Linux Blimp

Rygel is an open source project that provides users with both a command-line and graphical application that implements a lightweight UPnP media server. It has been tailored for users of the GNOME desktop environment.

Features at a glance

It allows Linux users to easily share video, picture and music files to any UPnP compatible device, locally or remote. For example, you can access the files from your PC or laptop with another computer, smart TV, gaming console, tablet, smartphone or media center devices.

In other words, with Rygel you will be able to browse and play media stored on a computer through a PlayStation or Xbox console, easily search and play media using a laptop, phone or smart TV, as well as to redirect sound output to DLNA speakers.

Command-line options

On the other hand, the command-line, which is the most important part of the program, empowers users to disable media transcoding, disallow upload and deletion of files, set a specific network interface and port, and set the path of a certain engine or plugin.

Additionally, it can be used to disable a certain plugin, set plugin titles and options, disable UPnP for a streaming-only operation, force the program to use a specific configuration file instead of the default user configuration, shutdown remote Rygel reference, and use comma-separated list of domain:level pairs for logging.

Under the hood

Being written in the Vala programming language, the application provides users with a GTK+ graphical user interface, accessible with the rygel-preferences command, that allows them to share media through the DLNA (Digital Living Network Alliance) protocol, add or remove dedicated media folders, and add or remove network interfaces.

The application is based on the GUPnP framework and supports pluggable media providers. It is the most lightweight and easy to use UPnP media server for Linux-based operating systems. But if you want more, you should try XBMC or Plex Media Server.

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Nagios is one of the most popular open source monitoring system. Nagios keeps an inventory of your entire IT infrastructure and ensures your networks, servers, applications, services, and processes are up and running.

In case of failure or suboptimal performance Nagios will send notification alerts via various methods.

This tutorial will guide you through the steps required to install and configure the latest version of Nagios Core on Ubuntu 18.04.

An older version of Nagios (version 3) is available in the Ubuntu software repository and can be easily installed with apt install nagios3.

Prerequisites

Before continuing with this tutorial, make sure you are logged in as a user with sudo privileges.

Update your Ubuntu system and install the following packages which are necessary to download and compile the Nagios main application and Nagios plugins:

sudo apt update && sudo apt upgrade
sudo apt install autoconf gcc libc6 make wget unzip apache2 php libapache2-mod-php7.2 libgd-dev
sudo apt install libmcrypt-dev libssl-dev bc gawk dc build-essential libnet-snmp-perl gettext

Installing Nagios on Ubuntu

The following steps describes how to install the latest version of Nagios Core from source.

1. Downloading Nagios

We are going to download Nagios source in the /usr/src directory which is the common location to place source files, change to the directory with:

Download the latest version of Nagios from the project Github repository using the following wget command:

sudo wget https://github.com/NagiosEnterprises/nagioscore/archive/nagios-4.4.2.tar.gz

When the download is complete extract the tar file with:

sudo tar zxf nagios-*.tar.gz

Before continuing with the next steps, make sure you change to the Nagios source directory by typing:

2. Compiling Nagios

To start the build process run the configure script which will perform a number of checks to make sure all of the dependencies on your system are present:

sudo ./configure –with-httpd-conf=/etc/apache2/sites-enabled

Upon successful completion, the following message will be printed on your screen:

*** Configuration summary for nagios 4.4.2 2018-08-16 ***:

General Options:
————————-
Nagios executable: nagios
Nagios user/group: nagios,nagios
Command user/group: nagios,nagios
Event Broker: yes
Install $: /usr/local/nagios
Install $: /usr/local/nagios/include/nagios
Lock file: /run/nagios.lock
Check result directory: /usr/local/nagios/var/spool/checkresults
Init directory: /lib/systemd/system
Apache conf.d directory: /etc/apache2/sites-enabled
Mail program: /bin/mail
Host OS: linux-gnu
IOBroker Method: epoll

Web Interface Options:
————————
HTML URL: http://localhost/nagios/
CGI URL: http://localhost/nagios/cgi-bin/
Traceroute (used by WAP):

Review the options above for accuracy. If they look okay,
type ‘make all’ to compile the main program and CGIs.

