Sommaire pour No. 171 de Linux User & Developer

This issue » Better servers in 24 hours » Remote admin on Ubuntu » Open source AI » Prevent SSH attacks Welcome to the latest issue of Linux User & Developer, the UK and America’s favourite Linux and open source magazine. Servers were once the sole province of corporations and other large organisations. Now you’re much more likely to see one in someone’s home – maybe they’re running their own business with it and it’s dealing with essential files and folders, web access and accounts, or maybe they’re simply using it to serve files around their home network. These days many more of us are doing that, and if you want to get in on the action, then head to p18 where our experts explain everything you need to know…

Micro Focus, the owner of SUSE, has announced the merger between itself and Hewlett Packard Enterprises. The deal, which was in the final completion stages at the time of writing, is said to be worth around $8.8 billion. HPE shareholders will now hold a 50.1 per cent share in the merged company. Due to increased competition in recent times, SUSE has been going through a prolonged rough period, with this large cash injection expected to help steady SUSE and continue its growth into the future. While the merger may be a surprise to some, it certainly seems to be a great idea for both parties. HPE boasts an impressive software portfolio, and despite recent slip ups, SUSE still remains one of the top 10 contributors to the Linux kernel. The…

HIGHEST QUALITY OFF THE SHELF If quality is more important than price, then an off-the-shelf server from a respected vendor such as HP or Dell is likely to be the best option. One of the main reasons for this is after-sales support – if your server goes down with a hardware fault, having a guaranteed on-site warranty can be important. Enterprise-class servers also have impressive offerings around server management, with tools such as HP’s iLO that allow you to work on a server remotely even if its operating system is having problems – something that’s not unheard of on Linux boxes! BEST VALUE BUILD IT YOURSELF As well as pure value, there’s a certain satisfaction that comes from specifying server components yourself and building something that exactly fits your needs.…

When deploying a server at home or in the office, by far the most common use is for file backup and storage. While cloud storage has its place, for performance reasons it just makes sense to have a local copy of data, particularly when it’s large and you might want to manipulate it, the main example being photos. Building a file server – also often referred to as NAS (network-attached storage) – is a great way to start, giving you the ability to expand the functionality later on. Building a file server can also be relatively cheap, as a powerful machine isn’t needed. Choosing your hardware There are two key hardware aspects to a file server: the disks, as you’d expect, and the network connectivity. Start by determining how much…

Resources .NET for ‘any Platform’ dot.net Get Started with ASP.NET Core asp.net/get-started Visual Studio Code code.visualstudio.com Yeoman yeoman.io ASP.NET Core Yeoman Generator bit.ly/2cw2UKx ASP.NET Core MVC programming model docs.asp.net/en/latest/mvc/ Open Weather Map API openweathermap.org ASP.NET  Core is a new modular, lightweight, low memory, cross-platform web development framework. This .NET-based web development framework was developed as an open source GitHub project under the flexible MIT licence and leverages the new cross-platform aspects of .NET Core. With the first release of ASP.NET Core that came in June 2016, Microsoft, together with an engaged developer community, has reinvented ASP.NET into a modular, package-based architecture that includes a cross-platform, high-performance web server. Dependency Injection (or DI) has been woven throughout the new framework and core .NET classes have been placed into many fine-grained packages.…

 One of the biggest problems in the world of computing is the presence of significant others: whenever you are involved in some kind of long-running or interesting task, you can be sure that someone will arrive to distract you. “Hordes of miscreants are waiting to take over poorly secured systems connected to public networks” One nice way to address this problem involves the use of remote access technologies. While VNC and similar graphical access systems exist, this story looks at the most classic of tools known to UNIX administrators. SSH – the name stands for Secure Shell – is an advanced version of the basic Telnet protocol that saw ample use in workstations and even some test equipment. The modus operandi of SSH and Telnet is simple, too: they allow…

After installing Linux Mint 18, you'll need to look for some additional apps. Not so long ago, some of these would have been included, proprietary apps from developers such as Microsoft. But unless it's a browser, email client, or functional office application you actually need, many don't want the pre-installed apps, and with Linux Mint 18 the developers recognised that. Withdrawing the proprietary apps has led to a small problem, however: users will now have to go searching for apps regardless, beyond the bundled browser and various office tools. While on the one hand this allows for the installation of FOSS applications, it also has a downside: what if a long-term Linux Mint user wanted to use the proprietary apps? Whether you want to avoid proprietary software in Mint, or…

