AMD’s RX 480 has been out for a little over a week now, and in that week Linux gamers have been clamoring or information on whether and how the card works on their favorite distribution. Sure, Ubuntu 16.04 is officially supported by AMD’s proprietary Pro drivers, but what about everyone else, and what if you want to use those AMDGPU open source drivers that have been in the works for so long? Well, it’s definitely possible, but it’s not all that easy.

WARNING: Here be dragons, big ones. They’re pretty much the kind you’d expect to see flying around Mereen, so if you don’t want to take the chance of breaking your install and some singed eyebrows, turn back now.

July 08, 2016
by Rares Aioanei

Introduction

As the title might suggest, this article will show you how to run X applications without using a window manager or desktop environment. You might ask yourself : why would I want to do that? Well, you might want to run a kiosk system where you only need to run the browser and/or the hardware resources are limited. Or you simply use only one/a few X applications and spend the rest of the time in a terminal so you don't need the overhead of a window manager. Or, last but not least, because it's an interesting experiment, akin to the one where you have to spend X days exclusively in a terminal. Also, it's fun! So let's get started.

Making sure we have all we need

What you need is pretty simple : a minimal Linux distribution or a similar Unix-like OS with the desired X applications installed and Xorg. In RHEL-based distributions installing Xorg is accomplished by doing
 $ sudo yum install xorg-x11*
while in Debian-based operating systems this is done with
 $ sudo apt-get install xorg

Sharing files between computers and servers is an essential networking task. Thankfully, Linux’s NFS(Networked File System) makes it extremely easy. With NFS properly configured, moving files between machines is as easy as moving files around on the same machine. Since NFS functionality is built directly into the Linux kernel, it is both powerful and available on every distro, though the configuration differs slightly between them.

Setting Up The Server

Installing The Packages

Linux NFS uses the Client-Server model, so the first step in getting NFS set up is setting up the server. Because the core NFS capabilities are rooted in the kernel, there isn’t much required in the way of packages, but there are still a few regardless of the distribution as well as some configuration. Almost all major distributions have NFS enabled, so unless you’re running a custom one, it should already be set up. The next step in getting the server set up is to install the packages.
On Ubuntu/Debian:
$ sudo apt-get install nfs-kernel-headers
On Fedora
$ sudo yum install nfs-utils system-config-nfs

Introduction

By creating a Logical Volume snapshots you are able to freeze a current state of any of your logical volumes. This means that you can very easily create a backup and once needed rollback to a original logical volume state. This method is very similar to what you already know from using Virtualization software such as Virtualbox or VMware where you can simply take a snapshot of entire virtual machine and revert back in case something went wrong etc. Therefore, using LVM snapshots allows you to take a control of your system's logical volumes whether it is your personal laptop or server. This tutorial is self-contained as no previous experience with Logical Volume Manager is required.

Scenario

In this article we will explain how to manually create and restore logical volume snapshots. Since we do not assume any previous experience with Logical Volume Manager we will start from a scratch using a dummy physical hard drive /dev/sdb with size of 1073 MB. Here are all steps in nutshell:

  • First we will create two partitions on our /dev/sdb drive. These partitions will be of "8e Linux LVM" type and will be used to create a physical volumes
  • Once both partitions are created we use pvcreate command to create physical volumes
  • In this step we create a new Logical Volume Group and a single 300MB in size logical volume using ext4 filesystem
  • Mount our new logical volume and create some sample data
  • Take a snapshot and remove sample data
  • Rollback logical volume snapshot

Introduction

For many years people have wanted to protect their right to privacy. As technology changes, it seems that privacy evolves away more and more. I2P is a protocol used for an encrypted multi-proxy on the Internet. While, this sounds simple, there is actually a lot of work going on with I2P to achieve this. Unlike some multi-proxies, I2P will allow you to tunnel many more applications through it than just web browsing, making it a very robust protocol.

I2P is available for all platforms, not just Linux. For this example I have used Debian Sid to perform the installation. With the exception of 'apt-get', these instructions should work fine with any Linux distribution. But if you experience problems, please seek documentation for your distro.

Legal Disclaimer

As I explain this to help you maintain priviacy, there will always be a few bad apples in the crowd. I do not condone this use of this article for anything illegal. Even if you are not passing illegal information on I2P, please check your country's laws on encryption and it's exportation before you begin.

