Linux User & Developer的No. 195目录

Welcome to the UK and North America’s No.1 Linux and open source magazine. Data and who controls it is a vital issue. This issue we’re covering how to open source the way you store your own or your company’s data (p18). These days, it’s easy enough to let the cloud slurp it all up, but if you want to be in the driving seat, we highlight some excellent network storage distro options. We’ve also taken a look at three of the open source mobile OSes that will be supported by Purism’s Librem 5 phone due early next year (p58). It’s an early look – dev kits go out in September – but it’s exciting to see a diverse range that will be on offer. In the tutorial sections, we’ve some…

It’s safe to say that, unless you’ve been trapped under something heavy in an underground data centre for the last decade, you’ll know that containers and their orchestrators now rule the roost. The fantastic portability of containers for iterating software releases between development, staging and production environments, without worrying about system compatibility issues, is unprecedented. Docker championed the popularity of containers with clever accessibility and excellent features. Within a relatively short space of time the global container explosion happened, and a few years later, here we are. There was – and still is – a problem, however, and it’s far from a trivial one. It’s simply that while everyone agreed containers were great, no one really bothered to check how secure they were. Throwing precious production workloads at a ship-full…

A key aspect of the PeerTube platform is the ability for users to host their own video-sharing server, or what are called ‘instances’, and then sync their instance with others that they find within the federation. PeerTube server instances use a REST API (Express framework), a WebTorrent Tracker and, for seeding a video, WebSeed protocol (HTTP). When a video is uploaded by a user, the REST API creates a torrent file and adds the file to its database. When a user wants to watch the video, the tracker indicates all other users that are watching the video and the HTTP URL for the WebSeed, which enables BitTorrent clients to download torrent pieces from an HTTP source.…

There is a fair amount of confusion abounding on this topic. The problem is that Oracle released the sources to ZFS, but they did it under the CDDL licence. This licence is incompatible with the GPL used by the Linux kernel. The upshot is that it appears to be illegal to distribute a kernel containing ZFS. We say appears to be because opinions are divided, but no one has risked testing this in court. Fortunately, you can install the ZFSonLinux package yourself with no ramifications, which then gives you the ability to set up ZFS filesystems.…

1 Install Gerbera Most distros have Gerbera in their repositories, ready to be installed from the package manager. Note that the latest 1.2 release is quite recent, so you may need to install from source to get that on some distros. See http://docs.gerbera.io/en/latest/compile.html. 2 Create a default configuration If this hasn’t been created, create one with the following commands and then start the service: 3 Open the interface Open http://[YOURNAS]:49152 in a browser to see Gerbera’s interface, where you can add content by selecting directories to share. You can add a directory as is, or you can add it as an autoscan item, in which case any new content will be added automatically. 4 View your content Click the Database link and pick the type of content you want to…

1 Create a repository Create a repository with $ borg init --encryption=none /backup/ dir. This initialises a repository without backing up anything. We have used no encryption here, but you would usually want to use one of the options covered in the documentation. 2 Create a backup $ borg create /backup/dir::first_ backup /home creates a backup of your entire home directory. We are using a local backup directory here, but you can store the backups on a different computer with user@host:/backup/path 3 Later backups Use $ borg create /backup/dir::next_ backup /home for subsequent backups. This is much faster as Borg backs up only changed files; each backup represents the state of the file system at the time of backup, but each file is stored only once. 4 Restore options You…

Recording macros and coding things in Basic and Python isn’t the only way to extend functionality in LibreOffice. You can find a full listing of supported extensions and templates at https://extensions.libreoffice.org. One plug-in that caught our eye was Power Detective. With larger datasets using a lot of different calculations, it can be tricky to determine how one change might affect other parts of the sheet. This plug-in draws arrows from any given cell to any other cells that are dependent on it to complete their functions, ensuring you don’t accidentally miss any parts of the sheet with #REF! as their value before sharing it. Another example would be Calendar for Calc, which provides a visual date picker instead of having to type in date values manually. There’s also a very…

