How to resize and extend centos 7 disk manually

How to secure your SSH.

 
1. Permanently stop and disable ssh services (ubuntu)

command: sudo systemctl stop ssh

                sudo systemctl disable ssh

                sudo systemctl status ssh

To check if ports 22 still open after disable ssh

command : sudo lsof -i:22

* Please run this command from server terminal in nutanix web

reference -: https://www.cyberciti.biz/faq/howto-start-stop-ssh-server/ 

2. Reject all IP & accept ssh connection only by allow IP Address

reference-: https://docs.rackspace.com/support/how-to/restrict-ssh-login-to-a-specific-ip-or-host/

3. Using knockd filter ssh connection by knock port

reference-: https://www.linuxbabe.com/security/secure-ssh-service-port-knocking-debian-ubuntu

4. Using passwordless SSH login

reference-: https://www.linuxbabe.com/linux-server/setup-passwordless-ssh-login