You can now start the compilation process using the make command:

The compilation may take some time, depending on your system. Once the build process is completed, you will be presented with the following message:

3. Creating Nagios User And Group

The following command will create a new system nagios user and group:

sudo make install-groups-users

Add the Apache www-data user to the nagios group:

sudo usermod -a -G nagios www-data

4. Install Nagios Binaries

Perform the following command to install Nagios binary files, CGIs, and HTML files:

You should see the following output:

*** Main program, CGIs and HTML files installed ***

5. Creating External Command Directory

Nagios can process commands from external applications. Create the external command directory and set the proper permissions by typing:

sudo make install-commandmode*** External command directory configured ***

6. Install Nagios Configuration Files

Install the sample Nagios configuration files with:

*** Config files installed ***

Remember, these are *SAMPLE* config files. You’ll need to read
the documentation for more information on how to actually define
services, hosts, etc. to fit your particular needs.

7. Install Apache Configuration Files

The command below will install the Apache web server configuration files:

sudo make install-webconf*** Nagios/Apache conf file installed ***

Make sure Apache rewrite and cgi modules are enabled:

sudo a2enmod rewrite
sudo a2enmod cgi

8. Creating User Account

To be able to access the Nagios web interface you’ll need to create an admin user called nagiosadmin

Using the following htpasswd command to create a user called nagiosadmin

sudo htpasswd -c /usr/local/nagios/etc/htpasswd.users nagiosadmin

You will be prompted to enter and confirm the user’s password.

New password:
Re-type new password:
Adding password for user nagiosadmin

Restart the Apache service for changes to take effect:

sudo systemctl restart apache2

9. Configuring Firewall

The firewall will secure your server against unwanted traffic.

If you don’t have a firewall configured on your server, you can check our guide about how to setup a firewall with ufw on ubuntu

Open the Apache ports by typing run:

Installing Nagios Plugins

Switch back to the /usr/src directory and ownload the latest version of the Nagios Plugins from the project Github repository:

cd /usr/src/
sudo wget -O nagios-plugins.tar.gz https://github.com/nagios-plugins/nagios-plugins/archive/release-2.2.1.tar.gz

Once the download is complete extract the tar file by typing:

sudo tar zxf nagios-plugins.tar.gz

Change to the plugins source directory and compile by typing:

cd nagios-plugins-release-2.2.1

Run the following commands one by one to compile and install the Nagions plugins:

sudo ./tools/setup
sudo ./configure
sudo make
sudo make install

Starting Nagios

Now that both Nagios and its plugins are installed, start the Nagios service with the following command:

sudo systemctl start nagios

To verify that Nagios is running, check the service status with the following command:

sudo systemctl status nagios

The output should look something like bellow indicating that Nagios service is active and running.

* nagios.service – Nagios Core 4.4.2
Loaded: loaded (/lib/systemd/system/nagios.service; enabled; vendor preset: enabled)
Active: active (running) since Fri 2018-11-16 14:54:21 PST; 1s ago
Docs: https://www.nagios.org/documentation
Process: 18294 ExecStopPost=/bin/rm -f /usr/local/nagios/var/rw/nagios.cmd (code=exited, status=0/SUCCESS)
Process: 18293 ExecStop=/bin/kill -s TERM $ (code=exited, status=0/SUCCESS)
Process: 18315 ExecStart=/usr/local/nagios/bin/nagios -d /usr/local/nagios/etc/nagios.cfg (code=exited, status=0/SUCCESS)
Process: 18313 ExecStartPre=/usr/local/nagios/bin/nagios -v /usr/local/nagios/etc/nagios.cfg (code=exited, status=0/SUCCESS)
Main PID: 18325 (nagios)
Tasks: 6 (limit: 2319)
CGroup: /system.slice/nagios.service

Accessing the Nagios Web Interface

To access the Nagios web interface open your favorite browser and type your server’s domain name or public IP address followed by /nagios:

http(s)://your_domain_or_ip_address/nagios

Enter the nagiosadmin user login credentials and you will be redirected to the default Nagios home page as shown on the image below:

Conclusion

You have successfully installed the latest Nagios version from source on your Ubuntu system.

