Objective

The objective of this guide is to provide you with some hints on how to check system version of your Redhat Enterprise Linux (RHEL). There exist multiple ways on how to check the system version, however, depending on your system configuration, not all examples described below may be suitable. For a CentOS specific guide visit How to check CentOS version guide.

Requirements

Privileged access to to your RHEL system may be required.

Difficulty

EASY

Conventions

Install or upgrade PHP 7 on CentOS 7 Linux server

Objective

The objective is to install or replace existing PHP 5 with PHP 7 on CentOS 7 Linux server. As you will see, this procedure is fairly simple when using Remi Repository.

Requirements

Privileged access to your CentOS Linux system either directly as root user or via sudo command is required.

Difficulty

EASY

Conventions

  • # - requires given linux commands to be executed with root privileges either directly as a root user or by use of sudo command
  • $ - requires given linux commands to be executed as a regular non-privileged user

Instructions

The following guide will either upgrade your current PHP 5 to PHP 7 or will install new PHP 7 on your CentOS system. Check your current PHP version ( if applicable ):
# php --version
PHP 5.4.16 (cli) (built: Nov  6 2016 00:29:02) 
Copyright (c) 1997-2013 The PHP Group
Zend Engine v2.4.0, Copyright (c) 1998-2013 Zend Technologies

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Download Remi and EPEL Repository packages

First, download Remi and EPEL Repository packages:
$ wget -q http://rpms.remirepo.net/enterprise/remi-release-7.rpm
$ wget -q https://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm

Introduction

Popcorn Time streams movies and TV shows from torrents directly into your screen.

Objective

The objective is to install Popcorn Time player on CentOS 7.

Requirements

Optional privileged access to your CentOS is required if system-wide installation is required.

Difficulty

EASY

Conventions

  • # - requires given linux commands to be executed with root privileges either directly as a root user or by use of sudo command
  • $ - requires given linux commands to be executed as a regular non-privileged user

Instructions

Prerequisites

First install some tools to be used for the Popcorn Time installation:
# yum install wget xz

Popcorn Time Installation

Please note that, if you experience the bellow error message with version 0.3.10, try to install older Popcorn Time version.
Illegal instruction (core dumped)

Popcorn Time Version 0.3.9

32-bit
# mkdir /opt/popcorn-time; wget -qO- https://get.popcorntime.sh/build/Popcorn-Time-0.3.9-Linux-32.tar.xz | unxz | tar x -C /opt/popcorn-time
# ln -sf /opt/popcorn-time/linux64/Popcorn-Time /usr/bin/popcorn-time

Objective

The the network command line tool ifconfig is not installed thus missing by default on CentOS 7 Linux. Users are instead encouraged to use ip command to do most of the network administration work.

For example the following ip command can be used to show IP address on CentOS 7:
# ip address show
OR SIMPLY
# ip a s
1: lo:  mtu 65536 qdisc noqueue state UNKNOWN 
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: eth0:  mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether f2:d9:fc:79:72:d7 brd ff:ff:ff:ff:ff:ff
    inet 10.1.1.145/8 brd 10.255.255.255 scope global dynamic eth0
       valid_lft 861944sec preferred_lft 861944sec
    inet6 fe80::f0d9:fcff:fe79:72d7/64 scope link 
       valid_lft forever preferred_lft forever
3: virbr0:  mtu 1500 qdisc noqueue state DOWN 
    link/ether 52:54:00:e3:e3:3e brd ff:ff:ff:ff:ff:ff
    inet 192.168.122.1/24 brd 192.168.122.255 scope global virbr0
       valid_lft forever preferred_lft forever
4: virbr0-nic:  mtu 1500 qdisc pfifo_fast master virbr0 state DOWN qlen 500
    link/ether 52:54:00:e3:e3:3e brd ff:ff:ff:ff:ff:ff
However, it is still possible to use the old-fashioned ifconfig command. Thus our objective is to install ifconfig on CentOS 7 Linux which is a part of net-tools package.

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Requirements

Privileged access to your CentOS 7 Linux server/desktop.

Difficulty

EASY

Conventions

  • # - requires given linux commands to be executed with root privileges either directly as a root user or by use of sudo command
  • $ - requires given linux commands to be executed as a regular non-privileged user

Instructions

CentOS 7 ifconfig install

Execute the following yum command in order to install ifconfig on CentOS 7:
# yum install net-tools

Objective

The objective is to install Docker engine on Redhat 7 Linux using native docker script.

Requirements

Internet connection as well as a privileged access to your Redhat 7 Linux is required.

Difficulty

EASY

Conventions

  • # - requires given linux commands to be executed with root privileges either directly as a root user or by use of sudo command
  • $ - requires given linux commands to be executed as a regular non-privileged user

Instructions

Install docker

Installation of docker using a native docker script is one command, straight forward process. Before you run the below docker installation command ensure that curl package is installed on your system:
# curl --version
curl 7.29.0 (x86_64-redhat-linux-gnu)

Introduction

Unbound is a validating, recursive, and caching DNS server. Having said that, Unbound DNS server cannot be used as an authoritative DNS server, which means it cannot be used to host custom domain name records. As a result, if your goal is to build a cache-only or forwarding DNS server, Unbound may be your preferred choice, as it does just that and it does it well.

