How To Make secured Nginx with Let's Encrypt on Ubuntu

 Installing Certbot:

sudo apt install certbot python3-certbot-nginx

Confirming Nginx’s Configuration:

sudo nano /etc/nginx/sites-available/example.com

sudo nginx -t

sudo systemctl reload 

Allowing HTTPS Through the Firewall:

sudo ufw status

sudo ufw allow 'Nginx Full'

sudo ufw delete allow 'Nginx HTTP'

sudo ufw status

Obtaining an SSL Certificate:

sudo certbot --nginx -d example.com -d www.example.com

 Verifying Certbot Auto-Renewal:

 sudo systemctl status certbot.timer

 sudo certbot renew --dry-run

How to change Folder and File Permission in Linux

sudo find /var/www/html -type d -exec chmod 755 {} \;

sudo find /var/www/html -type f -exec chmod 644 {} \;

sudo chmod 644 /var/www/html/textbook.php

sudo chmod 644 /var/www/html/textbook.php


sudo systemctl restart httpd

Debian/Ubuntu Linux Specific Commands to Start/Stop/Restart Apache Engine

Debian Linux version 7.x or Ubuntu Linux version Ubuntu 14.10 or older:

Restart:

/etc/init.d/apache2 restart

sudo /etc/init.d/apache2 restart

sudo service apache2 restart

Stop
/etc/init.d/apache2 stop

sudo /etc/init.d/apache2 stop

sudo service apache2 stop

/etc/init.d/apache2 start

sudo /etc/init.d/apache2 start

sudo service apache2 start

Debian Linux version 8.x+ or Ubuntu Linux version Ubuntu 15.04+ or above:

sudo systemctl start apache2.service

sudo systemctl stop apache2.service

sudo systemctl restart apache2.service

sudo systemctl status apache2.service

CentOS/RHEL (Red Hat) Linux version 4.x/5.x/6.x:

## Start ##

service httpd start

## Stop ##

service httpd stop

## Restart ##

service httpd restart

CentOS/Fedora/RHEL (Red Hat) Linux version 7.x or newer:

## Start command ##

sudo systemctl start httpd.service

## Stop command ##

sudo systemctl stop httpd.service

## Restart command ##

sudo systemctl restart httpd.service

Alpine Linux:

service apache2 start

service apache2 stop

service apache2 status

service apache2 restart

Two-Factor Authentication (2FA) for Webmin with Google Authenticator

First install Perl Modules :

https://blog.olineit.com/2022/09/install-perl-cpan-module-in-centos-8.html

Then follow the instructions as given through the URL:

https://devtutorial.io/how-to-install-two-factor-authentication-2fa-for-webmin-p2845.html

Install Perl CPAN Module in CentOS 8

dnf install perl-CPAN

dnf install "@Development Tools"

perl -MCPAN -e 'install Authen::OATH'

cpan -i Geo::IP OR 

cpan Geo::IP

cpan 

cpan[1]> install Log::Log4perl

OR

You need gcc.:

yum install gcc

Get CPAN:

yum install CPAN

Configure CPAN ( just run CPAN ):

CPAN

After CPAN is configured:

install Authen::OATH [module in CPAN shell, which takes a long time to complete.]

When Authen::OATH is successfully installed, configure 2FA in WebMin.

Permission denied (publickey) fix

$ ls -laZ

$ restorecon -r -vv /home/user/.ssh

How to use multiple SSH key for same user by adding to ssh agent

Generate you ssh public key 

cd ~/.ssh && ssh-keygen

eval $(ssh-agent -s)

ssh-add ~/.ssh/id_rsa