1 A Bug Hunter’s Diary Tobias Klein Published by No Starch Press When it comes to technology, as soon as you have finished writing about something it’s rendered obsolete almost immediately. We should know! Some books may now be quite behind the times and yet others are explicitly written to look that way – like A Bug Hunter’s Diary, an amazing read through the wilds of software security. Here you will learn about the old ways of finding and exploiting bugs. Some of these techniques are still applicable today, although due to newer operating systems and their memory protections, without ROP (Return Oriented Programming), you would irremediably fail. 2 The Hacker Playbook Peter Kim Published independently You should probably have heard of Peter Kim; he’s a well-known professional pen-tester and…

Kyle, thanks for speaking to Linux User & Developer. What’s your role at Purism? I am the Chief Security Officer at Purism and responsible for all things related to security, from internal infrastructure security and hardening PureOS, to the physical security measures on Librem hardware. Much of my current work has been focused on our tamper-evident features, where I have focused on making the tamper-evident boot project Heads work on Librem hardware while making it more accessible overall. Most recently I’ve been working on our new Librem Key USB security token product and integrating it both with PureOS and with Heads. What brought you to the company initially? Before I joined Purism, I had been a long-time supporter of the company that began when I reviewed the very first Librem…

Ubuntu Touch has more options for device installs than KDE Plasma Mobile, but the selection of compatible phones is still limited. If you want to try Ubuntu Touch, use a i386 build of Ubuntu and ‘ubuntu-emulator’, installed using apt from the multiverse repo. After installation use the command ubuntuemulator create --arch=i386 myinstance followed by ubuntu-emulator run myinstance to start.…

Specs CPU Any 64-bit processor Graphics Depends on the desktop you install RAM At least 4GB for an enjoyable experience Storage At least 12GB Licence GPL and others Available from  https://arcolinux.com ArcoLinux has had a busy first year. The distribution/project has gone through two name changes in order to better encapsulate its developers’ ever-growing vision. Unlike most distributions, ArcoLinux is pitched as a platform to learn Linux the Arch way. The lead developer has broken up the Linux learning process into six phases, and the three ArcoLinux distributions are part of those phrases. Interestingly, the final phase of the process is to create your own customised distribution on the mainline Arch install. Of the project’s three releases, the main ArcoLinux release comes with three desktop environments, is chock full of…

Despite its version number, this application has been around for many years and is quite stable. The project identifies itself as a hierarchical note-taking application. You might not find the latest version in the software repositories of your distribution but thankfully installation is straightforward, and the project itself provides a source tarball as well as RPM and DEB packages which you can use to install the tool in a variety of Linux distributions. On first appearance, the tool appears little more than a text editor, but it’s far more useful. Unlike traditional text editors, it supports rich text format, syntax highlighting and spellchecking, and can even export your notes to plain text, PDF or HTML files. The cross-platform tool is available for Windows and Linux and stores all the data…

1 Hub owner: GoogleChromeLabs Project: ndb 6,772 stars 5 contributors ndb is an improved debugging experience for Node.js, enabled by Chrome DevTools 2 Hub owner: browsh-org Project: browsh 5,736 stars 15 contributors A text-based browser, rendering to TTY and browsers 3 Hub owner: faressoft Project: Terminalizer 4,607 stars 4 contributors Records your terminal and generates an animated GIF 4 Hub owner: jesseduffield Project: lazygit 4,454 stars 10 contributors A simple terminal UI for Git commands, written in Go 5 Hub owner: vuejs Project: vue 3,925 stars 189 contributors A progressive JavaScript framework for building UIs 6 Hub owner: dylanbeattie Project: rockstar 3,871 stars 18 contributors A rock ‘n’ roll programming language specification 7 Hub owner: GoogleContainerTools Project: jib 3,695 stars 18 contributors Builds Docker and OCI images for your Java…