You should now check the Nagios Documentation and learn more about how to configure and use Nagios.

If you hit a problem or have a feedback, leave a comment below.

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Whenever you login into your computer, you’re presented with a screen asking your credential to verify that it’s you. After you enter the password, you’re in your world. Each time you log in, you have to go through this process again and again. Doesn’t it feel boring to look at the face of that same, plain screen? I bet you’re pretty tired of the system’s default login screen. Well, let’s add a splash of color! Having an awesome background would really rejuvenate your desktop experience, don’t you agree? Ubuntu is the most popular Linux distro for general users, no doubt. However, over the course of its lifetime, there’s that same, BORING login screen appearing. It’s time to change that.

Ubuntu shifted from Unity to GNOME desktop environment and GDM as login agent. By default, Ubuntu allows you to modify your desktop wallpaper and lock screen background. However, there’s no direct option available for changing the login screen background. We’ll have to dig our way through various system tweaks.

At first, make sure that you have your background image ready.

Now, fire up a terminal and run the following commands –

sudo cp ~/Desktop/mybackground.png /usr/share/backgrounds

Or, you can also use the file manager to do the task.

xhost +local: && sudo nautilus /usr/share/backgrounds/

Now, you have to edit the CSS file that defines the login background.

Xhost +local: && sudo gedit /etc/alternatives/gdm3.css

Now, find out the following section –

Change the “background” entry –

#lockDialogGroup {
background: url(file:///usr/share/backgrounds/mybackground.png);
background-repeat: no-repeat;
background-size: cover;
background-position: center; }

Save the file.

Enjoying the effect

After everything is complete, restart your system.

Voila! Enjoy the most amazing login screen backgrounds of your entire life!

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Gedit is an open source text editor application for Linux-based operating systems. It is mostly used under the GNOME desktop environment, but you can also install it on other open source window managers.

It is more than a simple text editor, as it can be used by developers as a programmers’ editor. The software provides users with an uncluttered user interface that can be used by novices and expert users alike.

Recognizes numerous programming languages

Gedit features full support for internationalized text (UTF-8), configurable syntax highlighting for various languages, such as C, C++, Java, XML, HTML, Python, Perl, undo and redo functions, as well as the ability to load files from remote locations.

Talking about supported programming languages, the application automatically detects the syntax of a certain file, but it also allows users to choose one from the statusbar or the Highlights Mode entry of the View menu.

Features at a glance

Its main features include spell checking support with automatic highlighting of misspelled words, advanced document statistic functionality that displays the total number of lines, words, bytes, as well as characters, with or without spaces, in the entire document or the current selection.

Among other features we can mention file reverting, print and print preview support, clipboard support (cut, copy, paste), search and replace, go to specific line, auto indentation, text wrapping, line numbers, right margin, current line highlighting, bracket matching, file backup, and configurable colors and fonts.

Supported OSes and availability

While the application is distributed only as a source archive that can be configured, compiled and installed on any Linux flavor, users can find and install Gedit straight from the default software repositories of their distribution.

With a complete online user manual, Gedit can be easily used by programmers to successfully write and edit code. Besides Linux, the application also supports the Mac OS X and Microsoft Windows operating systems.

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Nowadays, you don’t have to put much effort into accessing your data. Whenever you create a file on your phone, laptop, or any other device, you can easily save it somewhere which all of your devices have access to. This makes it possible to access your important documents wherever you are, and this is something which people are getting far too used to. In fact, for some, moving data without the help of the internet sounds like witchcraft, especially when there isn’t a memory stick involved. To show you just how easy this is, this post will be exploring the three main operating systems, Linux, Mac OS, and Windows, giving you an idea of what to expect from their peer-to-peer data transfer systems.

