Sudo is a program that allows users to run programs with the security privileges of another user (normally the superuser, or root). The /etc/sudoers file controls who can run what commands as what users on what machines and can also control special things such as whether you need a password for particular commands. To add…

Fail2ban is an important software for system administrator. It scans log files (e.g. /var/log/auth.log) and bans IPs that show malicious signs, something like too many password failures and looking for exploits. To install fail2ban, execute this command: Open the configuration file to activate some rules: Find following line to set email destination for notification: Find…