How to access EC2 instance if lost key Pair and root credentials

Step-1: 

Create a new instance with same OS as previous one or create it from AIM made from old instance

Step-2: 

Shutdown the old instance and detach the volume

Step-3: 

Shutdown new instance Attached the detached volume to new instance and start the instance

Step-4: 

Login new instance using ssh console

Run the following commands:

lsblk

df -h

cd mnt

mkdir oldvolume

sudo mount /dev/sda1 mnt/oldvolume

cd mnt/oldvolume/root/.ssh

sudo vi authorized_keys

Now add your public key and save 

umount /dev/sda1

sudo shutdown now

Step-5: 

Now detach the dev/sda1 volume from new instance and attach to old instance as dev/sda

Step-6:

Reboot old instance from AWS dashboard and login your old instance using ssh console 

 Note: Your old instance IP will be changed after doing this if no elastic IP

Install NVM (Node Version Manager) on macOS with Homebrew

Step - 1:

/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"
echo "# Homebrew\nexport PATH=/opt/homebrew/bin:\$PATH" >> .bash_profile

source ~/.bash_profile

or

/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"

echo "# Homebrew\nexport PATH=/opt/homebrew/bin:\$PATH" >> .zshrc
source ~/.zshrc

Step - 1:

brew update
brew install nvm
mkdir ~/.nvm

echo "export NVM_DIR=~/.nvm\nsource \$(brew --prefix nvm)/nvm.sh" >> .bash_profile
source ~/.bash_profile
or
echo "export NVM_DIR=~/.nvm\nsource \$(brew --prefix nvm)/nvm.sh" >> .zshrc
source ~/.zshrc

nvm install 12.13.0
nvm install --lts

How to install and run MongoDB GUI on Ubuntu 20.04

The following are the different ways to install mongo-gui.

From npm:

Install the module globally using the command :

npm install -g mongo-gui

Then use the command to run the application

mongo-gui 

From github:

First of all, clone the mongo-gui repository using the command git clone https://github.com/arunbandari/mongo-gui or download the zip file from here.

Change the directory to mongo-gui 

cd mongo-gui

Install all the dependencies npm install

Start the application using either 

npm start or node server.js 

Note: Node.js must be installed on your machine to run this application

From Docker Hub:

Docker compose

version: '3'

services:

  mongo-gui:

    container_name: "mongo-gui"

    image: ugleiton/mongo-gui

    restart: always

    ports:

      - "4321:4321"

    environment:

      - MONGO_URL=mongodb://localhost:27017

Mongo GUI Usage

The commands mongo-gui and npm start or node server.js start the application with the following configuaration:

URL (-u): mongodb://localhost:27017

PORT (-p): 4321

and the application will be accesible at http://localhost:4321

To connect to any other mongodb instance, pass mongo connection string as an argument, eg:

Installed via npm: mongo-gui -u mongodb+srv://<username>:<password>@host/<dbnames>?retryWrites=true&w=majority'

Installed via github: (npm start --/node server.js) -u mongodb+srv://<username>:<password>@host/<dbnames>?retryWrites=true&w=majority'

Available options:

-u: url, mongo-gui tries to connect to this mongodb instance

-p: port, mongo-gui listens on this port

Failed to start mongod.service: Unit mongod.service not found Solved !

When I started MongoDB got an error as:

"Failed to start mongod.service: Unit mongod.service not found."

Check port and configuration

sudo nano /etc/mongod.conf

Solution:

sudo systemctl unmask mongod

and re-run

sudo service mongod start

sudo service mongod status

sudo systemctl enable mongod

sudo service mongod restart

service mongod stop
#dont start mongod…instead…

systemctl start mongod
#then mongo command

#then

mongo




How to install composer and use it on Ubuntu

sudo apt update

sudo apt install wget php-cli php-zip unzip

wget -O composer-setup.php https://getcomposer.org/installer

sudo php composer-setup.php --install-dir=/usr/local/bin --filename=composer

sudo php composer-setup.php --install-dir=/path/to/project

sudo composer self-update  

composer require nesbot/carbon

Install multiple PHP version on Ubuntu for Virtualmin

 Enable ondrej/php repository

LC_ALL=C.UTF-8 add-apt-repository -y ppa:ondrej/php && apt-get update

Install additional PHP packages

apt-get install php*-{cgi,cli,fpm,pdo,gd,mbstring,mysqlnd,opcache,xml,zip} 

Note: php* should be replaced with a specific PHP version, i.e. php7.4, unless you really need to install all available additional PHP versions.

Configuring the second PHP Version in Virtualmin

Once you have completed the installation of a second PHP version on your server, you can verify that Virtualmin sees it by logging into Virtualmin, and clicking System Settings → Re-Check Config. You should see something like this:

The following PHP execution modes are available : fpm
The following PHP-FPM versions are available : 8.0.13 (php-fpm) 7.4.30 (php74-php-fpm) 8.2.0 (php82-php-fpm) 

You can configure which one is the default PHP version used on new Virtual Servers. The default is to use the newest available. You can change that default in System Settings → Server Templates → Default → PHP Options page.

Configuring Individual Virtual Servers

You can configure the PHP version being used for a specific Virtual Server by selecting Server Configuration → PHP Options.

Source: https://www.virtualmin.com/documentation/web/multiplephp/

How to Install Apache2 to make Web Server on Ubuntu 20.04

 sudo apt update

sudo apt install apache2

sudo systemctl is-active apache2

sudo systemctl is-enabled apache2

sudo systemctl status apache2

sudo systemctl stop apache2      #stop apache2

sudo systemctl start apache2     #start apache2

sudo systemctl restart apache2   #restart apache2

sudo systemctl reload apache2    #reload apache2

sudo systemctl disable apache2   #disable apache2

sudo systemctl enable apache2    #enable apache2

ls /etc/apache2/*

sudo vim /etc/apache2/apache2.conf 

ServerName webserver1.tecmint.com

sudo apache2ctl configtest

sudo systemctl restart apache2

sudo systemctl status apache2

sudo ufw allow http

sudo ufw allow https

sudo ufw reload

OR

sudo ufw allow 80/tcp

sudo ufw allow 443/tcp

sudo ufw reload

ls /var/www/html/

sudo mkdir -p /var/www/html/olineit.info

sudo chown www-data:www-data -R /var/www/html/olineit.info

sudo chmod 775 -R /var/www/html/olineit.info

sudo vim /var/www/html/olineit.info/index.html

sudo vim /etc/apache2/sites-available/olineit.info.conf

sudo a2ensite olineit.info.conf

sudo systemctl reload apache2