Linux

Starting with the easiest option, Linux makes it very simple to move data between machines, as long as you’re used to using the OS in the first place. You’ll need to use

an SSH server

for this, enabling you to send and receive files using the command prompt. When this is setup properly, you will have access to all of the unrestricted files on the machine which you’re connected to. Unfortunately, thanks to this method requiring a server, the files will only be able to move one way without a switch each time you want to swap them around. This can be achieved without a single cable, as long as your machines are connected in some way.

Mac OS

True to their usual form, Apple make this process easier than anyone else. Using the normal iCloud app which is already installed on your machine, you can start transferring files to any other Mac which is logged into the same account. If you’d prefer to remain on seperate accounts, though, a tool called Forklift can be downloaded for free. You have been able to sync files between Macs without cloud for a long time. Only recently, though, have people been using systems like this as a replacement for sharing online.

Windows

Surprisingly, Windows makes this process a little harder than its alternatives. Instead of giving you a fancy tool to use out of the box, you have to configure your machines to use the same subnet and IP address range if you

want them to connect

. Along with this, they will also need to be on the same network, and the best results will be found if you use wired connections. There is a UI to help you with this, and it can be found in the Homegroup settings within Control Panel. Of course, though, even with a little bit of help, most inexperienced users will find this route impossible to follow without the right help.

Hopefully, this post will inspire you to start looking at new ways to share data between the machines you use. Even if you don’t have any issues with the Internet, this sort of system can be far more secure than relying on the cloud, making it perfect for those who need to share sensitive information around.

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In terms of security, Linux is definitely one of the tightest. The password system is one of the most important parts. Without the password, you’re not able to access a secure system and do anything. If you allow system access without a password, it is not secure. No password, no nothing, in terms of security. However, you may also need to change your password at any point. Let’s have a look at changing the password of your system.

Changing the password

This is the password that you have to enter when you’re logging into your account. This password isn’t the “root” password. Let’s fire up a terminal and run the following command –

This will prompt you to enter your current password. Then, you have to type your new password 2 times.

Changing the “root” password

The “root” is the ultimate user account for any Linux system that offers the most control over the system, even allowing access to sensitive system files and other files. For changing the “root” password, run the following command –

# OR

Then, restart your system.

Changing password without the current “root” access

In cases, you may not be able to access to your system because you forgot the “root” password. It’s also possible to change the password without having access to the system. Restart your system.

Keep holding “Shift” to access the GRUB menu.

Press “E” for editing the startup command.

Get to the line “linux /boot”.

At the end of “ro”, type the following text –

Press “Ctrl + X” to boot with the modified startup command. Run the following commands –

mount -o remount,rw /
passwd

Enter your new password. After password changing is successful, run the following command for restarting your system –

Voila! Your password is changed successfully!

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VTE (Virtual Terminal Emulator) is an open source and totally free library software that has been designed from the ground up to act as a terminal emulator widget for the GTK+ 2.0 (or higher) toolkit. It can be used by GNOME developers to inject terminal capability strings inside a tree of tables.

It is used by GNOME Terminal

VTE is a terminal widget used by the GNOME Terminal application, but it can also be used to embed a console/terminal in editors, IDEs, games, etc. VTE includes libvte, a library that implements a terminal emulator widget for GTK+, and the vte program, a sample application that wraps that widget in a GTK window.

Application options

The application features several options, such as the ability to disable the use of anti-aliasing, specify a background image, monitor /dev/console, highlight URLs inside a terminal emulator, disable rewrapping on resize, execute commands in the terminal, as well as to disable double-buffering.

Additionally, users will be able to disable spawning of a shell inside the terminal emulator, enable the use of a transparent background, use visible and audible alerts, enable the use of various debugging checks, set the position and size of the terminal and enable a distinct highlight color for selections.