The decentralised social networking protocol ActivityPub is appealing because it standardises both the client-to-server and server-to server APIs. The client-to-server protocol is how a user account (whether human, bot or other automated process) can communicate with ActivityPub on a server using many different devices, including a desktop computer, mobile phone or web application. The client-to-server API is used for creating, updating and deleting content. The second interface is a server-to-server federation protocol. This uses an API for delivering notifications and content, so that decentralised websites can share information with each other. ActivityPub uses an email-like inbox and outbox system, and every user is represented by ‘actors’ via the user’s accounts on the servers (see diagram). Every actor has an inbox for getting messages and an outbox for sending messages. User…

1 HP Microserver  www.hp.com These compact boxes have four drive bays plus a DVD connector (which you can use to attach an SSD for the OS). They are reasonably priced most of the time, but watch out for frequent cashback offers for a real bargain. 2 Dell T30  www.dell.com Another frill-free server box, this time in a more traditional tower format. With plenty of drive spaces and lots of RAM, one of these will make a good NAS. 3 Synology DS218+  www.synology.com A typical off-the-shelf NAS. These are easy to set up initially, but you lose out on the flexibility of using a general purpose distro as the base. Ideal for the plug-and-forget brigade.…

While using the command line is often the quickest way to administer a computer, that is mainly true when you know what you are doing, performing tasks that you do often enough to know the commands. There are other times a GUI is easier, as you can browse the options, but how do you run a GUI on a headless server? The answer is, of course, in a web browser – we’ve already done that with Gerbera. The program for this is Webmin (www.webmin.com), which should be in your distro’s repositories, so install it in the usual way and make sure it’s running – it’s started as a service with systemctl. Connect to https://[hostname]:10000 to access Webmin. 1 System Information Webmin keeps you up to date with the NAS’s current…

There are two types of variable in LibreOffice Basic. Global variables are defined inside a module file and can be used by any subroutine or function within it. Local variables can only be used within the subroutine or function it’s declared inside. By convention, people typically use Dim for variables for which they want to declare a type, like so: A common mistake new programmers sometimes make, especially if you’re used to more complex languages such as C++, is to become confused about the difference between subroutines and functions. Both will accept parameters (variables that you provide as inputs), perform operations in a predetermined order and change the value of global variables. The key difference is that a function will output a value for use in a variable, while a…

“venv is preferable to virtualenv because of venv’s significantly lower memory demands” The tremendous breadth of the Python ecosystem is the language’s strongest selling point. But great power can lead to great inertia. Python 3.x broke backward compatibility while introducing badly needed syntactic changes, which library authors were less than keen to accept. Having to reconfigure a system-wide Python installation quickly becomes tedious, and installing specific versions of the interpreter can break some distributions; for example, initialisation scripts can fail due to syntactic differences or library API changes. A way to avoid this is to use virtual environments (venvs), which isolate projects from the system’s Python environment. Libraries installed in a venv don’t interact with the rest of the system, thereby reducing clashes and leading to a more enjoyable programming…

For a product such as the Librem 5, it could be argued that raising the money is the easy part. Many a Kickstarter project has come and gone, scuppered by the realities of producing an actual product. Thankfully, Purism has considerable experience in this area because of its laptop pedigree and thus far, the team are doing a great job of keeping backers updated with regular, extremely detailed updates on its website. These are important not just for those who have funded the project, but for developers too. A recent post locked down a key set of hardware specifications: the EmCraft i.MX 8M processor, a 5.7-inch screen with a resolution of 720×1440 pixels, a SIMcom modem, a Redpine Wi-Fi and Bluetooth module, and an Omnivision OV5640 camera. Frequent updates have…

Should you want to install Linux on your current (Android) device without losing its normal functionality, you have several options. Installing a full Linux distro on your device provides a whole host of functionality, including the ability to turn your phone or tablet into a fully blown LAMP server, providing a way to run your favourite command line tools, or even running a graphical desktop environment – although performance on an Android device is typically not great. Having a full Linux install just waiting to be used if needed is a nice back-up if you need to do something important when you’re out and about without your laptop. If you don’t want to root your Android device, which typically involves unlocking the bootloader, wiping your device and making a number…