The Problem with Tor

One would probably see I2P as an overkill without knowing the downfalls of its predecessor. Tor was once a wonderful multi-proxy used for hiding ip addresses and bouncing off servers all over the world. At one time, it was even trusted by most governments for strong anonymity. All of that seemed to change after an article was posted in 2600 Hacker Quartley. One author exposed how becoming an exit node for Tor allowed all the traffic on the Tor network to pass right through your machine. Becoming an exit node was the same as performing a Man-In-The-Middle attack. All one had to do was open up a packet sniffer and see all the traffic going through encrypted. Tor is still used by people trying to protect their privacy. But at the same time it has become a playground for hackers and governments monitoring what they consider suspicious. I2P has secured this problem while adding more functionality.

WARNING: This process will erase all information from the Chromebook hard drive. As with all firmware flashes, there is a chance of something going wrong, rendering the device useless. Proceed at your own risk.

Chromebooks are everywhere. Google’s little Linux based PCs have been booming since their introduction several years ago in everything from homes to businesses, and even educational settings. Many users, especially Linux users, can’t get past the fact that the devices are hopelessly hamstrung by their ChromeOS operating system which both cuts down on the number of apps the device can run and makes it dependent on an Internet connection to get anything done.
Acer C7 running Gentoo

So, what does a Linux user believing in the potential of their little (sort of)Linux laptop do? Break everything Google did. In many cases, Chromebooks are supported by the FOSS Coreboot project, meaning that there is a completely unlocked, free and open source version of the Chromebook BIOS just waiting to be installed. With a few relatively simple steps, that \$300 Chromebook can become a full fledged Linux laptop running just about any distribution. It should be noted that you should check which type of processor your Chromebook is running first, this method only supports Intel based Chromebooks. Another thing to keep in mind before getting started is that there are a ton of different Chromebooks. This method was tested with the extremely common Acer 7XX series, but it should work(maybe with subtle differences) on other Chromebooks as well.

March 12, 2013
by Lubos Rendek

Introduction

Whether you are administrating a small home network or an enterprise network for a large company the data storage is always a concern. It can be in terms of lack of disk space or inefficient backup solution. In both cases GlusterFS can be the right tool to fix your problem as it allows you to scale your resources horizontally as well as vertically. In this guide we will configure the distributed and replicated/mirror data storage. As the name suggests a GlusterFS's distributed storage mode will allow you to evenly redistribute your data across multiple network nodes, while a replicated mode will make sure that all your data are mirrored across all network nodes.

What is GlusterFS

After reading the introduction you should have already a fair idea what GlusterFS is. You can think of it as an aggregation service for all your empty disk space across your whole network. It connects all nodes with GlusterFS installation over TCP or RDMA creating a single storage resource combining all available disk space into a single storage volume ( distributed mode ) or uses the maximum of available disk space on all notes to mirror your data ( replicated mode ). Therefore, each volume consist of multiple nodes, which in GlusterFS terminology are called bricks.

Preliminary Assumptions

Although GlusterFS can by installed and used on any Linux distribution, this article will primarily use Ubuntu Linux. However, you should be able to use this guide on any Linux Distribution like RedHat, Fedora, SuSe, etc. The only part which will be different will be the GlusterFS installation process.

Furthermore, this guide will use 3 example hostnames:

  • storage.server1 - GlusterFS storage server
  • storage.server2 - GlusterFS storage server
  • storage.client - GlusterFS storage client

Use DNS server or /etc/hosts file to define your hostnames and adjust your scenario to this guide.

Introduction

Steganography is the art of hiding messages within other messages or data. Most commonly we see this utilized with pictures. This is probably encryption at its finest.
Mostly because it doesn't look like usual garbled text that we are used to seeing with encryption. The changes made by Steganography are so slight the human eye cannot perceive them. Even trained cryptographers may have an encoded message inside a picture and be unaware of it. There is a very deep science to this. Usually this is done by flipping parity bits at the binary level. While it is great to learn how this works, sometimes it can be a very tedious job. Fortunately for us there is a tool that will take away most of the grunt work.

Introduction

This article describes an installation of SysAid software on a Linux system using tomcat and Apache. SysAid is a commercial web-based help desk software and if you were thinking to install either its free or paid version in your organization this guide should help you to achieve it. The default installation of SysAid IT help desk is quite very straight forward. On top of this basic installation this guide will provide you with some extra settings on how to configure SysAid with apache's https service using AJP proxy.

Introduction and concepts

Every system administrator I know develops in time the habit of putting together a toolbox where, as time passes, many useful pieces of software get added up, as the recurrent need arises. Please do not imagine this in the most classical of the sense, as this is not about a carpenter's toolkit, nor a mechanic's toolbox. It usually is a CD portfolio with live CDs, installable most-used distributions, vendor-specific tools and whatever not. Of the (indispensable) live CDs, one usually sees in the aforementioned toolbox a disk cloning item. What does it do? It helps a tremendous amount when you need to save and restore a hard disk, operating system included, and by save I mean 1/1 copy with the possibility of restoring in a few minutes, despite the ever-increasing size of the hard drives offered by the market today, where the terabyte becomes more and more common.