What you’ll need • Maplin Robotic Arm • Pimoroni Skywriter • Raspberry Pi 2 or 3 This tutorial combines the Maplin Robotic Arm and Pimoroni’s Skywriter HAT to enable you to take control of the robot with just the touch of your fingertips. The arm can move through three points of articulation and ends in a clamp to give you maximum flexibility with movement. The arm also moves through 120 degrees in the wrist, 300 degrees at the elbow, 180 degrees at the base in the vertical and 270 degrees in the horizontal. It is easy to assemble and is a great beginners’ robot. In this tutorial you will first install the Python modules to enable your Raspberry Pi to interact with the USB port, and then learn how to…

“IPython is a great way to put all of these machines to work” “In a previous article, we looked at how to combine multiple Raspberry Pis together to make a cluster of machines. But how can you make use of this small monster that you have created? Luckily, IPython is a great way to put all of these machines to work, getting some serious work done. IPython started out as an enhanced interface for Python, replacing the usual interactive interface that is available. The initial design involved creating a client/server system for IPython, which quickly allowed for some very interesting functionality. One of these extra capabilities is the ability to run multiple IPython servers that a single IPython client can connect to. You can then connect to these IPython servers…

Do we need another command line text editor? If you’re a power user, totally happy with vi or Emacs, and using them across networks, then the answer is no, but consider this scenario: getting a non-technical user to edit a file on an Ubuntu VPS with nano. Wouldn’t it be great to have a reasonably powerful text editor that ran in the terminal, and used the familiar (CUA-based) common keybindings (Ctrl+S, Ctrl+C, Ctrl+V, Ctrl+Q…)? This alone could justify you installing micro on all new Ubuntu installations you make – its 8.5MB static binary is not going to be a resource problem in most use cases – but there’s more to micro than sensible default key bindings. Mouse and clipboard support are good, too, and configuration – via Lua, or the…

Welcome to the Linux User & Developer DVD. This issue, get the most from Mint. Choose from the Cinnamon or MATE desktop environments for the Ubuntu-based Sarah edition, or load up the Cinnamon environment for the Debian edition, and learn how to configure them like a pro and explore how you can do more with the world’s favourite Linux distro. Featured software: Linux Mint 18 ‘Sarah’ – MATE edition The MATE edition of the Linux Mint desktop boasts all the power of the latest version of Mint combined with the solid, traditional interface of MATE – perfect for increasing your productivity and giving you all-round usability. This distro live boots. Linux Mint 18 ‘Sarah’ – Cinnamon edition For those who like their desktop to have some graphical flair, the Cinnamon…

Drones have become one of the biggest hobbies of 2016, and rightly so. The market for drones is constantly expanding, but up until now there’s been little crossover between drones and the Linux operating system. Canonical’s new partnership with drone manufacturers Parrot looks to change all that. Together the two tech giants have created the S.L.A.M.dunk development kit, aimed at aiding the creation of autonomous and obstacle avoidance drones and robots. The kit is powered by Ubuntu and the Robot Operating System, which allows Linux developers to prototype designs, perform 3D mapping and use on-board sensors for data gathering. Attaching the kit also couldn’t be simpler, as the tiny wing-shaped device attaches to the top of the drone, relaying data almost immediately. It’s believed that as time goes on and…

Top 10 This month Stable releases (15) In development (7) Mint continues to showcase its popularity, as it proves to be head and shoulders above the rest in terms of downloads. However, across the board, downloads are generally down compared to last month. Highlights Mint Mint’s downloads have been bolstered with the launch of the early Mint 18 KDE beta. In its current state, the overall design is gorgeous and it works seamlessly out of the box. Expect figures to grow over the next few months. Zorin Little has come from Zorin in recent times, but downloads still remain steady. Zorin OS 11 remains one of the better beginner distros on the market today. CentOS CentOS has recently received an important kernel security update, which has helped claw back some…

“Linus Torvalds announced Linux 4.8-rc8, the final Release Candidate (RC) prior to the imminent 4.8 kernel release. Typical kernel development cycles have only seven release candidates (preceded by a 2 week merge window at the start of the cycle, during which disruptive new features are taken into the kernel), but it is not without precedent to have more. Usually, Linus will only add an extra RC if he feels that development hasn’t quite featured a point at which he is satisfied things have calmed down enough. Indeed, in his announcement of 4.8-rc8, Linus said as much: “Things actually did start to calm down this week, but I didn’t get the feeling that there was no point in doing one final RC, so here we are”. The release of the final…

