Ref : https://www.malekal.com/fail2ban-comment-debannir-une-adresse-ip/

# afficher les 20 derniers blocages...
tail -20 /var/log/fail2ban.log
 
# afficher les adresses IP bannies...
fail2ban-client get sshd banip
 
# débannir  l'adresse IP 
fail2ban-client set sshd unbanip IP