Docker Commands

Working with Docker Images

Docker containers are built from Docker images. By default, Docker pulls these images from Docker Hub, a Docker registry managed by Docker, the company behind the Docker project. Anyone can host their Docker images on Docker Hub, so most applications and Linux distributions you’ll need will have images hosted there.

To check whether you can access and download images from Docker Hub, type:

docker run hello-world

The output will indicate that Docker in working correctly:

Unable to find image 'hello-world:latest' locally
latest: Pulling from library/hello-world
1b930d010525: Pull complete
Digest: sha256:41a65640635299bab090f783209c1e3a3f11934cf7756b09cb2f1e02147c6ed8
Status: Downloaded newer image for hello-world:latest

Hello from Docker!
This message shows that your installation appears to be working correctly.

Docker was initially unable to find the hello-world image locally, so it downloaded the image from Docker Hub, which is the default repository. Once the image downloaded, Docker created a container from the image and the application within the container executed, displaying the message. You can search for images available on Docker Hub by using the docker command with the search subcommand. For example, to search for the Ubuntu image, type: Continue reading “Docker Commands” »


Install Docker on Debain 10

Installing Docker

The Docker installation package available in the official Debian repository may not be the latest version. To ensure we get the latest version, we’ll install Docker from the official Docker repository. To do that, we’ll add a new package source, add the GPG key from Docker to ensure the downloads are valid, and then install the package.

First, update your existing list of packages:

sudo apt update

Next, install a few prerequisite packages which let apt use packages over HTTPS:

sudo apt install apt-transport-https ca-certificates curl gnupg2 software-properties-common

Then add the GPG key for the official Docker repository to your system: Continue reading “Install Docker on Debain 10” »


Install Netxtcloud on Debian 10

Install Apache, MariaDB and PHP

NextCloud runs on the webserver, written in PHP and uses MariaDB to store their data. So you will need to install Apache, MariaDB, PHP and other required packages on your system. You can install all of them by running the following command:

apt-get install apache2 libapache2-mod-php mariadb-server php-xml php-cli php-cgi php-mysql php-mbstring php-gd php-curl php-zip wget unzip -y

Once all the packages are installed, open the php.ini file and tweak some recommended settings:

nano /etc/php/7.3/apache2/php.ini

Change the following settings:

memory_limit = 512M
upload_max_filesize = 1024M
post_max_size = 1024M
max_execution_time = 300
date.timezone = Asia/Dhaka

Save and close the file when you are finished. Then, start the Apache and MariaDB service and enable them to start after system reboot with the following command: Continue reading “Install Netxtcloud on Debian 10” »


Redirect HTTP to HTTPs automatically in Zimbra 8.8

The most popular out of 5 options for proxy services, is to redirect. To do this, you can run the following as zimbra user:

zmprov ms `zmhostname` zimbraReverseProxyMailMode redirect

This will redirect your URLs to the zimbra hostname based HTTPs.

Now, restart the proxy services:

su - zimbra
zmproxyctl restart

Hope this helps.



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” »


Install ONLYOFFICE Document Server with Nginx on Debian 10

Step 1 – Install Packages Dependencies

In this first step, we will install some packages dependencies needed by the Document Server, including the RabbitMQ-server, Redis, and Nginx-extras.

Update your Debian system repository and install Document Server packages dependencies using the apt command below.

sudo apt update
sudo apt install redis-server rabbitmq-server nginx-extras gnupg2

Once all installation is complete, check the following services using the systemctl command as below.

systemctl is-enabled nginx
systemctl is-enabled rabbitmq-server
systemctl is-enabled redis-server

Now make sure all of these services are enabled and will automatically run on the system boot. Continue reading “Install ONLYOFFICE Document Server with Nginx on Debian 10” »


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” »


Upgrade Debian 9 to Debian 10

Update ALL existing installed packages

Before you upgrade your Debian version to 10, you must apply all security patches and pending upgrades to Debian 9 itself Hence, Type the following apt command or apt-get command:

sudo apt update
sudo apt upgrade
sudo apt full-upgrade
sudo apt --purge autoremove


sudo apt-get update
sudo apt-get upgrade
sudo apt-get full-upgrade
sudo apt-get --purge autoremove

Reboot the Debian 9.x stretch to apply the kernel and other updates: Continue reading “Upgrade Debian 9 to Debian 10” »


Softether Auto Installer on CentOS/Debian/Ubuntu (Backward compatible edition)

Softether Auto Install Script for multi platforms updated version

  • Softether VPN server latest version v4.27-9666-beta-2018.04.21
  • Revised to last known stable version due to compilation error from their latest release
  • An open source VPN project from University of Tsukuba Japan

Centos 6 or 7 x64

  • Debian 8 (jessie) (Not compatible for Debian 9 (stretch) x64 – compilation error)
  • Ubuntu 14, 15, 16 x64 (Not compatible for Ubuntu 17 and 18 x64 – compilation error)


Choose your desired platform folder

Download using wget or transfer to your root directory using ftp Continue reading “Softether Auto Installer on CentOS/Debian/Ubuntu (Backward compatible edition)” »


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” »