The GNOME virtual terminal editor

Being associated with the GNOME project, VTE is also known as a virtual terminal editor program for the controversial GNOME graphical desktop environment, as well as for the powerful GTK+ toolkit.

Under the hood and availability

The software is written entirely in the C programming language and it’s distributed along with the GNOME project. It can be downloaded from its official website or via Softpedia as a universal tarball, which can be installed in any GNU/Linux distribution. VTE is also available on the default software repositories of many Linux distributions.

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Imagine what the world would look like if growth, innovation, and development were free from fear. Innovation without fear is fostered by consistent, predictable, and fair license enforcement. That is what the GPL Cooperation Commitment aims to accomplish.

Last year, I wrote an article about licensing effects on downstream users of open source software. As I was conducting research for that article, it became apparent that license enforcement is infrequent and often unpredictable. In that article, I offered potential solutions to the need to make open source license enforcement consistent and predictable. However, I only considered “traditional” methods (e.g., through the court system or some form of legislative action) that a law student might consider.

In November 2017, Red Hat, IBM, Google, and Facebook proposed the the “non-traditional” solution I had not considered: the GPL Cooperation Commitment, which provides for fair and consistent enforcement of the GPL. I believe the GPL Cooperation Commitment is critical for two reasons: First, consistent and fair license enforcement is crucial for growth in the open source community; second, unpredictability is undesirable in the legal community.

Understanding the GPL

To understand the GPL Cooperation Commitment, you must first understand the GPL’s history. GPL is short for GNU General Public License. The GPL is a “copyleft” open source license, meaning that a software’s distributor must make the source code available to downstream users. The GPL also prohibits placing restrictions on downstream use. These requirements keep individual users from denying freedoms (to use, study, share, and improve the software) to others. Under the GPL, a license to use the code is granted to all downstream users, provided they meet the requirements and conditions of the license. If a licensee does not meet the license’s requirements, they are non-compliant.

Under the second version of the GPL (GPLv2), a license automatically terminates upon any non-compliance, which causes some software developers to shy away from using the GPL. However, the third version of the GPL (GPLv3) added a “cure provision” that gives a 30-day period for a licensee to remediate any GPL violation. If the violation is cured within 30 days following notification of non-compliance, the license is not terminated.

This provision eliminates the fear of termination due to an innocent mistake, thus fostering development and innovation by bringing peace of mind to users and distributors of the software.

What the GPL Cooperation Commitment does

The GPL Cooperation Commitment applies the GPLv3’s cure provisions to GPLv2-licensed software, thereby protecting licensees of GPLv2 code from the automatic termination of their license, consistent with the protections afforded by the GPLv3.

The GPL Cooperation Commitment is important because, while software engineers typically want to do the right thing and maintain compliance, they sometimes misunderstand how to do so. This agreement enables developers to avoid termination when they are non-compliant due to confusion or simple mistakes.

The GPL Cooperation Commitment spawned from an announcement in 2017 by the Linux Foundation Technical Advisory Board that the Linux kernel project would adopt the cure provision from GPLv3. With the GPL Cooperation Commitment, many major technology companies and individual developers made the same commitment and expanded it by applying the cure period to all of their software licensed under GPLv2 (and LGPLv2.1), not only to contributions to the Linux kernel.

Broad adoption of the GPL Cooperation Commitment will have a positive impact on the open source community because a significant amount of software is licensed under GPLv2. An increasing number of companies and individuals are expected to adopt the GPL Cooperation Commitment, which will lead to a significant amount of GPLv2 (and LGPLv2.1) code under license terms that promote fair and predictable approaches to license enforcement.

In fact, as of November 2018, more than 40 companies, including industry leaders IBM, Google, Amazon, Microsoft, Tencent, Intel, and Red Hat, have signed onto the GPL Cooperation Commitment and are working collaboratively to create a standard of fair and predictable enforcement within the open source community. The GPL Cooperation Commitment is just one example of how the community comes together to ensure the future of open source.

