Any system authorized by user and password is possible hacked by password dictionary hacking. So we need to define some rule to identify who is hacking your system and who is not. We usually use retry times to identify this. When a user entered wrong password for 'N' times. System will do some action (by blocking IP address or disabled the user for a few hours) to prevent password retry many times. And here is a nice software to provide this service.

### fail2ban
Fail2ban is a software that will parse (most common) application log files. When continuous error found. Fail2ban will setup a rule on firewall to block the access from target IP address. Aim to protect your system from unauthorized access.

### Install
You may run the following commands to install fail2ban to your system.
```sh
$ sudo apt-get update
$ sudo apt-get install fail2ban -y
$ sudo service fail2ban start
```
For more information please visit : 
[fail2ban official site](https://www.fail2ban.org/wiki/index.php/Fail2Ban)