How to Add/Remove Yum Repositories

Red Hat Enterprise Linux, CentOS, Fedora and other Linux distributions based on RHEL all use YUM as a package management system to install, remove, and update software. Each distribution has its own main repository, but you can also install or remove third-party repositories whenever you like.
To add a YUM repository, type as root:
yum-config-manager –add-repo repository_url
For […]

Understanding Systemd and How to Use It: Part 1

Systemd has gradually made a name for itself in the Linux world and is or will eventually be the default service management system for a number of major Linux distributions. Those accustomed to the old init systems will not find Systemd to be horribly complex, but it does feature some significantly different approaches to service […]

How to Configure Linux Password Policies

One of your best weapons in the fight for server security is strong password management. Using the password policies you set in Linux, you enforce strong passwords, require password renewals and many other effective security measures.
First, you should install the cracklib module for PAM. Cracklib tests password strength. If you are using RHEL, CentOS or […]

How to Remove Old Linux Kernels

Linux distributions that use binary packages usually install kernel updates in separate directories from previous kernel versions. Therefore, it is possible to have several instances of Linux installed within the same system. This is a precaution that prevents you from overwriting your kernel with one that may not function the way you want, or at […]

How to View Hardware Information on a Linux Server

Have you ever found yourself in a situation that required you to find out some information about your server’s hardware and did not have the documentation handy? In some cases, the documentation may even be too generic, covering multiple models. In such a circumstance, you can either crack open the server and take a peek […]

Encrypt Your Linux Server Filesystem with eCryptfs

Encryption has become a highly requested feature on the web lately with all of the talk of government spying, heartbleed and general security concerns. While most discussion has centered around encrypting the transport of data (via SSL), you might also want your data encrypted on disk as well. On a Linux-based server, you can encrypt […]

Should I Use CentOS for Business?

If you ask someone at Red Hat about CentOS, they will likely tell you that it is a great “community” distribution, but for enterprise servers, you need Red Hat Enterprise Linux and the support that comes with it. This is their job, of course, to promote their own software, but there is also some truth […]

Setup and Configure CentOS Server Part 2

In part one, we began by changing the root password and then creating an account that will be able to escalate to root privileges when needed. Now, you need to make sure that only that user can become root and not anyone else.
The easiest way to do this is to use the “wheel” group. You […]

How to Update Your OpenSSL Version to Fix Heartbleed Bug

Heartbleed, the highly publicized OpenSSL bug with the unfortunate name, has a lot of system administrators scurrying to fix the problem. If you have not heard about it by now, it is a security hole found in OpenSSL’s TLS heartbeat extension that a cyber criminal can use to reveal 64k of memory on a connected […]

Setup and Configure CentOS Server Part 1

CentOS is essentially a free implementation of the open source code from Red Hat Enterprise Linux. Logos and other trademarks aside, CentOS is RHEL at its core without the licensing fees. As such, CentOS has become very popular among server administrators as an ideal Linux server solution. This brief tutorial will explain how to get […]

Linux OS Reboot and Service Restart Guide

Your brand new Linux server may seem a bit intimidating at first, but with a little training and practice, you will find it to be very manageable. The following is a quick guide to restarting services and your OS itself.
Reboot – Rebooting your server is quite simple. On the console, you can press CTRL+ALT+Delete. If […]

Use VLC to Stream Live Media

You do not have to pay big money to stream video or audio over the Internet. If you already have a dedicated server or VPS, you can use VLC to stream media to your users.
VLC is a free and open source video player and streaming media server. On the client side, you can use it […]

How to Fix Out of Memory Script Errors

A common problem you might face when running PHP scripts is an “out of memory” error. It usually looks something like this:
PHP Fatal error: Out of memory (allocated 51795435) (tried to allocate 84524 bytes) in /home/user/public_html/randomdirectory/file.php on line 750
First, it is important to understand what this error means. PHP is configured to only allow a […]

Speed Up Your Web Applications with Memcached

Most modern websites are dynamic in nature. They are updated on the fly, rely on database backends and often feature some type of support for user interaction. While those aspects of dynamic websites are all positive, the negative side is that they require more system resources, especially memory. A more resource-intense web application can slow […]

4 Free OpenVZ Control Panels

OpenVZ is free and open source virtualization software that gives you the ability to create and manage virtual private server containers on your dedicated server. While you could manage it quite effectively from the command line, you may prefer to use some type of hosting automation system. The following are some free web-based management tools […]

How to Manually Install Packages on a RHEL/CentOS Server

On Red Hat Enterprise Linux and Red Hat-based servers (ex: CentOS), the best way to install packages is to use YUM. By entering the yum command, you can download and install software from the distribution and third-party repositories without any difficulty. On occasion, however, you might need to install an rpm package that is not […]

Do I Need A Commercial Linux Distribution?