The Linux desktop is home to several different IM clients, and many popular Linux distributions feature one in the default installation. BeeBEEP provides all the features of a modern IM client, but is designed to connect you directly with peers on your network. Apart from chat messages, you can also use the tool to share files with other users on the home or work network. The peer-to-peer messenger can automatically detect other BeeBEEP users on the network. It encrypts all chat messages using the AES algorithm, and like any other IM client, you can use the tool to initiate group chats, or limit conversations to a single user. While the interface is straightforward, the tool boasts useful features such as drag-and-drop, so you don’t have to navigate through menus and…

Indian microprocessor builder Shakti has revealed the arrival of its first RISC-V chip, a low-power prototype that could revolutionise mobile computing. At this stage it’s limited to running at 400MHz, but it does successfully boot Linux. An open source initiative from the government-funded Indian Institute of Technology Madras, the Shakti project aims to develop industrial-grade processors using the RISC-V instruction set. Announcing the development on Twitter (“First silicon success on the first tapeout!! Linux boots on Shakti processor, India’s first @risc_v based silicon chip!”), the @ShaktiProcessors account confirmed that the code for the project is open source. RISC-V is an open ISA (Instruction Set Architecture) developed by the University of California, Berkeley, in 2010. As a potential successor to ARM, RISC-V is intended as a low-power, fast and compact CPU.…

The internet was originally decentralised, but today a vast proportion of data flows through a handful of major internet companies. The way these services are controlled, the amount of personal data they harvest and how that data is used – particularly in recent election campaigns – are all serious concerns for many users. But decentralisation is on the rise again. Federated services have always been a popular concept in free and open source circles – the first was probably identi.ca, the open source microblogging platform, launched in 2008 – but in recent years we’ve seen much higher profile and frankly more appealing decentralised services, such as Twitter alternative Mastodon, grow in popularity as the general public has become more aware. Another recent project, PeerTube, smashed its crowdfunding target by over…

Linus Torvalds has announced 4.18-rc8. In his announcement message, Linus noted that a few last-minute worries about some VM (Virtual Memory) instability had combined with a general sense that 4.18 wasn’t quite ready to be final. This resulted in an unusual Release Candidate 8, and a subsequent one-week delay to the merge window for new features scheduled to land in 4.19. All in all, 4.18 had over 12,000 ‘changesets’ (collections of patches), from over 1,600 individual developers. We will have a summary of the new features landing in the upcoming kernel 4.19 in the next issue. Intel Control-flow Enforcement Technology Today’s computer systems are subjected to an ever-increasing barrage of attacks by malicious actors, as well as the efforts of the best security researchers. We have seen this play out…

btrfs is simpler to start with than ZFS as it’s in the kernel; you only need to make sure the btrfs userspace tools are installed. As with ZFS you have an overall file system, like the ZFS pool, and subvolumes similar to ZFS datasets. Create the file system like this: You can use any component device when mounting it, although take note of device nodes possibly changing. A safer option is to give it a file system label with the -L option. Now create a volume with: You can mount this anywhere you like by referring to the subvolume name: The concepts of the two file systems are similar, but ZFS is more mature and has features such as quotas, which btrfs lacks in any meaningful way, and should soon…

1 Install PiVPN Use $ curl -L https://install.pivpn.io | bash to download and run the OpenVPN installer. If you have an unsupported Ubuntu-like distro, like Linux Mint, you can download the script and add your distro to line 99, then run the script with Bash. 2 Set IP address As a server, you need a static IP address. PiVPN will set this when used on a Pi. On any other system, use the distro’s usual network configuration tool to pick a suitable address, which should be on the same subnet but not in the range allocated to DHCP. 3 Set the port The default port for OpenVPN is 194 and there’s no real need to change it, unless you want to run more than one VPN off the same router.…

Your NAS can quickly accumulate a lot of data that is conveniently all in one place – but that also makes it vulnerable, so you need to consider keeping your data safe. The first step may be to use RAID storage to protect against single-disk failure, but what about more extreme situations, or simple user error? Backups are obviously the answer, but what you need to backup varies depending on your setup. Keeping the OS separate, as mentioned earlier, means ensuring this is backed-up regularly is fairly straightforward. As for your data, you need to consider ease of replacement. Video files, such as films you may have have bought online, are relatively easy to re-download; on the other hand, personal photographs or important business files could be impossible to replace.…

