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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 revert back 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 laptop or server. This tutorial is self-contained as no previous experience with Logical Volume Manager is required.

Most of the time as a system administrator you are managing your servers over the network. It is very rare that you will need to have a physical access to any of your managed servers. In most cases all you need is to SSH remotely to do your administration tasks. In this article we will configure a GUI alternative to a remote access to your RHEL server, which is VNC. VNC allows you to open a remote GUI session to your server and thus providing you with a full graphical interface accessible from any remote location.

If your Redhat server is not connected to the official RHN repositories, you will need to configure your own private repository which you can later use to install packages. The procedure of creating a Redhat repository is quite simple task. In this article we will show you how to create a local file Redhat repository as well as remote HTTP repository.

Logrotate is a utility designed for administrators who manage servers producing a high volume of log files to help them save some disk space as well as to avoid a potential risk making a system unresponsive due to the lack of disk space. Normally, a solution to avoid this kind of problem is to setup a separate partition or logical volume for a /var mount point. However, logrotate may also be a viable solution to this problem especially if it is too late to move all logs under different partition. In this article we will talk about usage and configuration of logrotate on RedHat / CentOS Linux server.

If you ever wondered whether you have the right skills set or what Linux/Unix related skills are currently highly on demand, now you have a chance to confirm if your current understating of IT skills market is correct. Apart of a fresh new look of our website we have introduced some new features such as "IT Skills Watch", which will keep you updated if the skills you posses still spark an interest of recruiters and employers. Such statistics will be regularly revised. We have considered approximately 150 IT skills, dozen operating systems and hundreds network protocols. The higher the score the more likely you are to find that particular skill, operating system or certification requirement on the job description you wish to apply for. It is important to point out that aiming for the top rank skills may increase your chances but does not ensure a successful interview. The right combination of various skills is more vital to your success.

The aim of this article is to provide an overview of the GNU R programming language. It starts a series of articles devoted to programming with R. Its objective is to present, in an organized and concise manner, the elementary components of the R programming language. It is designed to help you understand R code and write your own. It is assumed that the reader has already some basic programming knowledge of R. If you are not familiar with any of R features it is recommended that you first read A quick GNU R tutorial to basic operations, functions and data structures.

This article will deal with installation and configuration of WebDAV server on Ubuntu Linux. WebDAV stands for Web Distributed Authoring and Versioning and allows connected users the edit and share data online via the HTTP protocol. This makes WebDAV a popular choice for developers when combined, for example, with Subversion or OpenLink Virtuoso. WebDAV is supported by number of clients ranging from davfs2, which makes it possible to mount the WebDAV's data storage to include into the local filesystem. This can be done with the mount command to various GUI applications with the native WebDAV support such as Nautilus, konqueror, etc.

This article will describe how to encrypt entire partition with a Cryptoloop. Cryptoloop is a disk encryption module for Linux. It was first introduced in the 2.5.x kernel series. Cryptoloop has an ability to create an encrypted file system on a single partition or within a regular file, which can later simply be mounted by the mount command. Cryptoloop uses so called loopback device, which needs to be called with any file system request. Currently there are many alternatives for Cryptoloop usage and the most common is Loop-AES. This article will explain a simple usage of the cryptoloop module for partition encryption and mounting within a Linux Operating system.

Whether you would like to share your code and data with other people or simply pack up your code in a concise way, the ability of building a custom package in GNU R may come useful to you. In this article we will outline as clearly as possible the process of building a basic package in R. This does not include more advanced knowledge on building R packages. This tutorial, however, will get you started.

MariaDB is an alternative choice for a database when professionals are looking for a robust, scalable, and reliable SQL server. It is an opensource drop-in replacement for the MySQL database and behaves in the exactly same way as MySQL. In this article we will install Joomla CMS with combination of the MariaDB database and the Apache2 webserver.

GNU R offers a wide variety of packages for its users. There are all kinds of packages for R, which allow to display graphics or perform statistical tests. Some packages are designed for applications specific to a given industry. Many packages are already a part of the basic R installation, however, some of them need to be additionally installed into GNU R. This article will describe how to install and use packages under R.

LEMP is an alternative to LAMP, the Linux based web server configuration stack using MySQL and PHP. However, instead of Apache LEMP is deployed with Nginx ( pronounced engine-x or en-juhn-eks ) web server. Nginx is a free, open-source, high-performance HTTP server and reverse proxy, which can be also used as a mail proxy. Nginx is acclaimed for having low memory usage and thus it is favored solution for a low RAM web server deployments such as VPS, etc. The difference in a memory consumption and serving speed between Apache and Nginx is likely to be noticeable under a heavy load. Thus, configuring Nginx should also help you to protect against sudden traffic spikes. However, the choice of using Ngnix over Apache is a matter of your environment where many aspects needs to be taken into the consideration. These are the content to be served, configuration settings, number of modules enabled, etc. In this tutorial we will setup a basic LEMP configuration on Ubuntu Linux.

Question2Answer (Q2A) is a popular open source Q&A solution, currently in use on thousands sites world-wide in 40 languages. It is built on the standard PHP/MySQL platform, and runs safe and fast. A Q&A engine helps you to create an online community to share knowledge. People with questions quickly get the answers they need. The community dynamic is enriched by commenting, voting, notifications, user points and rankings. In this guide we will show you how to install this popular software on Ubuntu LAMP.

In this quick GNU R tutorial to statistical models and graphics we will provide a simple linear regression example and learn how to perform such basic statistical analysis of data. This analysis will be accompanied by graphical examples, which will take us closer to producing plots and charts with GNU R. If you are not familiar with using R at all please have a look at the prerequisite tutorial: A quick GNU R tutorial to basic operations, functions and data structures.

Do you feel that someone is attempting to access you server? To find out, you can deploy a honeypot within your system to help you ease your paranoia by either confirming or dismissing your initial believe. As an example you can start the Kippo SSH honeypot, which allows you to monitor brute-force attempts, collect up today exploits and malware. Kippo also automatically records hacker's shell session, which you can replay to explore various hacking techniques and later use this gathered knowledge to harden your production server. Another reason why to install a honeypot is to take away an attention from your production server. In this tutorial we will show how to deploy a Kippo SSH honeypot on the Ubuntu server.

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.

If you ever wanted to have a personal robot then you are reading a correct article. This tutorial is a brief demonstration on how easily you can configure your personal or company robot, then soon after, connect it with one of available adapters like: shell, campfire, hipchat, irc, gtalk or skype. In this tutorial I'm going to teach you how to set up Hubot with its default adapter Shell. Although it's the simplest option, it's the solid foundation for your future modifications.

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.

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.

In the last two articles we have learned how to install and run GNU R on the Linux operating system. The purpose of this article is to provide a quick reference tutorial to GNU R that contains introduction to the main objects of the R programming language . We will learn about basic operations in R, functions and variables. Moreover, we will introduce R data structures, objects and classes.