我跑：
sudo apt-get update
sudo apt-get install fail2ban
sudo cp /etc/fail2ban/jail.conf /etc/fail2ban/jail.local
无需激活任何监狱或其他任何东西：
sudo systemctl restart fail2ban
Job for fail2ban.service failed because the control process exited with
error code. See "systemctl status fail2ban.service" and "journalctl -xe" for
details.
sudo service fail2ban status
● fail2ban.service - Fail2Ban Service
Loaded: loaded (/lib/systemd/system/fail2ban.service; enabled; vendor
preset: enabled)
Active: inactive (dead) (Result: exit-code) since Mon 2018-01-01 15:04:10
UTC; 24s ago
Docs: man:fail2ban(1)
Process: 9828 ExecStop=/usr/bin/fail2ban-client stop (code=exited,
status=0/SUCCESS)
Process: 14906 ExecStart=/usr/bin/fail2ban-client -x start (code=exited,
status=255)
Main PID: 647 (code=killed, signal=TERM)
Jan 01 15:04:10 benja2 systemd[1]: fail2ban.service: Control process exited,
code=exited status=255
Jan 01 15:04:10 benja2 systemd[1]: Failed to start Fail2Ban Service.
Jan 01 15:04:10 benja2 systemd[1]: fail2ban.service: Unit entered failed
state.
Jan 01 15:04:10 benja2 systemd[1]: fail2ban.service: Failed with result
'exit-code'.
Jan 01 15:04:10 benja2 systemd[1]: fail2ban.service: Service hold-off time
over, scheduling restart.
Jan 01 15:04:10 benja2 systemd[1]: Stopped Fail2Ban Service.
Jan 01 15:04:10 benja2 systemd[1]: fail2ban.service: Start request repeated
too quickly.
Jan 01 15:04:10 benja2 systemd[1]: Failed to start Fail2Ban Service.
我该如何设置 fail2ban 以便它能够启动？