. This opened me up to a whole new world of tinkering, and before I knew it I was attending maker events, and meeting a wonderful bunch of people. The Raspberry Pi has enabled me to bring…

Our expert Les Pounder works with organisations such as Raspberry Pi Foundation and micro:bit Foundation to promote maker skills. His blog is over at bigl.es. You need Any Pi A breadboard One LED 220 Ohm resistor (RED-RED-BROWN-GOLD) Five male-to-female Dupont connectors A DC motor An L298N motor controller 4x AA battery pack and batteries Code: https://github.com/lesp/LXF229-Flask/archive/ master.zip Flask is a powerful web server framework for Python and we’re going to use it to control devices connected to a Raspberry Pi via the GPIO Zero library. By turning on an LED using a button on a web page, we introduce how that can be scaled up to do anything with Python and a Raspberry Pi. We also introduce the Bootstrap HTML framework, as used by Twitter, and use it to create a…

If you install the Steam version of Wolfenstein 3D for Windows, navigate to C:\Program Files (x86)\Steam\steamapps\common\ Wolfenstein 3D\base and copy all nine files with the extension .wl6 on to a USB stick, then insert it into the Pi. The files and extensions must all be in lower case to be compatible. Open Terminal and navigate to the USB stick, for example cd /media/pi/USB1 . Convert the files to lower case with for i in $(find . -type f -name “*[A-Z]*"); do mv “$i” “$(echo $i | tr A-Z a-z)”; done . Finally move them to the correct folder with mv *.wl6 /home/pi/Chocolate-Wolfenstein-3D . Next, run the command sudo nano /home/pi/Chocolate-Wolfenstein-3D/version.h . This file determines which version of Wolfenstein you want to compile. Find the section marked /* Defines used for…

Bookmarks that have been created with dirbare unique to each user, because such bookmarks are stored in the ~/.DirB directory. This directory contains a corresponding file for all the user-created bookmarks and each of these files contains a single command. The file for the 2up bookmark that we created contains the following line: As you can see, the cat command displays the content of the 2up file, which is the $CD “../../” command. The shell variable $CD is set by the g command to cd and the quoted variable is expanded by Bash whenever the bookmark is invoked. Essentially, the command g 2up is translated into cd ../../ . You can also refer to the DirB.sh script file for more usage examples of each of the dirb commands. The DirB.sh…

We briefly mentioned Zeroinstall elsewhere in this article, but it’s an interesting project and is worth a little more of your time. To install a program with zeroinstall, you use a public web address where the publisher has put the software. When you run the GUI, you’ll find that there’s no ‘install’ option. This is because packages run from a single directory. Similar to snap, zeroinstall will place all files you need in one folder. The vital difference is that the cache is under your user directory, usually with your permissions in place. Since you’re the only one with permission to run these files, another user on the system can’t use the application and will be forced to download its own version. In your home computer, this won’t be an…

Tuxonice is an alternative method of suspending and hibernating your system. It requires a patch to the mainstream kernel, but there are packages available that will do this for you. For Ubuntu, you have a PPA at https://launchpad.net/~tuxonice. Note that installing the package is simple, but making it suspend to a file is a little trickier, we’ve found. One reason to use Tuxonice instead of the standard package is that the former doesn’t clear the cache when suspending. The effect is that returning from hibernation with Tuxonice will usually make the system feel responsive faster than uswsusp, which dumps the cache when hibernating. There are also many other features available, such as power management and improved ACPI support, so why not give it a try.…

One of the standout features of digiKamis the Batch Editor. As its name suggests, it enables you to perform the same edits to multiple pictures as a group. While many other batch process tools exist for renaming or resizing photos, digiKam’s editor makes it possible to perform any edits that you can apply to a single photo to a group of images. Either select a group of pics in the browser and open up the Batch Editor window, or drag-and-drop files into the left hand pane of the editor. Now you can build up a process by dragging tools from the Control Panel in the bottom right to the Assigned Tools space in the middle. In the top right pane, add tool settings such as the new size, metadata, effects…

While it’s becoming increasingly less relevant, with the addition of overlay protocols, the OSI model is still the most prevalent method for describing the network stack The OSI model classifies the network into seven layers, the most relevant of which are: Frequently, you’ll see network engineers shorten the layer names such as L2 or L3, just to save themselves a bit of time. Sometimes however, we need to use protocols that don’t fit neatly into this model. This results in the use of terms like Layer 2.5 or Layer 3.5 to describe protocols such as MPLS and GRE tunnels, respectively. Furthermore, there’s a common consensus that layers 5 and 6 don’t really exist anymore. Coupling this with the rise of SDN and Overlay technologies is leading many to pronounce the…

Our expert Jonni Bidwell loves to dabble with Docker. The number of times he’s wiped out his whole system has been vastly decreased since embracing the new technology We’ve covered setting up webservers like Apache (see LXF197) and Nginx (pronounced engine-x, see LXF222) before. It’s really not that hard and it’s edifying to do on your own infrastructure, sidestepping the usual template-driven webhosts. But once your friends see what you’ve done they’ll want you to host their website, and their friends websites, and soon you’ll be the web hosting king. Either that or you’ll have no friends left on account of none of them knew what they wanted and you told them to go bother some other chump. Or maybe neither, but if you do find yourself hosting multiple websites…

Our expert Mihalis Tsoukalos is a UNIX administrator, a programmer, a DBA and a mathematician who enjoys writing articles and learning new things in life. This is an introductory tutorial to the Kotlin programming language. After reading this article you’ll be able to install Kotlin, and know how to execute Kotlin code and understand the structure of Kotlin programs. However, because this is the first tutorial in the Kotlin series, it won’t go into too much depth. Forthcoming tutorials will explore many important Kotlin topics including Kotlin data types as well as object-oriented programming, systems programming and web development, so make sure that you understand the concepts presented in this month’s tutorial. The best way to take advantage of this advice revealed here is to try to develop your own…

Our expert Dan Frost Dan works at Cambridge Assessment, experimenting with technology in education. He’s a writer and explorer of ideas and technologies. He’s often found on Twitter (@danfrost) dismissing new fads in computing. Until he champions them. Bots have a varied presence online, from Facebook messenger to websites, the Quartz news app and on Slack. Done well, they’re helpful, can save you time and glue together existing data and infrastructure. However, building a bot can be fiddly. Thankfully, Amazon Web Services (AWS) released Lex, which is the natural language processing engine and bot system behind Alexa. It enables you to build and deploy a bot in very few lines of code. In fact, once you have Lex wired up to your chat platform iterating and adding features is extremely…

Android apps on Linux ChromeOS now runs Android apps and so can you! We bring Android apps to your Linux desktop. Engineering Linux A professional engineer tries to switch to Linux full-time. You won’t believe what happens next! Master your email server Time on your hands? Then master your very own email server with web access and more. It’s “easy”! Create 360 VR videos Edit your own 360 degree VR-style videos, in Linux no less. We outline the tools and the software you need. Contents of future issues subject to change – we might be too busy boogying in the LXF disco dungeon.…