If you already have a Linux server running in your home and/or business, what’s the easiest way to upgrade? One of the best things about Linux is that this process is nowhere near as painful as if you are running Windows! If you are upgrading components in an existing Linux server, typically things will ‘just work’ provided they are supported within the Linux release you are using. On the Windows platform, drivers, reactivation and blue screens are often an issue. If you are switching to a completely new box, you can quickly get started on new hardware by cloning the old OS to a new disk. If you have decided to upgrade to a better server, there’s a wealth of tools out there that will help you to benchmark the…

If you have a basic server up and running (or a file server, as discussed previously), one of the first additional requirements you ask of it is likely to be that it functions as a web server. From a hardware perspective, this task is also relatively low-powered, although if you plan to run a database with a lot of data too, RAM and processor requirements may creep up. A web server is useful for servicing both static content and scripts – work through the steps here via a shell to get started with a full LAMP (Linux, Apache, MySQL, PHP) stack. 01 Start with a full distribution Earlier on in this guide, we talked about the benefits of going with a full distribution of Linux from the off rather than…

“Using keys with passphrases is much more secure than passwords, but it becomes much more cumbersome” Resources Linux System Administration Basics bit.ly/2cwvbR6 Linux System Administration and Configuration bit.ly/1N2N1tt Remote Administration bit.ly/2coInnN 11 Awesome Tools for Linux Sys Admins bit.ly/1kMkw2M When experienced Linux professionals need to access other computers for remote administration purposes, they can work from the command line. And it is good to see that there are various Linux commands that will help in scenarios, offering a rich feature set. As we all know, the tools that are associated with the Secure Shell (SSH) service allow remote login and file transfer. But in addition to these, such tools offer encrypted communication that will help us to keep our remote administration work secure. By using a tool such as Virtual…

Initially launched in 2006 and based on Kubuntu, Linux Mint 1.0 ‘Ada’ was soon replaced by the Ubuntu-based Mint 2.0 ‘Barbara’. Linux Mint built each release on top of the previous one, but using the Ubuntu codebase package repositories. This resulted in compatibility between Linux Mint and Ubuntu, rather than the later distro becoming a fork. Just four years later, however, came Linux Mint Debian Edition. Issued on a rolling release based on Debian and without any ties to Ubuntu packages, LMDE 2.0 ‘Betsy’ followed in early 2016, an LTS distribution without the rolling updates. Despite the origins of the two Linux Mint editions, you have the option to be as flexible as you like. LMDE 2.0 comes with a choice of MATE and Cinnamon desktops, for instance, and we've…

Linux Mint 18 comes ready to use, but to squeeze some extra performance out of it, try these tricks. Stop hibernation Power saving is great for batteries, if it is implemented correctly in the BIOS or UEFI. As this is rarely the case, hibernation can be a problem. Ubuntu has it disabled, but Mint does not. Hibernation – in which the session is saved to the HDD – can be disabled in the terminal with Remember to reboot to implement the change. Streamline software installation Mint doesn't install recommended packages by default, but you can change this via Menu>Administration>Synaptic Package Manager, then Settings>Preferences>General. Under Marking Changes, check ‘Consider recommended packages as dependencies’, then Apply and OK. Then, in the terminal enter this: Optimise the Update Manager Linux Mint's cautious update…

As people have worked with writing parallel Python code over time, the painful parts have been identified and people have written packages to try and make these a bit more comfortable to work with. One of these packages that has been gaining in popularity is dask. The real power of dask is its flexibility. It can use many different parallelisation backends, and it also gives methods and objects that build on those used for scientific computations. For example, these new objects can mimic numpy arrays, or pandas data frames. Because of all of this additional functionality, you can select what you want support for when you install dask. For example, if you want everything, you can install it with this command: The back end parallelisation method used by dask is…