The GPL Cooperation Commitment tells downstream licensees that you respect their good intentions and that your GPLv2 code is safe for them to use. More information, including about how you can add your name to the commitment, is available on the GPL Cooperation Commitment website.

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There was a time when deploying software was an event, a ceremony because of the difficulty that was required to keep this consistency. Teams spent a lot of time making the destination environments run the software as the source environment. They thereafter prayed that the gods kept the software running perfectly in production as in development.

With containers, deployments are more frequent because we package our applications with their libraries as a unit making them portable thereby helping us maintain consistency and reliability when moving software between environments. For developers, this is improved productivity, portability and ease of scaling.

Because of this portability, containers have become the universal language of the cloud allowing us to move software from one cloud to another without much trouble.

In this article, I will discuss two major concepts to note while working with containers in Ruby. I will discuss how to create small container images and how to test them.

Read more at The New Stack

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Four years on from the release of Red Hat Enterprise Linux 7, open source software company Red Hat Inc. finally announced today that version 8 of its computer server operating system is now in beta.

A lot has changed in the world of Linux during that time, with vastly more workloads running in public clouds and more agile software development practices increasingly becoming the norm. The new RHEL reflects those differences.

Whereas the RHEL 7 release was all about better support for virtual machines and improved Windows interoperability, today’s version gives a nod to the fact that most information technology operations are increasingly all about the cloud and software containers.

The public beta release of RHEL 8 is important because Linux is the most dominant server operating system for both on-premises and cloud infrastructure, Constellation Research Inc. analyst Holger Mueller told SiliconANGLE. And of the companies that sell Linux OS platforms, Red Hat is one of the biggest. Late last month, IBM Corp. said it signed a deal to acquire the company for $34 billion, though the acquisition won’t close until well into next year.

“When a key vendor like RedHat updates its Linux OS, executives pay close attention to the rate of innovation and how much it has future-proofed the platform,” Mueller said. “We expect RedHat to get good grades in both regards, thanks to its focus on changing the underlying platform to receive more granular updates and [the improved] container capabilities.”

As always, Red Hat has made literally hundreds of improvements to its flagship software platform. Still, one stands out from the pack.

RHEL 8 introduces a new concept called Application Streams, which are designed to deliver “userspace packages.” That refers to independent software code that runs outside of the OS’s kernel, more easily and with greater flexibility.

So userspace packages, which could be the latest version of a programming language, for example, can now be updated without needing to wait for a new version of Red Hat’s operating system to come out. The idea is that this will help enterprises become more agile and customize their IT infrastructure better, without breaking anything along the way.

Application Streams also allow companies to use more than one version of the same userspace package simultaneously. This allows for much greater freedom, as it means developers can work with the latest release of a new database for example, while production apps keep running the stable release developers are sure the new one works smoothly.

Red Hat has also improved networking for containers, which are isolated development environments used to build applications that can run on any platform. The release introduces a new Transmission Control Protocol and Internet Protocol or TCP/IP stack that increases bandwidth and boosts other networking functions, with the aim of providing superior performance for video streaming and other services.

There’s also a new container toolkit for developers to play with. It includes the latest version of Buildah, which is used to create containers; Podman, which is used to get them up and running; and Skopeo, which is a tool for sharing containerized apps. The idea is to help developers build, run and share their container-based apps more easily.

On the security side, RHEL 8 brings the latest OpenSSL 1.1.1 and Transport Layer Security 1.3 releases to the table. OpenSSL is a software library for applications that secure communications over computer networks against eavesdropping or need to identify the party at the other end. Meanwhile, TLS is a cryptographic protocol that provides end-to-end communications security over networks and is widely used for internet communications and online transactions. Red Hat said it hopes the updates here can ease headaches around regulatory compliance issues.

RHEL 8 should also be simpler to manage due to the addition of single user control via the Web Console, while the new RHEL Composer provides a way for users to create and deploy container images across multiple cloud platforms, including private, public and virtual ones.

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