Unable to install fail2ban on Ubuntu 16.04 LTS server!

Question

I installed a new Ubuntu 16.04 LTS server. I want to protect it with fail2ban, but when I try to install the package I get an error.

How do I resolve this problem?

> apt-get install fail2ban
Lecture des listes de paquets... Fait
Construction de l'arbre des dépendances       
Lecture des informations d'état... Fait
fail2ban is already the newest version (0.9.3-1).
0 mis à jour, 0 nouvellement installés, 0 à enlever et 0 non mis à jour.
1 partiellement installés ou enlevés.
Après cette opération, 0 o d'espace disque supplémentaires seront utilisés.
Souhaitez-vous continuer ? [O/n] o
Paramétrage de fail2ban (0.9.3-1) ...
Job for fail2ban.service failed because the control process exited with error code. See "systemctl status fail2ban.service" and "journalctl -xe" for details.
invoke-rc.d: initscript fail2ban, action "start" failed.
dpkg: erreur de traitement du paquet fail2ban (--configure) :
 le sous-processus script post-installation installé a retourné une erreur de sortie d'état 1
Des erreurs ont été rencontrées pendant l'exécution :
 fail2ban
E: Sub-process /usr/bin/dpkg returned an error code (1)

> systemctl status fail2ban.service
 fail2ban.service - Fail2Ban Service
   Loaded: loaded (/lib/systemd/system/fail2ban.service; enabled; vendor preset: enabled)
   Active: inactive (dead) (Result: exit-code) since mar. 2016-11-15 16:02:23 CET; 2min 43s ago
     Docs: man:fail2ban(1)
  Process: 11301 ExecStart=/usr/bin/fail2ban-client -x start (code=exited, status=255)

nov. 15 16:02:23 MBjumpbox systemd[1]: fail2ban.service: Control process exited, code=exited status=255
nov. 15 16:02:23 MBjumpbox systemd[1]: Failed to start Fail2Ban Service.
nov. 15 16:02:23 MBjumpbox systemd[1]: fail2ban.service: Unit entered failed state.
nov. 15 16:02:23 MBjumpbox systemd[1]: fail2ban.service: Failed with result 'exit-code'.
nov. 15 16:02:23 MBjumpbox systemd[1]: fail2ban.service: Service hold-off time over, scheduling restart.
nov. 15 16:02:23 MBjumpbox systemd[1]: Stopped Fail2Ban Service.
nov. 15 16:02:23 MBjumpbox systemd[1]: fail2ban.service: Start request repeated too quickly.
nov. 15 16:02:23 MBjumpbox systemd[1]: Failed to start Fail2Ban Service.

/var/log/fail2ban.log is empty:

ls -l /var/log/fail2ban.log
-rw-r----- 1 root adm 0 nov.  15 16:02 /var/log/fail2ban.log

Answer 1

OK finally I resolve it with :

• apt-get remove fail2ban
• apt-get autoremove
• apt-get install fail2ban

Answer 2

Resolved by the following.

apt-get remove fail2ban
apt-get autoremove
rm -rf /etc/fail2ban/
apt-get install fail2ban

Answer 3

The user editable file is jail.local. Jail.conf on the 16.04 version needs to be copied to a new jail.local file. You then manually "diff" the old .local and the new .local file and copy any changes in manually. This fixed the problem for me!