LibreOffice Basic has useful debugging tools. Start troubleshooting by hitting F8, then keep pressing it to step through code line by line. Shift+F8 steps over code you don’t need to test this way. If there’s a lot of code you’re happy to skip past, use F9 to add or remove a breakpoint to any line. This means the debugger will halt at that line so you can start stepping through it line by line again. Highlight a variable and press F7 to add a ‘watch’ that shows you how its value changes.…

The basic quanta by which clients can transfer information to a web server is HTTP POST requests. Typically, they are generated by some kind of form, and they’re set up to transfer any kind of data. The enctype field in the HTML <form> tag specifies the encoding type that will be applied to the form data. Typically, the encoding performs some character replacements, such as replacing spaces with + characters. We’re using multipart/ form-data because we do not want to modify the video data in any way.…

AUGUST 2017 Crowdfunding for the Purism Librem 5 kicked off in August 2017. The original goal was to hit $1,500,000, with the now customary stretch goals added if this target was exceeded. JANUARY 2018 After the success of the funding effort, the turn of the year saw a focus on expanding the teams on both the hardware and software sides to enable the project to successfully deliver. JUNE 2018 As 2018 progresses the software build continues in earnest. The first milestone is a software proof-of-concept, to prove the viability of the software approach and bootstrap the main development effort. SEPTEMBER 2018 The Librem 5 developer kit ships in September. A raw PCB that won’t really resemble a phone, the kit will be close enough to the final product’s internal hardware…

If you are considering using KDE Plasma Mobile for the Purism Librem 5, or perhaps you just want to give it a try (particularly if you’re using Plasma on the desktop), you have a couple of options. Aside from running on a Nexus 5X, you can also download pre-built – although not very frequently updated–images for use in QEMU or VirtualBox. While this won’t give you an exact idea of what the OS feels like on a mobile device, it works well enough for you to get the general idea. The experience does highlight that there is still plenty to do before the Librem 5 launches in March 2019 for Plasma to be in a good usable state.…

1 Install a terminal emulator Installation of KBOX is carried out directly on your device, from the command line. The first step is to install a Terminal Emulator application from the Google Play Store, such as Terminal Emulator by Jack Palevich (free). 2 Download the base system installer KBOX can’t be downloaded from the Play Store like other apps, but a full install guide is available from www.kevinboone.net/kbox.html. You’ll need to download the right version for your device, Arm or x36. 3 Prepare installer Launch your terminal emulator, cd to the app data directory (cd /data/data/jackpal.androidterm), copy installer (cat /sdcard/Download/kbox4-install-base-arm > kbox4-install-base) and set permissions (chmod 755 kbox4-install-base). 4 Run and complete the installer Now that everything is prepared, you simply need to run the installer with ./kbox4-install-base. When this…

Judging by Notepad on Windows, and the likes of gedit and Leafpad on Linux distributions, you might believe that text editors are simplistic and bland, with hardly any features of use beyond compiling quick to-do lists. Of course, you can extend many with plug-ins to support additional features such as syntax highlighting, line numbering and so on – but if you want more features, you usually need to switch to a word processor. TEA, however is a contrarian text editor with a starkly different user interface. The tool boasts many unexpected features such as a built-in calendar and image viewer, bulk rename functionality, syntax highlighting, Midnight Commander-style file browser, and much more. Despite being billed as text editor, it supports a number of file formats including ODT and DOCX among…

Available for Linux, Mac and Windows, the latest release of this vastly capable video editor features many minor additions. Unlike some other similar tools, the project prides itself for its support of keyboard shortcuts, and you can engage most of its functions without having to reach for the mouse. You can use the timeline for non-linear video editing of multiple tracks. Thanks to FFmpeg, the tool supports a large variety of audio, video and image formats. The latest release adds support for 4K video, webcam and audio capture, network stream playback, exporting a single frame as an image or a video as an image sequence, and even multi-format timelines – which means you can mix video segments with differing frame rates and resolutions within a single project. Apart from 64-bit…

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