Install SmokePing on CentOS 7

This tutorial explains how to install Tobias Oetiker’s Smokeping into /opt/smokeping on a CentOS 7 box.

Features of Smokeping:
– Best of breed latency visualisation.
– Interactive graph explorer.
– Wide range of latency measurement plugins.
– Master/Slave System for distributed measurement.
– Highly configurable alerting system.
– Live Latency Charts with the most ‘interesting’ graphs.
– Free and open-source Software written in Perl written by Tobi Oetiker, the creator of MRTG and RRDtool Continue reading “Install SmokePing on CentOS 7” »


Cloning KVM virtual machine using CLI

To clone your VM and spawn new instances in KVML

# virt-clone --original {Domain-Vm-Name-Here} --auto-clone


# virt-clone --original {Domain-Vm-Name-Here} --name {New-Domain-Vm-Name-Here} --auto-clone


# virt-clone --original {Domain-Vm-Name-Here} \
--name {New-Domain-Vm-Name-Here} --file {/var/lib/libvirt/images/}

Continue reading “Cloning KVM virtual machine using CLI” »


Install and Secure Redis on CentOS 7

Step 1 – Install and Enable Remi Repository

Firstly, we will add the Remi repository to the CentOS 7 system. The Remi repository provides the latest version of Redis package for our installation.

Before adding the Remi repository, let’s install the EPEL repository and yum utility packages.

sudo yum install epel-release yum-utils

Now add the Remi repository for CentOS 7 using the yum command below.

sudo yum install

After that, enable the ‘remi’ repository using the yum-config-manager tool as below.

sudo yum-config-manager --enable remi

The Remi repository has been added and enabled on the CentOS 7 system, check using the yum command Continue reading “Install and Secure Redis on CentOS 7” »


Install MongoDB on CentOS 7

Follow the steps below to install the latest stable version of MongoDB on your CentOS server :

Enabling MongoDB repository

To add the MongoDB repository to your system, open your text editor and create a new YUM repository configuration file named mongodb-org.repo inside the /etc/yum.repos.d/ directory:

nano /etc/yum.repos.d/mongodb-org.repo
name=MongoDB Repository

If you want to install an older version of MongoDB, replace each instance of 4.0 with your preferred version. Continue reading “Install MongoDB on CentOS 7” »


CentOS 7 XFS disk resizing

Couldn’t find any article that explained step by step how to resize the main disks volume in a CentOS 7 vm. In my example I started witha single disk of 8GB and expanded to 20GB. I have two partitions on disk sda

sda1 type Linux for boot
sda2 type Linux LVM for the remaining logical volumes

Space utilisation as following:

[root@vcd-c1-s1 ~]# df -h
Filesystem Size Used Avail Use% Mounted on
devtmpfs 3.9G 0 3.9G 0% /dev
tmpfs 3.9G 0 3.9G 0% /dev/shm
tmpfs 3.9G 8.8M 3.9G 1% /run
tmpfs 3.9G 0 3.9G 0% /sys/fs/cgroup
/dev/mapper/centos-root 6.2G 1.9G 4.4G 31% /
/dev/sda1 1014M 179M 836M 18% /boot
tmpfs 783M 0 783M 0% /run/user/0

We basically need to: Continue reading “CentOS 7 XFS disk resizing” »


Install webmin on Centos 7 using Yum

Create and open this new file using your text editor:

sudo vi /etc/yum.repos.d/webmin.repo

Then add these lines to the file to define the new repository:

nano /etc/yum.repos.d/webmin.repo
name=Webmin Distribution Neutral

Save the file and exit the editor. Continue reading “Install webmin on Centos 7 using Yum” »


Upgrade Python 2.7 to 3.6 and installing pip on CentOS 7

Installing Development Tools

Development tools are required for building Python modules. To install the necessary tools and libraries type:

sudo yum groupinstall 'Development Tools'

Enable Software Collections (SCL)

Software Collections , also known as SCL is a community project that allows you to build, install, and use multiple versions of software on the same system, without affecting system default packages. By enabling SCL you will gain access to the newer versions of programming languages and services which are not available in the core repositories.

CentOS 7 ships with Python 2.7.5 which is a critical part of the CentOS base system. SCL allows you to install newer versions of python 3.x alongside the default python v2.7.5 so that system tools such as yum will continue to work properly.

To enable SCL, you need to install the CentOS SCL release file. It is part of the CentOS extras repository and can be installed by running the following command:

sudo yum install centos-release-scl

Continue reading “Upgrade Python 2.7 to 3.6 and installing pip on CentOS 7” »


Install wkhtmltopdf 0.12.5 on Centos 7

Install Dependencies

yum install fontconfig libXext freetype libpng zlib libjpeg-turbo libpng libjpeg openssl icu libX11 libXext libXrender xorg-x11-fonts-Type1 xorg-x11-fonts-75dpi

Install wkhtmltopdf

sudo yum install -y


wkhtmltopdf google.pdf


Configure DomainKeys- DKIM (OpenDKIM) with Postfix on CentOS 7

OpenDKIM is method to digitally sign & verify emails on the mail servers using public & private keys. In other words opendkim implements the DKIM (DomainKeys Identified Mail) standard for signing and verifying email messages on a per-domain basis. DomainKeys are implemented to reduce the chances of outgoing mails to be marked as SPAM.

In this post we will demonstrate how to install & configure DomainKeys with postfix (MTA) on CentOS 7, i am assuming Postfix is already installed with following domain and hostname.

Hostname =
Domain =

Step:1 Set EPEL Repository using below rpm command

OpenDKIM package is not available in the default yum repositories but available in CentOS 7 EPEL repositories

[root@mail5 ~]# rpm -Uvh

Step:2 Install OpenDKIM Package using yum

[root@mail5 ~]# yum install -y opendkim

Step:3 Run below Command to create keys

Execute the below command to create public & private keys under folder “/etc/opendkim/keys” Continue reading “Configure DomainKeys- DKIM (OpenDKIM) with Postfix on CentOS 7” »


Setup mail server on centos 7 using postfix and dovecot

Installing packages

Step 1 » Assign hostname for the server using the below command.

[root@krizna ~]# hostnamectl set-hostname

Step 2 » Make a host entry with your IP in /etc/hosts file.

Step 3 » Now start installing packages.

[root@krizna ~]# yum -y install postfix dovecot

After package installation continue with postfix configuration. Continue reading “Setup mail server on centos 7 using postfix and dovecot” »