Your shiny new server is just begging for an operating system or perhaps even two or three, if you intend to use virtualization. You might have already decided to use a Linux-based operating system, which is popular for Internet-connected servers. What you might still need to decide, however, is whether to use a community distribution […]

How to Apply Apache Configuration Changes Gracefully

From time to time, you may need to make changes to your Apache HTTP Server configuration file, especially if you are optimizing your web server for performance. Once you have completed changes, they will not come into effect until you restart your web server. This, however, would mean downtime, however briefly, for […]

How to Install OpenVZ on CentOS

CentOS is one of the most popular free and open source server operating systems. OpenVZ is a popular open source system for creating virtual private servers. Combine the two together, and you have a low-cost yet powerful VPS system. The following is a brief installation guide to get OpenVZ running on CentOS.
Step 1. Add […]

What to Expect from a VPS Provider

Most web hosting companies offer some form of VPS service, so it can be difficult to decide which one is right for you. A virtual private server can be almost anything that uses virtualization, so it is important to know what you are getting and if the services offered fit your needs. These are some […]

What Are Shadow Passwords?

On a basic Linux system, passwords are stored in the /etc/passwd file. This is usually OK for a single-user system, but on a multi-user system, such as a server, the passwords should be hidden and encrypted. Shadow passwords allow you to do just that . On Red Hat Enterprise Linux and CentOS, the shadow-utils package […]

Linux Server Security Guide: Part 1

Over the years at Dedicated Server School, we have provided you with numerous security tips, often on an individual and specific level. This five-part series will instead give a general overview of Linux server security to serve as a quick reference tool whenever you might need it. Rather than searching for the security topic you […]

Server OS Profile: CentOS

Sometimes you need enterprise-level software but cannot afford the enterprise-level price. Such is often the case with dedicated servers. Many individuals and companies operate on a limited budget and cannot afford to pay for licensing and support for an enterprise server OS such as Red Hat Enterprise Linux. Others simply may not need the paid […]

Server OS Profile: Red Hat Enterprise Linux

For many years, some people believed it was impossible for a free and open source operating system like Red Hat Linux to be profitable. With the formulation of Red Hat Enterprise Linux, the company Red Hat proved that theory wrong and also established Linux as one of the most widely-used Unix server alternatives. It now […]

Linux Terminology You Should Know

Continuing our series on server-related terminology, Linux terminology seems to be a sensible choice. Many of the world’s servers run Linux, especially in the web hosting industry, and a great deal of the terminology common to Linux may be unfamiliar to users who use Windows. The following terms are ones you should know.
Kernel – This […]

Server Terminology You Should Know

SSH – Secure Shell allows you to connect to your server as though you were sitting in front of it typing on the console. If you have administrative access, you can completely control your server from SSH. Connections made via SSH are also encrypted and secure.
Apache HTTP Server – The most popular web server software […]

3 Ways to Configure Services to Start at Boot in CentOS: Part 2

In part 1 of this series, you learned how to use the command line interface (CLI) and a program called chkconfig to configure services to start at boot on a Linux dedicated server. In this part, you will learn how to use the unique Red Hat “Setup” utility and Webmin’s web-based control panel […]

How to Run Virtualbox in “Headless” Mode

In previous posts, we learned how to use Virtualbox to create a virtual machine, install a guest operating system, and then use the VM as a test server. Now that you know how to make a test server, you might want to know how to run it on a […]

How to Connect to a Virtualbox VM Via SSH (Part 1)

In some previous posts, you learned how to setup a Virtualbox virtual machine (VM) for the purpose of creating a test server environment. Once you have a functioning test server, you are free to always work on it within the virtual machine, but if you ever want to connect to it remotely, you probably soon […]

How to Disable a Firewall on RHEL/CentOS

It is generally not a good idea to disable the firewall on your dedicated server, but there are instances when it might be necessary. For example, if you need to run some network tests or perform some type of maintenance, you may need to have your firewall disabled. Most Linux distributions come with the standard […]