Failed to initialize any backend for Jail sshd

Nach der Installation von fail2ban zeigt systemctl status fail2ban folgendes an:

# systemctl status fail2ban

× fail2ban.service - Fail2Ban Service
     Loaded: loaded (/lib/systemd/system/fail2ban.service; enabled; preset: enabled)
     Active: failed (Result: exit-code) since Fri 2024-05-03 10:30:22 CEST; 54s ago
   Duration: 163ms
       Docs: man:fail2ban(1)
    Process: 4115 ExecStart=/usr/bin/fail2ban-server -xf start (code=exited, status=255/EXCEPTION)
   Main PID: 4115 (code=exited, status=255/EXCEPTION)
        CPU: 142ms

Mai 03 10:30:22 backup systemd[1]: Started fail2ban.service - Fail2Ban Service.
Mai 03 10:30:22 backup fail2ban-server[4115]: 2024-05-03 10:30:22,685 fail2ban.configreader   [4115]: WARNING 'allowipv6' not defined in 'Definition'. Using default one: 'auto'
Mai 03 10:30:22 backup fail2ban-server[4115]: 2024-05-03 10:30:22,698 fail2ban                [4115]: ERROR   Failed during configuration: Have not found any log file for sshd jail
Mai 03 10:30:22 backup fail2ban-server[4115]: 2024-05-03 10:30:22,702 fail2ban                [4115]: ERROR   Async configuration of server failed
Mai 03 10:30:22 backup systemd[1]: fail2ban.service: Main process exited, code=exited, status=255/EXCEPTION
Mai 03 10:30:22 backup systemd[1]: fail2ban.service: Failed with result 'exit-code'.

Lösung:
1. erstelle die Datei jail.local unter /etc/fail2ban/jail.local und trage folgendes ein:

# nano /etc/fail2ban/jail.local

[sshd]
enabled = true
backend = systemd

2. installiere das Paket python3-systemd:

# apt install python3-systemd

3. starte fail2ban neu:

# systemctl restart fail2ban