“Such a design felt horrible in a joystick in the 1980s, and it feels horrible as you laboriously type with your thumbs on the PocketCHIP” Price CHIP $9, PocketCHIP $69 (plus taxes and shipping), cables extra Website getchip.com Specs Size (CHIP): 62.9mm x 41.3mm x 14.8mm Weight (CHIP): 30g Size (PocketCHIP): 112.5mm x 165.1mm x 26.2mm Weight (PocketCHIP): 267g CPU: 1GHz Single-Core AllWinner R8 ARM Cortex-A7 GPU: ARM Mali RAM: 512MB DDR3 Storage: 4GB eMMC Networking: 802.11b/g/n Wi-Fi (2.4GHz only), Bluetooth 4.0 Connectivity: 1x USB, Analogue TRSS AV, 2x 40-Pin GPIO (1x 25-pin on PocketCHIP) The CHIP is an ultra-compact microcomputer built around the AllWinner R8 system-on-chip (SoC) processor. It’s designed to be affordable yet functional, and runs a customised variant of Debian Linux. Compared with the Raspberry Pi, there…

“A state-of-the-art data centre environment enables Netcetera to offer your business enterprise-level colocation and hosted solutions” Featured host: www.netcetera.co.uk 0800 808 5450 About us Formed in 1996, Netcetera is one of Europe’s leading web hosting service providers, with customers in over 75 countries worldwide. As the premier provider of datacentre colocation, cloud hosting, dedicated servers and managed web hosting services in the UK, Netcetera offers an array of services designed to more effectively manage IT infrastructures. A state-of-the-art data centre environment enables Netcetera to offer your business enterprise-level colocation and hosted solutions. Providing an unmatched value for your budget is the driving force behind our customer and managed infrastructure services. From single server to fully customised data centre suites, we focus on the IT solutions you need. What we offer…

Live boot Insert the disc into your computer and reboot. You will need to make sure that your computer is set up to boot from disc Distros Distros can be live booted so that you can try a new operating system instantly without making permanent changes to your computer FOSS Insert the disc into your computer and double-click on the icon or Launch Disc file to explore the contents Explore Alternatively you can insert and run the disc to explore the interface and content Important information Check this before installing or using the disc For the purpose of this disclaimer statement the phrase ‘this disc’ refers to all software and resources supplied on the disc as well as the physical disc itself. You must agree to the following terms and…

1 OpenShot The reason OpenShot has remained so popular for so long is down to its simplicity. In just a few minutes, you can have cut your video on the timeline, fully rendered it and then exported it. Of course, there are plenty of advanced options also included, but it’s the basics that it really excels at. 2 Pitivi Pitivi is one of the few video editing suites written in Python, but that doesn’t detract from its suite of features. It’s a great choice for those seeking an easy way to manage multiple video files simultaneously in one place. 3 Lightworks Perhaps the best thing about Lightworks is that there’s both an RPM and deb download available for it, something not usually found in most video editing suites. Options are…

If you’re one of the people who enjoy running and using Java and Linux-based microservice applications, then you’ll be pleased to know that a new Microsoft service is available for you to check out. The Azure Service Fabric has been designed to help simplify the process of managing applications that are solely based on a microservice architecture. The main aim of these microservice applications is to eventually be able to combine them into larger applications. Early user reports of the Fabric service have been positive, with many users highlighting the sheer speed of the service being one of the key factors behind its early success. While Microsoft has been using microservice architecture for a few years now, it’s one of the few dedicated services of its kind that have been…

“Could you tell us what Mycroft is and what its key aims are? Mycroft is the open source answer to voice-activated personal assistants like the Amazon Echo, Siri, Cortana, and Google Assistant. We felt this type of technology was too important to be strictly owned by these big players and therefore the idea of Mycroft was thought about and built upon. We hope that by developing an open source alternative we can empower developers and users around the world to voice-enable anything and to use this technology Does it work with most household IoT devices? Is it easy to link Mycroft to other devices? Currently we are working with the community to develop the skills promised in our Kickstarter: Nest, Philips Hue lights, etc. Of course, there’s a lot of…

If you currently run or you’re looking to run a Linux-based server for your home or small-to-medium size enterprise (SME), we’re here to help you choose the right hardware and the right software for your needs. Of course, exactly what your server build will look like will depend largely on which functions you want it to perform, but there are lots of considerations aside from raw performance, such as cost, future scalability, security and support. There are other aspects to consider, too. Is your use case best suited to a single server, or would multiple boxes be better? If, for example, you plan to have a machine doing a particularly CPU-intensive task (such as video transcoding), then you might want to move other functions such as web or file serving…

