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” »


How to fix CentOS 5 or 6 error: YumRepo Error: All mirror URLs are not using ftp, http[s] or file

The error looks like-

And here goes the resolution (please carefully update/use the exact CentOS version you are using, in my case it was CentOS 6.9)

1. Go to /etc/yum.repos.d/ directory:

# cd /etc/yum.repos.d/

2. Make copy of original file:

# cp CentOS-Base.repo CentOS-Base.repo.old

3. Open and edit file with any text editor:

# vi CentOS-Base.repo looks

4. After editing it should looks like: Continue reading “How to fix CentOS 5 or 6 error: YumRepo Error: All mirror URLs are not using ftp, http[s] or file” »


Build a Centos 7 Repo

Install httpd

[root@www ~]# yum -y install httpd
# remove welcome page
[root@www ~]# rm -f /etc/httpd/conf.d/welcome.conf

Configure httpd. Replace server name to your own environment.

[root@www ~]# vi /etc/httpd/conf/httpd.conf
# line 86: change to admin's email address

# line 95: change to your server's name

# line 151: change

AllowOverride All
# line 164: add file name that it can access only with directory's name

DirectoryIndex index.html index.cgi index.php
# add follows to the end

# server's response header

ServerTokens Prod
# keepalive is ON

KeepAlive On

[root@www ~]# systemctl start httpd
[root@www ~]# systemctl enable httpd

Install other required packages.

[root@dlp ~]# yum -y install rsync createrepo

Continue reading “Build a Centos 7 Repo” »


Install MariaDB on CentOS 7

Start by adding the MariaDB YUM repository file MariaDB.repo for RHEL/CentOS and Fedora systems.

# vi /etc/yum.repos.d/MariaDB.repo

Now add the following lines to your respective Linux distribution version as shown.

On CentOS 7
name = MariaDB
baseurl =

Step 2: Install MariaDB in CentOS 7
Once MariaDB repository has been added, you can easily install it with just one single command.

# yum install MariaDB-server MariaDB-client -y

Continue reading “Install MariaDB on CentOS 7” »


Install WHMCS on CentOS 7

As you may know, WHMCS is the leading web hosting management and billing software that automates all aspects of your business from billing, provisioning, domain reselling and etc. In this article, we are going to install WHMCS 7.7.1 on CentOS 7.6.

We assume you have a valid WHMCS license and have downloaded its package from WHMCS download area.

Here are our environment OS and software versions:

  • OS: Centos 7.6 on VMware
  • WHMCS: 7.7.1
  • PHP: 7.2
  • Database: Mariadb 10.3
  • Web server: httpd 2.4

Here we start from a fresh minimal CentOS 7.6 installation.

1- Initial CentOS setup
Set correct time and date. here we use “Asia/Dhaka”:

# timedatectl set-timezone America/New_York

Change default root password:

# passwd

Set SELinux to permissive mode by editing /etc/selinux/config:

# vim /etc/selinux/config

Also to apply it immediately run: Continue reading “Install WHMCS on CentOS 7” »


Configuring SpamAssassin for Postfix on CentOS

In the process of receiving email, spamassassin will stand between the outside world and the email services running on your server itself. If it finds, according to its definition rules and configuration, that an incoming message is spam, it will rewrite the subject line to clearly identify it as such. Let’s see how.

The main configuration file is /etc/mail/spamassassin/, and we should make sure the following options are available (add them if they are not present or uncomment if necessary):
report_safe 0
required_score 8.0
rewrite_header Subject [SPAM]

When report_safe is set to 0 (recommended value), incoming spam is only modified by modifying the email headers as per rewrite_header. If it is set to 1, the message will be deleted. To set the aggressivity of the spam filter, required_score must be followed by an integer or decimal number. The lesser the number, the more sensitive the filter becomes. Setting required_score to a value somewhere between 8.0 and 10.0 is recommended for a large system serving many (~100s) email accounts. Once you’ve saved those changes, enable and start the spam filter service, and then update the spam rules: Continue reading “Configuring SpamAssassin for Postfix on CentOS” »


Install ClamAV on CentOS 6

Step 1. First add yum repository your system.

The EPEL repo is enabled by simply installing an RPM. Please use the command below to install the EPEL repository on your CentOS server.

#CentOS 6 – 32-bit

rpm -Uvh

#CentOS 6 – 64-bit

rpm -Uvh

Step 2. Install required ClamAV packages.

yum install clamav clamd

Step 3. Start the clamd service on system boot. Continue reading “Install ClamAV on CentOS 6” »


Install SNMP and Configure the Community String For CentOS

Install SNMP

Install the SNMPD service by running the following command:

yum install net-snmp net-snmp-utils

Once the service is installed, verify that it is set to start at startup by running:

CentOS 6:

chkconfig snmpd on

CentOS 7:

systemctl enable snmpd

Continue reading “Install SNMP and Configure the Community String For CentOS” »