Objective

The objective is to provide quick and easy to follow installation and configuration guide for the Unbound cache-only DNS server on Redhat 7 Linux. At the end of this guide you will be able to use Unbound DNS server from all clients on your local area network.

Requirements

Privileged access to your Redhat 7 Linux server with configured standard RedHat repositories.

Difficulty

MEDIUM

Conventions

  • # - requires given linux commands to be executed with root privileges either directly as a root user or by use of sudo command
  • $ - requires given linux commands to be executed as a regular non-privileged user

Instructions

Unbound and DNS tools installation

In the first step we are going to install the actual Unbound DNS server as well as DNS tools which will be eventually used to test your DNS cache-only server configuration. Given that you have your Redhat repository configured correctly you can install both by executing the following linux command:
# yum install unbound bind-utils

Objective

The objective is to permanently disable a last login message after user terminal or ssh login on Redhat Linux. Example:
$ ssh This email address is being protected from spambots. You need JavaScript enabled to view it.
This email address is being protected from spambots. You need JavaScript enabled to view it.'s password: 
Last login: Tue Dec  6 11:23:11 2016 from 10.1.1.3
rhel linux last login message disable or clear

Requirements

Privileged access to your Redhat Linux server.

Difficulty

EASY

Conventions

  • # - requires given linux commands to be executed with root privileges either directly as a root user or by use of sudo command
  • $ - requires given linux commands to be executed as a regular non-privileged user

Instructions

Single user

To permanently suppress a Last Login message as per on user basis, create a hidden .hushlogin file inside a user's home directory. For example to suppress a Last Login message for a linuxconfig user run:
# touch /home/linuxconfig/.hushlogin

Objective

By default the regular user does not have an ability to execute commands with root privileges. As a result the following message will appear:
$ sudo -i
[sudo] password for linuxconfig: 
linuxconfig is not in the sudoers file.  This incident will be reported.
redhat 7 user not in sudoers file
The objective is to gain a superuser ( root ) access on Redhat 7 Linux server using sudo command.

Requirements

Privileged root access to your Redhat 7 Linux server installation.

Difficulty

EASY

Conventions

  • # - requires given linux commands to be executed with root privileges either directly as a root user or by use of sudo command
  • $ - requires given linux commands to be executed as a regular non-privileged user

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Instructions

Add user to WHEEL group

Using your current shell or log in as a root user execute the following linux command to add any user you wish to grant a sudo access. The example below will give a sudo access to linuxconfig user:
# usermod -G wheel linuxconfig

Objective

The objective is to instruct Gnome Desktop Manager to automatically login a specified system user.

Requirements

Privileged access to your CentOS 7 installation and existing user account to enable Automatic login upon.

Difficulty

EASY

Conventions

  • # - requires given linux commands to be executed with root privileges either directly as a root user or by use of sudo command
  • $ - requires given linux commands to be executed as a regular non-privileged user

Instructions

Update GDM settings

Add the following stanza into a [daemon] section of your /etc/gdm/custom.conf while replacing keyword "linuxconfig" with a username of your autologin user:
[daemon]
AutomaticLogin=linuxconfig
AutomaticLoginEnable=True

Objective

The objective is to install KDE desktop environment on a minimal CentOS 7 installation.

Requirements

Privileged access to CentOS 7 system installation and Internet access or configured local CentOS 7 package repository. Furthermore, the guide assumes that you have already performed a CentOS 7 Linux installation.

Difficulty

EASY

Conventions

  • # - requires given linux commands to be executed with root privileges either directly as a root user or by use of sudo command
  • $ - requires given linux commands to be executed as a regular non-privileged user

Instructions

Install Group packages

Use yum command to install KDE and X Window System group packages
# yum groupinstall 'KDE' 'X Window System'

Objective

Resetting the root password in RHEL7/CentOS7/Scientific Linux 7

Requirements

RHEL7 / CentOS7 / Scientific Linux 7

Difficulty

MODERATE

Instructions

Things have changed in the RHEL7 world and so has the preferred way of resetting the root password. Although the old way of interrupting the boot process (init=/bin/bash) still works, it is no longer bulletproof and recommended. 'Systemd' uses 'rd.break' to interrupt the boot. Let's have a quick walk through the whole procedure.

Introduction

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.

Using Official Redhat DVD as repository

After default installation and without registering your server to official RHN repositories your are left without any chance to install new packages from redhat repository as your repository list will show 0 entries:

# yum repolist
Loaded plugins: product-id, refresh-packagekit, security, subscription-manager
This system is not registered to Red Hat Subscription Management. You can use subscription-manager to register.
repolist: 0

Symptoms

Any attempt to play video will result in an error:
Movie Player requires additional plugins to decode this file. The following plugins are required : MPEG-4-AAC decoder and H.264 decoder
The following plugins are required : MPEG-4-AAC decoder and H.264 decoder - CentOS 7
The offered help for search also fails.

This guide will discuss a procedure on how to connect/establish a VPN connection using PPTP protocol on CentOS 7 or Redhat 7 Linux the non-GUI way. Below you can find connection details which will be used as an example. Replace the bellow PPTP VPN information to align with your PPTP VPN server settings:
  • Connection name: linuxconfig ( can be any descriptive name )
  • VPN connetion type: PPTP
  • PPTP VPN server IP or domain: 123.123.1.1
  • CHAP Username: admin
  • CHAP User password: 00000000

Configuration

Let's begin by installation of PPTP client:
# yum install pptp

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