While there is plenty of guidance to help you choose the best hardware for an office or gaming PC, there isn’t as much available for server configurations – understandable perhaps, as it is a little bit more niche. The priorities when building a server, though, are very different – aside from having the appropriate performance to carry out the tasks for which it will be needed, there are additional considerations such as power usage, heat, noise, resilience and longevity. It doesn’t make sense to be upgrading a server frequently if you can choose the right components up front. Chassis The chassis (or case) might seem unimportant for a server compared to a desktop machine you’re going to use at home, but that’s not so – you’re just looking for different…

“Bash is not an island. Developers can create programs using a variety of other languages” Resources Bash gnu.org/software/ bash Qt Creator www.qt.io The scripting language of the Bash shell is Turing-complete. This means that it can be used to solve computing problems of arbitrary complexity. In practice, other languages are better suited to many computational tasks. For example, Bash is not object-oriented and does not support advanced mathematical operations. Being an interpreted language limits achievable performance due to the transpilation overhead. Finally, the relatively lenient runtime checks make finding syntax errors difficult. Fortunately, Bash is not an island. Developers can create programs using a variety of other languages – one interesting example would be Qt – which can then be invoked from shell scripts. This way, an object-oriented and natively…

Resources A text editor such as Emacs or vi The Go compiler This tutorial will continue the discussion of concurrent programming in Go. First, you will learn about the Go scheduler and shared memory. Then, as promised in the previous tutorial (last issue), a concurrent version of the wc utility will be developed. Then it will talk about buffered channels, the importance of the GOMAXPROCS environment variable and the select keyword. Last, it will show how to develop Go programs that use shared variables, which is the traditional way of exchanging data in concurrent programs, as well as the use of mutexes. The next and final tutorial in the Go series will talk about testing in Go, among other interesting things, so keep reading! What you should already know As…

With a name initially created for its developer's own website, where Lefebvre would regularly review distros and write about making tweaks to an OS, Linux Mint was soon an actual development project. Speaking to NetworkWorld.com, Lefebvre recalled, "It was something I experimented with. It's only after Linux Mint 2.2 'Bianca' that things got serious." Getting serious meant bringing people in to work alongside Lefebvre on the Linux distribution. Along with the ever-growing Linux Mint community, Jamie Birse and Kendall Weaver have both been credited with playing major parts in the Linux Mint story (although Weaver has since moved on to Peppermint OS). More recently, Frederic Gaudet has played a part, maintaining the KDE edition. But few took notice of Mint in its formative years, avoiding the distro until 2010, when…

In this age of ubiquitous surveillance it’s harder than ever to stop hackers, advertisers and shadowy government organisations from snooping on your browsing habits. However if you choose to connect through Tor, your connection is encrypted and passed through a number of proxies through a process known as ‘onion routing’. While this does slow down your connection, it also increases your privacy, making it extremely difficult to trace your actual current location. Follow the steps in this tutorial to turn your Pi into a wireless AP (Access Point) named Onion_Pi. Any devices connecting to Onion_Pi will do so over the Tor network. When you’re done, use a service like www.whatismyip.com to see that your location has changed. For more information about Tor visit https://www.torproject.org/about/overview.html.en. 01 Connect to Pi and check…

“It’s remarkably hard to compare it to other graphical boot managers and it’s near faultless when in use” RAM 1GB RAM Storage 1.4GB Versions 32-bit 64-bit When it comes to choosing your next distribution, anything based on Slackware tends to fall out of favour. That’s not saying that Slackware is bad by any means, but it’s instead statement to the level of improvements made throughout some of its competition. One of the main Slackware-based distributions that has generally held up well over the years is Salix, generally considered the premium choice for all of those who are seeking a CPU friendly slice of Slackware on their machine. Its latest edition (14.2) is actually based around the highly customisable and extremely lightweight Xfce 4.12 desktop environment. One of the first…

Whether through classic 8-bit micros, or Microsoft’s (in)famous Visual Basic, BASIC was the first programming language for many computer users. Non-believers may be aware of “GOTO considered harmful”, and may not have considered BASIC as a serious introductory language for modern needs. Both sides will need to revise their assumptions as Gambas (a recursive acronym unlocked as ‘Gambas Almost Means BASIC!’) is an object-oriented BASIC dialect with its own IDE, and an ease with GUI programming missing from some beginner languages. Packages may be available in your repository by the time this review is published. We compiled from source; the Gambas website gives a fairly comprehensive listing of dependencies needed but, at least in the case of Debian Jessie, left out libpoppler-private-dev, which didn’t upset the config script, but did…