Such software exists, and indeed it makes the lives of admins and users alike much easier and efficient. Unfortunately, companies tried to impose their own proprietary disk image formats, so that restoring could be possible only by using their tools. Fortunately, there is a FOSS solution that deals with this, offering a very efficient live CD and server for download, and that is Clonezilla, which we'll talk about today. You are expected to have some knowledge on how disks work, networking and system administration. We will treat more advanced subjects a bit later on, but all you need to know if you are a beginner in those matters is right here.

Introduction

As a Linux system administrator you will be required to manage user accounts. This can be done by adding or removing user logins or simply by temporarily or permanently disabling an entire account while leaving the user's profile and files intact. This article describes a few ways on how to disable the user account in the Linux operating system.

Shadow file modification

The easiest way to disable the user account is to modify a /etc/shadow file, which is responsible for holding encrypted passwords for users listed /etc/passwd. Here is a typical user entry found in the /etc/shadow file:

tester:$6dKR$Yku3LWgJmomsynpcle9BCA:15711:0:99999:7:::

Introduction

Any decent Linux distribution comes with an installation option to automatically encrypt user's home directory. In case you do not wish to encrypt the entire home directory or perhaps you wish to encrypt some random directories on your Linux system you can use EncFS the FUSE-based cryptographic filesystem. EncFS will allow you to encrypt and decrypt any directory in a matter of seconds. It will reside on top of your current filesytem and provide access to any EncFS encrypted directory only upon entering a correct predefined password. This short tutorial will show you how to encrypt and decrypt your directories with the EncFS cryptographic filesystem.

Scenario

Let's assume that you are a heavy Laptop user traveling from one place to another. You also use ssh quite often and so you have generated ssh keypair. For your convenience you even generated a private key without using a pass-phrase ( never good idea ). Furthermore, you have copied you public ssh key to multiple servers for an easy access. The problem with this scenario is that once someone gets hold of your Laptop s/he gets instantly access to all servers using you private ssh key. In this article we will show you how to encrypt your .ssh directory and avoid such problem.

Introduction

If you've ever been in charge of a network you've definitely had the need for a secure remote connection. Maybe you just need to keep an eye on employees or kids. Doing so can be a hassle to some while crossing networks and subnets. On top of that, many businesses may have Internet but no DHCP to more protected machines. Many do this to network machines while keeping employees from surfing the Web. Whatever the case, Linux has many great tools to enable remote encrypted GUI administration. Even better, we will get everything we need for free for accessing a Linux or Windows client.

Introduction

When navigating the Linux file system you are sure to encounter different file types. The most used and obvious file types are regular files and directories. However, the Linux operating system has more to offer in terms of file types as it also includes another 5 file types. This short article will help you to recognize all the 7 different file types within the Linux operating system.

Identifying Linux File types

There is only 1 command you need to know, which will help you to identify and categorize all the seven different file types found on the Linux system.

$ ls -ld <file name>

Here is an example output of the above command.

 $ ls -ld /etc/services 
-rw-r--r-- 1 root root 19281 Feb 14 2012 /etc/services

ls command will show the file type as an encoded symbol found as the first character of the file permission part. In this case it is "-", which means "regular file". It is important to point out that Linux file types are not to be mistaken with file extensions. Let us have a look at a short summary of all the seven different types of Linux file types and ls command identifiers:

  1. - : regular file
  2. d : directory
  3. c : character device file
  4. b : block device file
  5. s : local socket file
  6. p : named pipe
  7. l : symbolic link

Introduction

In this article we will look on how to automatically chroot jail selected user ssh login based on the user group. This technique can be quite useful if you what your user to be provided with a limited system environment and at the same time keep them separate from your main system. You can also use this technique to create a simple ssh honeypot. In this tutorial you will learn how to create a basic chroot environment and how to configure your main system's sshd to automatically chroot jail selected users upon the ssh login.

Creating basic chroot environment

First we need to create a simple chroot environment. Our chroot environment will consist of a bash shell. To do this, first, we need to create a chroot directory:

# mkdir /var/chroot

In the next step, we need to copy the bash binary and its all shared library dependencies.
You can see the bash's shared library dependencies by executing the ldd command:


# ldd /bin/bash
linux-vdso.so.1 => (0x00007fff9a373000)
libtinfo.so.5 => /lib/x86_64-linux-gnu/libtinfo.so.5 (0x00007f24d57af000)
libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007f24d55ab000)
libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f24d51eb000)
/lib64/ld-linux-x86-64.so.2 (0x00007f24d59f8000)

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