Fail2Ban how to and tips

Fail2Ban, setup, tweaks, possible issues, log and information :

Information :

Fail2Ban max ban time.

Log :

Where is Fail2Ban log.

Setup :

Setup Fail2Ban.

Tweaks :

Add shrunk window jail to Fail2Ban.
Definitely ban an IP in your server via SSH.

Issues :

Fail2Ban doesn’t work.
Fail2ban : ERROR No ‘host’ group in ‘kernel.
Shrunk-window.conf doesn’t work.